5 Misconceptions About Robotic Welding Guns and Consumables

Robotic MIG welding guns and consumables are an important part of the welding operation yet are frequently overlooked when investing in robotic welding systems. Companies may often choose the least expensive option when, in reality, purchasing quality robotic MIG guns and consumables can lead to significant cost savings in the long run. There are many other common misconceptions about robotic MIG guns and consumables that, if corrected, can help increase productivity and decrease downtime for the entire welding operation.

Here are five common misconceptions about MIG guns and consumables that may be affecting your robotic weld cell.  

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Reduce Downtime and Costs with Water-Cooled Robotic MIG Guns

For many fabricators, the choice between an air-cooled and water-cooled robotic MIG welding gun is easy. Their heavy-duty applications simply demand a water-cooled model due to the high amperage and duty cycle requirements of the job — an air-cooled gun would overheat and fail prematurely under such conditions.

In the right application, a water-cooled robotic MIG gun can often prove beneficial by minimizing downtime, increasing productivity and reducing consumable costs. These guns typically have higher duty cycles than air-cooled models and operate at higher amperages, which means they can run for longer periods of time.

Still, deciding whether an operation would benefit from converting to a water-cooled MIG gun involves a careful analysis of several factors. In addition to considering the amperage requirements and duty cycle, a fabricator should consider the upfront costs, potential return on investment (ROI) and the specific application.

For example, some fabricators may choose a water-cooled robotic MIG gun because of the length of their welds — they need a long arc-on time to produce long welds, which generates more heat in the gun. Similarly, critical start-and-stop points along a longer weld joint typically require a gun that can handle extended weld times.

The weld joint design and type or thickness of the material can also help determine whether to switch to a water-cooled MIG gun. For instance, heavy plate sections that have been preheated can generate substantial radiant heat that impacts how well a gun cools, and can adversely affect the life of the front-end consumables. In this scenario, a water-cooled gun would be better suited for the job.

When deciding whether a water-cooled robotic MIG gun is the best choice for an application, it’s important to keep in mind some maintenance and replacement costs. While a water-cooled gun costs more upfront, there is the possibility to conduct maintenance on each individual component within the cable assembly (e.g. water lines, gas hose, etc). However, an air-cooled cable combines all its components into one common part and if any single component fails, the entire cable needs to be replaced, resulting in higher replacement costs. It is necessary to weigh those factors against each other.

Understanding water-cooled robotic MIG guns

Welding guns — whether air or water-cooled — must stay cool to protect the power cable, gun body, neck and consumables from heat damage during welding. That heat takes three forms: radiant heat from the arc; resistive heat from the electrical components in the welding circuit; and reflective heat from the welded part, particularly aluminum or preheated parts.

Whereas an air-cooled MIG gun relies on the ambient air, shielding gas and arc-off time to dissipate heat, a traditional water-cooled robotic MIG gun circulates a coolant from a radiator unit through cooling hoses inside the power cable and into the gun body and neck. The coolant then returns to the radiator, where the radiator’s baffling system releases the heat absorbed by the coolant. There are also guns available on the market today that cool only the front of the gun, where heat is generated, and still use an air-cooled cable.

Air-cooled MIG guns also use much thicker copper cables and inner neck tubes, whereas water-cooled robotic MIG guns use much less copper in the power cables and thinner wall sections in the necks because the coolant carries away the resistive heat before it builds. Water-cooled MIG guns, however, do have multiple inner lines that run through the neck to the front-end consumables, making this portion of the gun heavier than an air-cooled neck.

When to switch to a water-cooled robotic MIG gun

There are three key indicators that signify a welding operation could benefit from converting to a water-cooled MIG gun:

1. Excessive consumable usage
2. Excessive gun temperature (overheating)
3. Excessive cycle time (high duty cycle)

All these factors are interconnected, because if the weld is too hot, excessive consumable usage and gun temperature will automatically result.

In general, water-cooled robotic MIG guns are most beneficial for high-amperage applications and are typically available in 350 to 600 amp models.

Closely related to amperage is duty cycle, which refers to the amount of time during a 10-minute cycle that the gun can operate at its rated capacity without overheating. Water-cooled robotic MIG guns have varying duty cycle capacities depending on the manufacturer and model. It is important to make the appropriate comparison during the selection process, as some guns may be rated at either 60% or 100% duty cycle, which results in different amperage ratings. 

Converting to a water-cooled robotic MIG gun

Fabricators who plan to change from an air-cooled to a water-cooled robotic MIG gun should follow these three steps to help ensure a smooth conversion.

Match the existing tool center point (TCP) and approach angle. Be sure to have access to all the weld joints with the new water-cooled MIG gun. Make sure that the tooling will work with the new system. The gun may require a special neck or special mounting arm to achieve the desired TCP. Often, converting to a water-cooled gun will require a new mounting arm and insulating disk to maintain or achieve a specific TCP while changing the dimensions of the neck itself to create better access.

Ensure overall clearance. A 3-D simulator can help determine whether all parts of the new system will clear all tooling or any other obstructions. In addition to having front-end clearance and access – once installed, it’s important that the gun body and cable bundle fits properly to avoid getting caught on tooling or other equipment. 

Get a water cooler. It is necessary to invest in a radiator for the new water-cooled robotic MIG gun. Ensure that the water-cooler has been installed and maintained, as per the manufacturer’s specifications.

Maintenance and usage tips

Because all the lines and hoses in a water-cooled robotic MIG gun are separate, it is possible to conduct maintenance on individual components if they become damaged. However, due to the lines being internal to the gun, it is difficult to perform preventive maintenance on them. There are options though to care for a water-cooled gun.

As with an air-cooled MIG gun, it’s important to inspect a water-cooled robotic MIG gun to ensure that all consumables and connections are tight and working properly. Inspect the water lines frequently to make sure they are tight and have no leaks, and replace the O-rings when necessary (e.g. when cracks or wear appears). Ensure there is a flow switch installed in the return line from the gun and the radiator to indicate any leaks within the system — this component will save time and money in the event of a failure.

Using a reamer or nozzle cleaning station adds significant benefits to the preventive maintenance of water-cooled robotic MIG guns. A reamer eliminates the need to manually clean out the front-end consumables and can, with the addition of an automated sprayer, add anti-spatter compound to help further extend consumable life. This feature adds to the overall cost of the equipment, but it helps increase uptime for production since there is less manual intervention. The ROI is typically worth it.

It is important to always use the correct coolant — do not fall prey to the notion that it is cheaper to use tap water in a water-cooled gun. Doing so can cause algae growth or mineral build-up and, eventually, lead to costly clogging. Instead, use deionized water or the specially treated coolant solution recommended by the manufacturer. These coolants contain special additives to lubricate internal pumps and O-rings, as well as to prevent algae growth. 

Lower operating costs

Although converting to a water-cooled robotic MIG gun is often more of a necessity than a choice (because the application demands it), this type of gun has its value. Applying a water-cooled gun to the appropriate application can result in a more efficient system performance and lower overall operating costs.

Consider the various costs, specific application needs and joint accessibility to determine whether a water-cooled robotic MIG gun is the best option for the specific robotic application — and don’t hesitate to consult a trusted welding distributor, welding equipment manufacturer or robotic welding system integrator with questions. 

Maintaining TCP: How Does Your Robotic MIG Gun Neck Factor In?

A robotic MIG welding system contains many components that impact the quality of the parts it welds, its productivity and the overall operational costs. Among those, the robotic MIG gun neck plays a larger role than may first be apparent. Why? The durability of the gun neck — and especially its ability to withstand impacts — is important for maintaining tool center point (TCP).

The value of TCP

An accurate TCP provides consistency and repeatability from part to part, and is key to the system’s ability to maintain weld positions, especially in assembly line welding where new parts are continually entering the weld cell.

A productive and efficient robotic welding system places welds in the same place every time. To achieve this, the MIG gun neck needs to stay in its expected position. A weak neck that easily bends during routine welding can lead to TCP problems over time, as can rough handling of the neck during consumable changeover.

Issues with TCP can lead to additional spatter or missed welds, causing rework or scrapped parts. These cost time and money in lost productivity and in wasted parts. An inaccurate TCP can also cause the neck to crash into parts or tooling, potentially leading to damage and unplanned downtime.

When selecting a robotic MIG gun neck, look for durable, high quality materials and robust construction. The goal is to have a neck that is strong enough to withstand minor crashes without bending.

In addition, be certain there is a solid connection from the neck to the gun, and from the gun to the mounting arm in a conventional system or to the robot itself in a through-arm system. Any play in the system can negatively impact TCP.

Air-cooled or water-cooled gun?

Neck durability varies, depending on if the application uses an air-cooled or a water-cooled robotic MIG gun.

Some applications require water-cooled guns to protect the gun and the neck in high-temperature continuous welding; however, these guns tend to be less durable in a crash than air-cooled gun necks due to the internal soldering of copper and brass lines for the water passages.

Air-cooled guns typically feature copper tubes covered with insulation and aluminum, making them stronger and more able to resist an impact.

Some manufacturers offer a hybrid air/water-cooled robotic MIG gun, in which the water lines run external to the neck. This type of gun tends to have a stronger neck, like an air-cooled gun, which makes it more tolerant to crashes. However, it is important to ensure the water lines do not hit tooling or parts, which can negatively affect TCP or create leaks.

Getting the best performance

Some key best practices can help protect the neck and provide consistent TCP:

Collision Detection

All robotic welding systems require a form of collision detection to prevent damage to both the robotic MIG gun and the robot arm in the event of an impact. Some robotic systems incorporate robot collision detection software. Systems that do not have built-in collision detection should always be paired with a clutch — an electronic component that attaches to the gun to protect it and the robot from heavy damage in the event of a collision.

Neck Inspection Fixture

Another key peripheral is a neck inspection fixture, which verifies that the gun’s neck is set to the intended TCP and allows the neck to be readjusted after a collision or if it becomes bent during routine welding. If neck adjustment is needed, the welding operator simply adjusts the neck to meet the proper specifications. This prevents costly rework due to missed weld joints and can reduce downtime to reprogram the robot to meet the welding specifications with a bent neck.

Spare Necks

Having spare necks ready helps gets the system back online quickly. The welding operator need only remove the bent neck in the event of a crash and exchange it with a spare one. The damaged neck can be set aside for inspection later, minimizing interruption to the weld cycle.

Reamer Quality

Choose a high-quality reamer to avoid potential damage to the gun or neck. A reamer, or nozzle cleaning station, removes spatter from the nozzle and clears away the debris that accumulates in the diffuser during welding. A high-quality reamer securely holds the gun in place during the ream cycle, which reduces the risk of bending the neck and compromising TCP.

5. Proper neck and consumable installation and ongoing maintenance are important. Make sure to tighten these components to factory specifications. When changing consumables, remove them with the right tools to avoid bending the gun neck.

Optimize the system to ensure proper TCP

In many cases, a robotic welding system can provide a competitive edge — offering greater productivity, quality and cost savings. Take care to protect the MIG gun neck, and follow best practices for setup and maintenance, to help ensure the system maintains optimal TCP and the operation experiences minimal downtime.  

What to Know About Liners for Robotic Welding Guns

The liners used in a robotic gas metal arc welding (GMAW) gun play a significant role in the productivity, cost and quality in your automated welding operation, alongside other consumables such as the nozzle, retaining head (or gas diffuser) and contact tip. Liners run the length of the robotic welding gun and power cable — from the contact tip to the power pin — and act as the conduit through which the wire is fed.

A poorly installed liner can lead to problems with bird-nesting and excessive debris in the liner, which can both cause wire feeding issues that lead to downtime — the enemy of any robotic welding operation.

For this reason, it is imperative to select the right liner for the wire type and diameter being used and to trim it to the proper length.

This article has been published as a web-exclusive on thefabricator.com. To read the entire story, please click here. 
 

Choose the Right Power Cable to Reduce Downtime in Robotic Welding Applications

In robotic MIG welding applications, minimizing downtime is key. It reduces costs and improves efficiencies to help an operation meet its production goals. Gaining the best performance, in part, depends on the equipment being used. Having the right robotic MIG gun and power cable, for example, is critical. 

There are several factors to consider when determining the right gun style and cable length for the application. Prioritizing these are important, as using the wrong length cable can cause problems ranging from premature cable failure to poor wire feeding.  

Conventional vs. through-arm guns 

Before selecting the power cable length, first consider whether a conventional gun or a through-arm robotic gun is best-suited for the application. Each style has its advantages and limitations.

Through-arm robotic welding systems have become more common, as more equipment manufacturers develop this style compared to conventional robots. Through-arm robotic welding systems, however, allow for the mounting of either a through-arm gun or a conventional one. In some applications, the latter is the better choice. 

When choosing between the two, consider the available space and weld cell layout, joint access and the type of material being welded. 

Conventional guns can often access joints better and/or maneuver around tooling or fixturing that a through-arm gun can’t reach. Conventional guns can also be less expensive and faster to install, although they do require proper cable management. They also require more space, so they aren’t typically the best choice in smaller weld cells. 

Through-arm guns work well in applications where deep access to the part or fixture is necessary. Since they don’t have a mounting arm and take up less space, they also offer advantages in smaller weld cells. The design of the gun —with the power cable assembly running through the arm of the robot —manages excess cable slack, which typically helps them last longer than a conventional power cable.  

Choosing the right cable length 

Selecting the proper cable length is critical for both types of guns and numerous factors impact the choice. These include wire feeder, the make and model of the robot, and robot articulation. 

Having the right cable length helps prevent problems with wire feeding that can lead to downtime and unnecessary labor and/or part costs to address the issue. The wrong cable can further increase costs and downtime due to premature cable failure.   

When using a conventional gun, a cable that is too short causes tension, which can result in components prematurely breaking down in the cable assembly. It can also cause the clutch or the robot to overload, which will send a collision detection signal that stops the robot — resulting in unnecessary downtime. A cable that is too long is also a problem, because it can get caught on tooling or result in extra weight that bogs down the mounting arm – potentially overloading the clutch. 

With a through-arm gun, a too-short cable with visible tension also causes problems. Choose a cable that allows some slack for the robot arm to move around. But remember, too much slack can be as problematic as too little slack. 

When choosing proper cable length for a through-arm gun, it’s important to know the robot make and model, the feeder make and model, and the measurements of the system. If any nonstandard equipment or tooling is mounted to the face of the robot, such as a gripper or a camera, this changes the thickness of the plate and therefore impacts the necessary cable length, requiring it to be longer. It is also important to know where the wire feeder is mounted relative to the robot casting to ensure proper cable length.

Much of the same information is needed in choosing the right cable length for a conventional gun: robot make and model, feeder make and model. In addition, consider where the feeder is mounted on the robot or even remotely, as both will affect cable length. 

For both types of guns, the feeder should be adjusted each time the cable is replaced to manage cable slack properly. Failing to properly adjust the wire feeder can result in a cable that is too tight or long for the given application, causing premature failure and potential damage to the robot or wire feeder.

Fixing these issues at the start of the process can help avoid much greater downtime and costs later. 

Key best practices

Following some best practices can help extend power cable life, reduce downtime and improve productivity. Many of the best practices are related to the programming of the automated welding system. 

Oftentimes, cables fail because they were set up to fail — the system is asking too much of the cable. Make sure the robot doesn’t articulate too far in either direction, to avoid placing excess stress on the cable, whether it is a conventional or through-arm robotic gun. 

It’s also important to limit the movements of axis five (bending) and axis six (rotation) to help extend cable life. The joints of the robot get smaller as they move from the base to the wrist. Use the larger joints nearer to the base as much as possible and rely on the smaller joints only when necessary to reach the weldment. 

In addition, employ a cable management system when using a conventional gun to ensure there isn’t too much slack in the cable. With too much slack, the cable will rub on anything around it and possibly catch on fixturing. When a robot moves at production speed, it can break the cable or fixture. Cable management systems can take the form of a recoil with an adjustment knob and pulley that allows the maintenance personnel or welding operator to adjust the position (length) and tension of the power cable.   

When using a through-arm gun, choose a rotating power cable connection to reduce the stress on the system. Conventional style unicables typically come with a crimped or solid connection, which limits rotational capabilities and produces torsional stress on the cable. Unlike conventional unicables, a power cable that incorporates a rotating power connection allows for stress-free rotation — and can ensure a longer cable life. 

Reduce downtime with the right choice

Without the right equipment — and proper system programming — downtime can cost significant time and money in robotic welding applications. Take care upfront to choose the right equipment, including the gun and power cable, to save time and money in the long run and keep the operation running smoothly. 

Conventional Guns on Through-Arm Robotic Welding Systems: When to Make the Choice

Through-arm robotic welding systems are becoming increasingly common in the industry, as more equipment manufacturers turn to the development of this style compared to conventional robots. However, there are some applications where it is better to use a conventional robotic gun for these systems, instead of the through-arm gun typically chosen.

The good news is that most through-arm robotic welding systems allow for mounting either type of gun — providing more options and flexibility depending upon the needs of the application. And while the choice of gun is sometimes an afterthought, it can significantly impact efficiency, throughput and quality of the finished weld. Choosing the best option for the job up front is key. 

Considerations in choosing robotic guns

As the name suggests, the power cable assembly of a through-arm MIG gun runs through the arm of the robot as opposed to over the top of it like in a conventional gun. Because of this design, the through-arm gun style is often more durable, since the power cable is protected.  However, because conventional guns can be used on either type of system — a through-arm robotic system or a conventional robot — they can sometimes offer greater flexibility, and can be used with more robot makes and models. 

There are numerous factors to consider when making the choice between a through-arm gun and a conventional robotic gun for a through-arm robotic welding system:

• Available space and weld cell layout
• Reach and access to weldment
• Type of material being welded 

Benefits of conventional guns

Conventional style guns, which typically offer a longer neck, can provide more flexibility in accessing or reaching certain weldments, whereas through-arm guns may have difficulty reaching around fixturing or tooling in some cases. In applications where a through-arm gun is installed and it doesn’t reach the weldment as needed, a conventional gun can be swapped in for access purposes.

In addition, conventional guns are often a good choice in smaller, more modular weld cells that feature short-armed robots. Through-arm guns may not work as well in these situations because there is not as much cable, and therefore the robot doesn’t have as much slack for articulation.

Also, because of the way the cable lies in a conventional gun, the bend radiuses of the cable are much larger than in through-arm guns. When welding aluminum, for example, wire feeding is a major contributing factor to poor weld quality, and therefore tight bend radiuses are not recommended. This makes conventional guns a good option when robotic welding aluminum.

Uptime and throughput are also critical in robotic welding applications, and maintenance is a key factor that impacts productivity, downtime and costs. Conventional guns often provide easier maintenance because everything is outside of the arm, allowing for parts to be changed or repaired quickly to minimize downtime. Another benefit of conventional guns is they tend to be more cost-effective to purchase and can be installed much faster — saving time and money in setup. 

When to stay with a through-arm gun

Through-arm guns provide their own advantages when matched with a through-arm robotic welding system. In applications that require plunging deeply into a fixture or part, a through-arm gun is often a better choice. Think of a through-arm gun as an extension of the robot arm. This extension allows it to access different areas within the part being welded, depending on the application.

In addition, because the cables are more protected on a through-arm gun they tend to last longer overall, which helps reduce replacement costs. The through-arm design naturally protects the power cable and makes it less prone to snagging on fixturing, rubbing against the robot or wearing out from routine torsion.  

Best practices for performance

With either a conventional gun or a through-arm gun, there are some common best practices that can contribute to success in robotic MIG welding.

First, it is critical that the cable is never under tension when using a through-arm gun, to help prevent premature cable failure. Cable tension is visible on a conventional style gun but not on a through-arm gun since the cable runs through the gun. This makes proper setup especially important with through-arm guns.

In addition, it’s best to use a cable management system when using a conventional gun to ensure there isn’t too much slack in the cable. With too much slack, the cable will rub on anything around it and possibly catch on fixturing. When a robot moves at production speed, it can break the cable or fixture. Keep these factors in mind, along with joint access requirements and weld cell layout, when making the gun choice to help improve throughput and productivity. 

Six Tips for Implementing Your Robotic GMAW Gun … and Getting the Most From It

As companies seek to gain a competitive edge, it’s not surprising that some turn to welding automation. It offers numerous advantages, including greater productivity, improved quality and cost savings compared to a semi-automatic welding operation. However, to gain the most out of the investment it’s important to follow some best practices in the weld cell. These considerations include the careful selection, installation and maintenance of gas metal arc welding (GMAW) guns.

As with any type of welding equipment, the goal is to implement the GMAW gun in a manner that optimizes performance, reduces downtime and prevents the accrual of unnecessary costs. It is important to note that the considerations for achieving these benefits may vary depending on whether the robotic welding system uses a through-arm gun or a conventional-style gun. Following are some tips to help.  

Tip No. 1: Choose a solid mount instead of a clutch

All automated welding systems need some form of collision detection to minimize damage to the robot and the GMAW gun in the event of an impact. Today’s robots typically have built-in collision detection software, making it appropriate to use only a solid gun mount to connect and position the GMAW gun. In some cases, companies like the secondary insurance of using a clutch on robots featuring this software. Doing so, however, can add unnecessarily to the expense of the operation, increase weight on the front end of the robot arm and cause the tool center point (TCP) to be less repeatable. When possible, it is preferable to use a solid mount coupled with collision detection built into the robot, instead of a clutch.

Solid mounts offer numerous advantages, especially for systems using a through-arm style gun. A solid mount can aid in achieving a more accurate TCP, providing greater repeatability for more consistent welds. They are also more cost effective and lighter weight, which allows for quicker movement and potentially better productivity. The use of a solid mount, in conjunction with a through-arm robotic GMAW gun, typically opens up the work envelope, so the robot arm can better access the weld joint.

For systems with a conventional gun, a solid mount provides little benefit over a clutch in terms of opening up the work envelope or increasing productivity due to the position of the gun in comparison to the faceplate of the robot. 

Tip No. 2: Use an air blast feature

Air blast is an optional technology on GMAW guns that can help enhance gun performance. This feature can be factory-installed or retrofitted into a gun. Utilizing air blast when possible helps eliminate debris in the front part of the robotic GMAW gun, reducing opportunities for weld contamination that can lead to poor weld quality, costly rework and downtime.

As the name implies, the air blast feature blows compressed air through the front of the gun to remove debris. It can be used with air-cooled robotic guns or water-cooled models.

In addition to removing debris that can cause poor weld quality or contamination, air blast can help increase the time between cycles by removing spatter from the front of the gun. The air blast function can also be used to cool down the gun between weld passes, to help operations avoid going over the duty cycle limit when using air-cooled guns. 

Tip No. 3: Utilize a simulation program

Using simulation software to model the proposed weld cycle before selecting and implementing a robotic GMAW gun can help in achieving the best results with an automated welding system. While the goal with an automated welding system is often to move as quickly and freely as possible, it’s important to remember that it’s typically best to limit excessive robot movements, as it results in longer gun life thanks to reduced equipment stress. Simulation programs can be used to determine proper system setup, including TCP requirements and which nozzle and GMAW gun neck are best suited to get the desired joint access or angle.

The reach and access of the gun neck, in particular, is an important factor in system movement and stress. Changing the neck angle from 22 degrees to 45 degrees, for example, can have a significant impact on robot articulation.

This is where a simulation program is beneficial, since it can be used to determine the type of neck and the neck angle that are best for the application before making the investment. To gain optimum speed and performance from the gun, it may be as simple as slightly adjusting the height of the risers or tooling to gain better access to the weld and reduce stress on the gun. 

Tip No. 4: Utilize a neck inspection fixture

Among several peripherals that can be added to maximize system performance, a neck inspection fixture is one that can help improve throughput, minimize unnecessary downtime — and help gain the best performance from the robotic GMAW gun. A neck inspection fixture verifies that the gun neck is set to the intended TCP and allows the neck to be readjusted after a collision or if it becomes bent during routine welding.

When neck adjustment is needed, the welding operator can simply adjust the neck to meet specifications. This helps prevent costly rework due to missed weld joints and can prevent the downtime it takes to reprogram the robot to meet the necessary welding specifications with a bent neck on the gun.

In some cases, the welding operator can simply remove the bent neck and exchange it with a spare neck to get the system back online quickly. The damaged neck can be set aside for inspection later, resulting in less interruption to the weld cycle.

Using a neck inspection fixture from day one of an automated welding system helps ensure a consistent TCP.

Tip No. 5: Ensure proper gun and cable installation

Choosing the right gun and cable for the application — and installing them properly — are key steps toward maximizing performance of the robotic GMAW gun. Consider the weld length, the required amperage and the type and thickness of material being welded when selecting a robotic GMAW gun.

Air-cooled guns work well on lower amperage applications and high-volume welds. In heavy equipment manufacturing and similar industries, a water-cooled GMAW gun may be necessary to weld on thicker materials for longer periods of time. Water-cooled guns offer high amperages — usually up to 600 amps — at 100 percent duty cycle.

Selecting the appropriate neck, power cable and other gun components can also have an impact on productivity and performance. Choosing the proper neck style and length for the application provides the gun with easy and complete access to the weld joint, which helps reduce weld defects and downtime for rework. Available neck angles typically range from 180 to 45 degrees, with varying lengths to accommodate most robotic welding applications. Necks can also be special ordered for custom TCP requirements when necessary.

Tip No. 6: Conduct proper gun maintenance

In addition, power cable style and length can also impact efficiency in robotic welding operations. For through-arm applications, the power cable is often sold in set lengths to match a specific model of robot, so the selection process is easier. For conventional style robots, it’s important to verify the exact length needed. Too long of a cable can easily kink or move during the welding process, while too short of a cable can stretch and shorten cable life. In both cases, it can result in downtime, premature cable failure and increased costs.

Also, look for a sturdy power cable that can withstand UV damage from the arc and resist wear. Cables with quick-change features can extend cable life, simplify cable changeover and maximize arc-on time when installed properly.

Choosing and properly installing the right gun and cable is just the beginning. Proper ongoing maintenance is also an important factor to optimize performance.

Regularly check all connections on the GMAW gun to ensure they are tight and secure. Doing so helps prevent issues that can lead to weld defect and downtime. Tighten front-end consumables and check that all seals are in good condition. Also be certain the power pin is secure. While checking that welding cable leads are secure, look for signs of wear and replace them as necessary.

Remove spatter from the GMAW gun nozzle regularly, ideally applying anti-spatter to protect against buildup. Implement a reamer when possible to minimize damage to the gun and front-end consumables. A reamer (or nozzle cleaning station) removes spatter from the nozzle bore and clears away debris that accumulates around the diffuser during welding, resulting in longer life of the consumables and higher weld quality. The reamer can be programmed to run between welding cycles — either during part loading or transfer — so it does not add to the overall cycle time per part.

In addition, track the life span of the GMAW gun liner and replace it prior to failure. Replacement liners should be trimmed to the appropriate length using a liner gauge.

Automated welding operations that are larger in size may need to do more frequent preventive maintenance. It’s especially important for companies that complete large weldments on thick materials because they stand to have greater costs and downtime for rework in the event of gun failure. 

Optimize the system

Automated welding systems add speed, accuracy and repeatability to the welding operation. They can help companies increase productivity and reduce costs in a relatively short period.

Implementing some best practices can help companies extend the life of the GMAW gun and consumables, and optimize performance and efficiency of an automated welding system — offering them the most out of the investment. 

Through-Arm Robotic MIG Guns: Top 10 Things to Consider 

In recent years, the industry has seen advancements in robotic welding technologies that help companies improve productivity and quality and gain a competitive edge. The transition from conventional robots to through-arm robots is among those advancements. 

These robots require the use of through-arm robotic MIG guns. As the name suggests, the cable assembly of a through-arm MIG gun runs through the arm of the robot, improving its overall durability. The through-arm design naturally protects the power cable and makes it less prone to snag on fixturing, rub against the robot or wear out from routine torsion — all of which can lead to premature cable failure.  

Since through-arm robotic MIG guns don’t require a mounting arm like conventional robotic MIG guns do, they provide a smaller work envelope. This makes them particularly advantageous when working in tight spaces. 

Here are the top 10 things to consider when selecting, installing and maintaining a through-arm robotic MIG gun: 

1) Look for a gun that offers good power cable rotation.

When choosing a through-arm robotic MIG gun, look for one that offers good power cable rotation. For example, some manufacturers place a rotating power connection on the front of the cable that allows it to rotate 360 degrees. This ability provides stress relief for the cable and power pin, and allows for greater maneuverability for a wider range of applications. It also helps prevent cable kinking that could lead to poor wire feeding, conductivity issues, or premature wear or failure. 

2) Look for power cables constructed of durable components and materials. 

Choosing a through-arm robotic MIG gun is similar to choosing a conventional robotic MIG gun, except that through-arm guns are sold with predetermined cable lengths. It is still important, however, to choose a gun with power cables that are constructed of durable components and materials to help prevent wear or failure. Always know your robot make and model when placing an order for a new gun to ensure you make the proper selection. 

3) Select the proper amperage of gun.

Always select the proper amperage of gun and be certain it has the appropriate duty cycle for the given application. Duty cycle is the amount of arc-on time within a 10-minute period; a gun with a 60 percent duty cycle, for example, can weld for six minutes within that period without overheating. As a rule, most manufacturers offer guns up to 500 amps, in both air- and water-cooled models.  

4) Identify whether the robot has collision software. 

Check if the robot that the through-arm gun is installed on has collision detection software. If not, identify a clutch that will pair with the gun to help ensure the robot remains safe if it collides with a workpiece or tooling.  

5) Consult the manufacturer’s instructions when installing a through-arm robotic MIG gun. 

For through-arm robotic MIG guns, it is important to note that the power cable needs to be installed in a slightly different manner than a conventional over-the-arm robotic MIG gun. Installing a through-arm robotic MIG gun incorrectly can lead to a host of problems, not the least of which is cable failure. Incorrect installation can also cause weld quality issues, such as porosity, due to poor electrical connections; premature consumable failure caused by poor conductivity and/or burnbacks; and, potentially, failure of the entire robotic MIG gun. To prevent such problems, it is imperative to consult the manufacturer’s instructions for each specific MIG gun. 

6) Be sure the power cable position is correct and avoid making it too taut. 

When installing a through-arm robotic MIG gun, first position the robot with the wrist and top axis at 180 degrees, parallel to each other. Install the insulating disc and spacer the same as with a conventional over-the-arm robotic MIG gun. Be certain that the power cable position is also correct. The cable should have the proper “lie” with the robot’s top axis at 180 degrees. In addition, it’s important to avoid a very taut power cable, as it can cause undue stress on the power pin. It can also cause damage to the cable once the welding current passes through it. For that reason, it’s important to make sure the power cable has approximately 1.5 inches of slack when installing it. (See Figure 1.)

7) Always install the stud into the front housing before bolting the front end onto the robot wrist. 

The stud on the front of the power cable needs to be fully inserted into the front connector of the through-arm robotic MIG gun. To achieve this result, always install the stud into the front housing prior to bolting the front end onto the robot wrist. By pulling the cable through the wrist and making the connections in front of the gun, it’s easy to slide the whole assembly back (once the cable is fastened) and bolt it onto the wrist. This extra step will ensure the cable is seated and will allow for maximum continuity and maximum power cable life.

8) Position the wire feeder close enough to the power cable that it will not be unnecessarily stretched. 

Be certain to position the wire feeder in close enough proximity to the robot that the power cable on the through-arm robotic MIG gun will not be stretched unnecessarily after installation. Having a wire feeder that is too far away for the length of the power cable can cause undue stress on the cable and front-end components.

9) Regularly conduct preventive maintenance and check for clean, secure connections.

Consistent preventive maintenance is key to the longevity of any robotic MIG gun, including the through-arm style. During routine pauses in production, check for clean, secure connections between the MIG gun neck, the diffuser or retaining heads, and the contact tip. Also, check that the nozzle is secure and any seals around it are in good condition. Having tight connections from the neck through the contact tip helps ensure a solid electrical flow throughout the gun and minimizes heat buildup that could cause premature failure, poor arc stability, quality issues and/or rework. In addition, regularly check that the welding cable leads are secured properly and assess the condition of the welding cable on the robotic MIG gun, looking for signs of wear, including small cracks or tears, and replace as necessary.

10) Visually inspect consumables and the gun on a regular basis for signs of spatter.

Spatter buildup can cause excessive heat in the consumables and MIG guns, and block shielding gas flow. Visually inspect consumables and the through-arm robotic MIG gun on a regular basis for signs of spatter. Clean the gun as needed and replace consumables as necessary. Adding a nozzle cleaning station (also called a reamer or spatter cleaner) to the weld cell can also help. Like its name implies, a nozzle cleaning station removes spatter (and other debris) that builds up in the nozzle and diffuser. Using this equipment in conjunction with a sprayer that applies an anti-spatter compound can further protect against spatter accumulation on the consumables and the through-arm robotic MIG gun.

Optimizing the Robotic Welding Process with the Right GMAW Gun

As companies seek out means to increase productivity and improve quality, the investment in welding automation continues to grow across the fabrication and manufacturing industries. Along with providing greater efficiencies, robotic welding systems allow companies to streamline their operations to gain cost savings and to position themselves favorably among the competition. 

Selecting the right robot and power source, and ensuring that the parts to be welded lend themselves to automation — namely that they are repeatable and offer joint accessibility — are all vital to success. There are also steps that companies can take to optimize the robotic welding process by way of the robotic gas metal arc welding (GMAW) gun. From making the proper selection for the application to implementing appropriate preventive maintenance and more, this component can help support greater arc-on time, reduce costs and help companies realize the benefits of welding automation. 

Making the right choice

Determining the right robotic GMAW gun depends on the application, including the type and thickness of material being welded, the length of the weld and the amperage required. The type of robotic welding system also factors into the decision, as through-arm robots are becoming more prevalent in the industry and replacing many conventional robots due to their ability to reduce cable wear from routine torsion. In this case, a through-arm robotic GMAW gun, in which the cable assembly runs through the arm of the robot (as opposed to over it), is necessary. As with conventional GMAW guns, through-arm style guns are available in air- or water-cooled varieties. 

In most applications, air-cooled GMAW guns provide the necessary cooling capacity to protect against premature failure and offer good performance. These guns rely on both the copper in the unicable and the ambient air for cooling. In addition to working well on lower amperage applications, for welding materials up to 0.16-inch thick and for short, high-volume welds, air-cooled GMAW guns are also quite sturdy. 

In heavy equipment manufacturing and similar industries, water-cooled robotic GMAW guns are often chosen due to their ability to weld on thicker materials (over 1/4 inch) for longer periods of time. While more expensive up front and more to maintain, these guns offer high amperages (usually 300 to 600 amps) at 100 percent duty cycle, which makes them well suited for long weldments. These GMAW guns operate by circulating coolant from a radiator unit through the power cable via cooling hoses and through the gun and neck. This coolant returns to the radiator where it releases the heat that it absorbed during the welding process. Because of the water circuit, there is the potential for leaks so companies should take care to implement a preventive maintenance schedule to help protect against issues.  

In the event that a company welds materials of a variety of thicknesses at low and high amperages, a good choice for a GMAW gun is a hybrid variety featuring a durable air-cooled neck with external water lines. 

Choosing proper components 

The neck, power cable and other components chosen for a robotic GMAW gun can have a measurable impact on welding performance and productivity. The goal with each of these items is to keep them functioning correctly and prevent premature failure so that the robot can maintain the high levels of arc-on time it was designed to provide. 

It is important that the robotic GMAW gun is able to access the weld joint accurately and fully, and utilizing the proper neck style and length for the job is key. Typically, GMAW gun manufacturers offer necks in multiple angles ranging from 22 to 180 degrees, and in various lengths to accommodate most robotic welding applications. In some cases, however, it may be necessary to special-order a neck. Whichever the case, having a neck that can reach the weld joint appropriately can reduce weld defects by completing the weld properly the first time, and eliminate downtime for rework. 

The right power cable style and length on a robotic GMAW can also help companies achieve efficiencies in the robotic welding operation. In a through-arm robotic application, the selection is simpler, as the power cable is typically sold in set lengths to match a specific make and model of robot. Still, companies may want to consider additional options for these components, such as power cables with a rotating connection. This feature helps relieve stress on the cable and power pin, resulting in less kinking and a longer life. 

For conventional robots, selecting the correct length of power cable is important — too long of a cable can easily kink or whip around during the welding process, whereas too short of a cable can stretch and wear more quickly. Both can result in premature cable failure, and downtime and costs for cable replacement. When in doubt about the selection, contact a trusted robotic integrator, robotic GMAW gun manufacturer or welding distributor for assistance. 

Companies should also look for sturdy power cables that are able to withstand UV damage from the arc and resist wear, as well as those with quick-change features to further extend cable life, simplify changeover and prevent interruptions to the welding process. 

Using high-quality consumables — nozzles, contact tips and gas diffusers — is another way to improve the robotic welding operation and protect the robotic GMAW gun. For higher-amperage applications, companies may want to consider a chrome zirconium contact tip to withstand the higher heat levels. The connections between consumables should always be tight to prevent electrical resistance that could lead to failure and to gain good conductivity for a smooth and stable arc. When possible, adding a nozzle cleaning station or reamer to the robotic weld cell can further optimize the performance of the consumables and the robotic GMAW gun by ensuring that the nozzle is free of spatter and able to direct the shielding gas to the weld pool to protect the weld. It can also help minimize the risk of the consumables overheating. 

Maintaining tool center point

In certain instances, companies may reprogram the robot after a collision in order to re-establish tool center point (TCP) with a bent robotic GMAW gun neck. As an alternative, a neck checking fixture (or neck inspection fixture) can adjust the neck back to the correct TCP to help improve the performance of the gun and gain greater arc-on time. The neck checking fixture tests the neck profile to ensure that the contact tip will meet the TCP. If the tool point is off because of an impact or other problem, it readjusts the neck back to the correct position. This peripheral can also be used to inspect a new robotic GMAW gun neck prior to installation to ensure it is accurate. For companies that maintain a large number of robotic welding cells, a neck checking fixture can reduce downtime and costs when exchanging necks from one robotic GMAW gun to another — welding operators need only to remove the damaged or bent neck and replace it with a spare one that has been inspected already to get the robot back to welding immediately. The damaged neck can then be set aside for adjustments while the robot is already online. 

For newer robots with more sophisticated collision detection software, using a solid mount to protect the gun in the event of an impact can also help maintain a more accurate TCP than a clutch mount. Unlike a clutch mount that is designed to move, these durable, high-strength mounts offer greater repeatability for higher weld quality. They are also less expensive. 

Adding to welding performance

To help maintain accuracy, quality and speed in the robotic welding operation, additions to the robotic GMAW gun like air blast and wire brake features are beneficial.

An option for both air- and water-cooled robotic GMAW guns, the air blast feature forces high-pressure air through the front of the gun to help remove debris that could enter the weld pool and negatively affect weld quality. Welding operators can program the air blast feature to operate between weld cycles to reduce unnecessary downtime. 

Another option for robotic GMAW guns to help optimize welding performance is the addition of a wire brake feature. As its name implies, a wire brake prevents wire feeding when welding stops. The result is a consistent wire extension at the beginning of every weld, a factor that especially complements robots using touch-sensing software — the wire brake keeps the wire in position as the robot searches for the weld joint location. This optional robotic GMAW gun feature also keeps the wire from unspooling during arc starting and stops. 

Robotic GMAW gun maintenance

Preventive maintenance (PM) is critical for gaining optimal performance from a robotic GMAW gun, whether it is air- or water-cooled or a conventional or through-arm style. 

Recommend PM activities include:

• Secure connections on a regular basis. Tighten front-end consumables and be certain that all seals are in good condition.
• Remove spatter from the nozzle regularly, ideally applying anti-spatter to protect against buildup. 
• Track the life span of the robotic GMAW gun liner and replace prior to failure. Trim replacement liners to the appropriate length using a liner gauge.
• Make certain that the power pin is secure.
• Check that welding cable leads are secured and look for signs of wear. Replace as necessary. 

The frequency of the PM schedule will depend on the size of the robotic welding operation and the application. Companies with large weldments on thick materials stand to have greater costs and downtime for rework should the gun fail and cause a quality issue. Maintaining the robotic GMAW gun more frequently is advised. 

Water-Cooled Robotic MIG Guns Can Reduce Consumable Costs and Downtime

For some fabricators, the choice between an air-cooled or a water-cooled robotic MIG welding gun is simple. Some heavy-duty applications simply demand a water-cooled model due to the high amperage and duty cycle requirements of the job — performance requirements that would cause an air-cooled gun to quickly overheat and fail.          

However, there are other less conventional robotic welding applications that may benefit from using a water-cooled MIG gun, too, and can contribute to much lower consumable costs and greater productivity. Water-cooled MIG guns typically have higher duty cycles and amperages, meaning they can be run for longer periods of time without stopping. Cooler guns mean cooler front-end consumables. In particular, it is possible to greatly extend contact tip life with these guns compared to air-cooled models. 

Deciding which system is the best choice involves careful analysis of several factors. In addition to amperage requirements and duty cycle, a fabricator should consider the up-front costs, potential return on investment (ROI) and the application specifics. Some fabricators may choose water-cooled robotic MIG guns based on the length of welds — the long arc-on time needed to produce these welds generates more heat in the gun. Similarly, critical start and stop points along a longer weld joint typically require a gun that can handle the extended amount of welding.

Considering the weld joint design and the material type and thickness, as well as joint access can also factor into whether to choose a water-cooled MIG gun. For example, aluminum or heavy plate sections that have been pre-heated can generate substantial radiant heat that affects the cooling of the gun and can adversely affect the life of the front-end consumables. A water-cooled gun can help here.

Some water-cooled robotic MIG guns have smaller diameter necks than air-cooled model due to optimized cooling capacity that requires less copper in the neck. As a result, they can reach into tighter spaces, through complex tooling restraints or into parts with access holes. When deciding whether a water-cooled robotic MIG gun is the best choice, it’s important to keep in mind that these products require more maintenance and often have a higher up-front cost.  It is necessary to weigh those factors against the productivity gains and savings that can result from longer consumable life.

Understanding water-cooled MIG guns

Keeping MIG welding equipment cool is necessary to protect the power cable, gun body, neck and consumables from damage due to the radiant heat from the arc and the resistive heat from the electrical components in the welding circuit.

A traditional water-cooled robotic MIG gun circulates a coolant from a radiator unit through cooling hoses inside the power cable and into the gun body and neck. The coolant returns to the radiator where the radiator’s baffling system releases the heat absorbed by the coolant. There are guns available on the market today, however, that cool only the front of the gun where heat is generated and still use an air-cooled cable. These features help save costs and eliminate potential leaks from the cable bundle where excess movements from whipping and repetitive motion create the greatest wear.

These features contrast to a completely air-cooled MIG welding system, which relies solely on the ambient air and shielding gas to dissipate heat that builds up along the length of the welding circuit. Air-cooled systems use much thicker copper cables, and inner neck tubes; water-cooled robotic MIG guns use much less copper in the power cables and thinner wall sections in the necks because the cooling solution carries away the resistive heat before it builds up.      

In general, water-cooled robotic MIG guns are beneficial for high-amperage applications and are typically available in 300 to 600 amp models. Closely related to amperage is duty cycle, which refers to the amount of time during a 10-minute cycle that the gun can operate at its rated capacity without overheating. Water-cooled robotic MIG guns can have varying duty cycle capacity depending on the manufacturer and model.                                                                                 

The amperage requirements, the length of time the arc is actually operating, and how the system will deal with the heat of welding in a specific application are among the most important considerations when choosing a water-cooled robotic MIG gun.  

Selecting a water-cooled robotic MIG gun

When choosing a water-cooled robotic MIG gun, be sure to select a product and consumables that use high quality materials that can handle high heat.

Guns on the market come in two styles: conventional and through-arm versions.Through-arm robotic MIG guns carry the cable assembly through the arm of the robot. This style can offer greater protection since the arm of the robot shields the power cable from abrasive wear and minimizes cable whipping during air moves. It’s important to know if the robotic arm is a conventional or through-arm style, so the gun and associated mounting bracket can be chosen to match. Knowing the robot model is also important for proper mounting hardware and insulating of the gun from the robot wrist.

As with air-cooled applications, make sure during installation that the selected water-cooled robotic MIG gun allows proper joint access. Having a neck design with the proper geometry that accesses the joint with the appropriate travel and work angles can prevent poor weld quality and/or the need to re-tool expensive fixtures, which could add downtime.

To make sure the cable bundle is the correct length, it’s also critical to know where the wire feeder will be located on the robot. If a cable bundle is too short, it might stretch; if it’s too long, it could interfere with opposing structures and also fail prematurely due to excess flexing.

Some water-cooled robotic MIG guns on the market have features that make them especially easy to use and to integrate into the robotic welding system. One available feature is the quarter-turn connection, which helps establish a quick and tight connection to help maintain good conductivity and prevent shielding gas leaks. Models with the quarter-turn connection feature are designed to seat the connection properly once a quarter turn is made, making it much easier and faster to change the neck.

Water-cooled robotic MIG guns with this quarter-turn connection feature also offer an automatic shutoff valve, to shut off the water flow any time the neck is changed, which helps simplify routine maintenance. Consider adding a flow switch to a system with water-cooled robotic MIG gun. These switches ensure water is flowing through the system; if the system doesn’t detect the flow of water in the gun, it will shut down and give an error message. Operating a gun without water flow will very quickly cause a catastrophic failure. All of this means added downtime and costly repairs.

Maintenance and usage tips

Water-cooled robotic MIG guns do require more maintenance than air-cooled models, since the presence of the water circuit introduces more potential issues. For example, if a hose or the neck is leaking, coolant could drip into the molten weld pool, leading to porosity and costly rework. It’s a good idea to conduct preventive maintenance each day or before the start of each shift. Just as with any welding system, it’s important to inspect a water-cooled robotic MIG gun to ensure that all consumables and connections are tight and working properly. Inspect the water lines frequently to make sure they are tight and have no leaks, and replace the O-rings when necessary (e.g., when cracks or wear appears).

Using an automatic reamer or nozzle cleaning station adds significant benefits to the preventive maintenance of water-cooled robotic MIG guns. A reamer eliminates the need to manually clean out the front-end consumables and can, with the addition of an automated sprayer, add anti-spatter compound to help extend consumable life further. This feature adds to the overall cost of the equipment, but helps increase uptime for production, with less manual intervention, and offers a solid return on investment in most robotic welding operations.

Do not fall prey to the notion that it is cheaper to use tap water in a water-cooled gun, as it can cause algae growth or mineral build-up and eventually clogging. Instead, use deionized water or the specially treated coolant solution recommended by the manufacturer. These coolants contain special additives to lubricate internal pumps and O-rings, as well as to prevent algae growth. 

Consider the return on investment

Choosing a water-cooled robotic MIG gun is often a necessity because of the demands of the application. A water-cooled model requires more up-front investment and more maintenance, but it can provide significantly longer consumable life and increased productivity from fewer consumable changeovers. Consider the various costs, specific application needs and accessibility to decide if a water-cooled robotic MIG gun offers a good option for a specific robotic application. Often a welding distributor, welding equipment manufacturer or robotic welding system integrator can help. 

Trends Associated with Robotic Welding Guns

Manufacturing and fabrication environments are dynamic, ever changing with the economy, customer demands, available labor and skill sets, and competitive forces, among other factors. To maintain a favorable position in the industry, it is critical for companies to continually look for ways to increase efficiencies while also improving quality and decreasing costs. For many, that means a shift toward welding automation, which has experienced its own changes in the last 10 years.  

During this time, robotic welding manufacturers have transitioned away from the manufacture of conventional robotic welding systems to the development of through-arm styles, in which the power cable of the robotic MIG gun runs through the arm of the robot as opposed to over top of it. These are now the prevalent robot styles in the industry and this change has had a direct impact on the design of the robotic MIG guns for the marketplace. But it is not the only trend associated with robotic MIG guns. Like any component of the welding operation, this equipment has continued to evolve to the demands of the industry and to provide solutions to improve the business of welding.

The through-arm benefits

Improving and simplifying cable management has been the driving force behind the shift toward through-arm robots and, therefore, the development of through-arm robotic MIG guns to accompany them. With conventional style robots and guns, the cable is prone to “whipping” during air movements, which causes undue stress on this portion of the gun, and can lead to premature wear and failure caused by the cable rubbing against the robot or tooling. It also creates additional cost and time for companies to implement cable management systems. 

The through-arm style robot and through-arm robotic MIG gun make it easier for companies to minimize downtime associated with cable management and reduce costs for cable replacement. It also eliminates the risk of selecting the wrong cable length, a common mistake that occurs with conventional robotic MIG guns. The through-arm robot model dictates the length of the robotic MIG gun cable, so there is no concern about it being too long (which requires extra cable management or could cause wire feeding issues) or being too short (which can cause the cable to stretch and fail prematurely) — both issues associated with conventional robotic MIG guns. 

There are other benefits to the shift to through-arm robots and through-arm robotic MIG guns, namely that they can accommodate for increases in welding speed that are also becoming customary in the industry. Robots are getting much faster, but with the through-arm robot there is no longer the concern of the robotic MIG gun cable getting caught on tooling during quick movements.

Too, it is easier to complete offline robot programming or welding simulation and have it work with these robots because there is less concern about having to accommodate for clearance for the power cable in an application. If a robotic MIG gun fitted for a through-arm robot works in simulation, it will most likely work in the real-world application. 

Increased cable durability, simplified replacement

As companies strive for greater arc-on time and higher productivity, robotic MIG gun manufacturers are helping by providing increasingly more durable power cables on this equipment and implementing features that simplify cable changeover. Some manufacturers offer a rotating power connection on the front of the cable that allows the robot to spin on its final axis as much as necessary without binding the cable. This feature helps minimize stress due to routine torsion and to extend the life of this part of the gun, as well as to increase the robot’s operating range by allowing it to rotate a full 720 degrees (360 degrees in both directions) and weld faster.

Built-in quick-change features on many robotic MIG guns also expedite cable replacement, adding to the operation’s productivity, while the use of stronger cable materials help better resist wear and UV damage from the arc for longer component life. 

Utilizing solid mounts

Another trend associated with robotic MIG guns is the use of solid mounts (also called solid arm mounts) as opposed to the clutch mounts that were used previously to protect the gun in the event of a collision — an occurrence commonly caused by an incorrectly position work piece or tooling that has been left out of position, among other factors. This trend is due to more sophisticated collision detection software being built into today’s robots. This software is increasingly capable of monitoring current rates and/or torque so it can quickly stop the robot when an impact occurs. Solid mounts are made from durable, high-strength aluminum alloys, and are an alternative to the clutches used with older robot models.

There are two key benefits to using a solid mount for robotic MIG guns compared to a clutch:

1. They offer greater repeatability for higher weld quality
2. They are less expensive. 

Clutches (also called shock sensors) are designed to recognize the physical impact of the robotic MIG gun on a solid surface during a collision and send an electrical signal back to the robot controller, causing the system to stop. While effective, clutches are designed to move, which can affect tool center point (TCP) after a collision. Also, since it is an electrical device, it costs more than a solid mount and is more prone to failure because of its internal components — expenses that many companies can now happily omit.  

Creating more space, better joint access

As companies seek ways to become more competitive and produce higher volumes of parts, they need to maximize floor space to make room for more robots to do the job. As a result, robots and welding cells are becoming smaller and in many instances, tooling has become more complex. These changes pose greater space constraints when it comes to the robotic MIG gun.

Many robotic MIG gun manufacturers have responded to this trend by creating guns that provide a more open work envelope around the mounting arm (the depth from the wrist of the robot to the tip of the robotic MIG gun) so maneuvering around tooling and gaining joint access becomes less cumbersome.

There are also more options for neck lengths and angles available for robotic MIG guns, which helps companies gain access to complicated joints. 

More cooling options

Because many robotic welding applications tend toward higher amperages and longer arc-on times, it is critical for companies to have a robotic MIG gun that provides adequate amperage without overheating. The complexity and increased cost of water-cooled robotic MIG gun systems (compared to air-cooled models), however, make some companies wary of the investment for their high amperage applications. Too, if there is an issue with the coolant flow, there is the risk of the robotic MIG gun overheating and failing — an event that can be costly not just for replacement of the gun, but also potentially for rework of the part should quality problems occur.

A development in recent years that addresses this concern is a hybrid robotic MIG gun. This type of gun has a durable neck like an air-cooled model and water lines that run external to the neck down to the nozzle. Should the coolant flow fail, the gun can rely on the underlying air-cooled unicable to provide enough current-carrying capacity for the job for a period of time, saving downtime and costs to address a complete robotic MIG gun failure. These guns also offer the higher amperage associated with a standard water-cooled gun, making them a good option for companies who need greater cooling capacity for an application. 

Adding the extras

Because time is at a premium when it comes to robotic welding, companies are always looking for ways to extend their robotic welding cycle time — down to the second. To help maintain greater arc-on time while still protecting the robotic MIG gun and consumables from spatter build-up that could affect weld quality, adding air blast to robotic MIG guns is becoming a popular choice with some companies. This optional feature can be added to the robotic MIG gun and functions by blowing compressed air through the gun at a high pressure (approximately 100 pounds per square inch — psi) to clear debris loose in the front end while the robot is moving out of the way so the table/fixture can index. This addition can help companies reduce the number of times that the robotic MIG gun needs to be reamed out by a reamer or nozzle cleaning station, resulting in more arc-on time and greater productivity. 

More to come

While robotic MIG guns may seem like a small part of the whole automated system, their design and functionality can have a significant impact on the cost, productivity and quality of an application. The trends discussed here are just some of the ways that robotic MIG gun manufacturers have adjusted the designs and capacity of the products to help companies gain the best results in recent years. As with any piece of welding equipment, robotic MIG guns will need to continue evolving just like any equipment in order to meet companies’ changing needs and to meet the demands of the fabrication and manufacturing industry. 

 5 Things to Know About Robotic MIG Guns

Consider some of the top things to know about robotic MIG guns as a way to get the most out of this equipment. When it comes to robotic welding, precision, repeatability and speed are essential to ensuring a successful outcome in the operation. In order to gain the best benefits, companies rely on the robot’s ability to execute the same weld, exactly the same way and as fast as possible. And while the robot itself, proper programming and oversight by a trained welding supervisor are all important components in the robotic welding operation, the robotic MIG gun also has a direct impact on quality and productivity, as well as costs. 

This article has been published as a web-exclusive on thefabricator.com. To read the entire story by Tregaskiss technical support specialist, Tom Whitter, please click here. 

Equipment, Training, Maintenance and More: Best Practices for Successful Robotic Welding

Estimated reading time: 11 minutes

The cost to implement welding automation can be substantial, requiring companies to plan out the purchase carefully and to justify the expenditure to the appropriate financial or management personnel. The payback on the investment, however, can be equally beneficial. From productivity increases to quality improvements and cost savings, companies can often position themselves for greater competitiveness in the marketplace by adding robotic welding systems to their welding operation or by replacing manual welding cells altogether.                                    

Unlike companies that employ semi-automatic welding, those with robotic welding systems have the added responsibility of protecting the large capital investment in the equipment. But no two robotic welding systems are the same and likewise, there is no single step to ensure a successful outcome. Rather, a combination of the appropriate planning, equipment purchases and personnel training — among many other things — provides the best results. Paying close attention to the daily occurrences in a robotic welding cell and engaging regularly in some of the best practices discussed here can also help provide high quality results.

Manage parts and workflow

Companies typically invest in welding automation to expedite the welding process, gain more consistent weld quality and/or to reduce costs. The process can also set companies apart from the competition by allowing for faster completion and delivery of products. For companies with high-volume demands and low-variation parts, robotic welding can become an important part of their production plans. Smaller companies with lower-volume, high-variety parts can also benefit, but they may require more flexible tooling and more programming time to accommodate for several types of products.       

The important consideration for both high- and low-volume production is to ensure that the parts to be welded lend themselves appropriately to an automated welding process. Robotic welding systems rely on consistent parts to provide consistent results. Companies that have or are planning to implement a robotic welding system need to be certain that parts are simple and repeatable. The presence of gaps, poor fit-up or poor joint access can have a detrimental impact on the high quality sought with robotic welding systems.                                        

Similar to a semi-automatic welding application, consistent workflow is also important for a successful robotic welding operation, with the main difference being the speed at which parts are delivered and welded since a robotic system is so much faster. The parts need to enter and leave the cell at a quicker and steadier rate — without bottlenecks — to gain optimal throughput.           

Companies should assess each activity leading up to the part entering the cell, making sure that the supply of parts matches the robot’s cycle time, and also assess the steps for handling the part after it leaves. In some cases, it may be necessary to change how the parts are fabricated upstream and completed downstream (e.g., finishing, painting, etc.) to establish good workflow. Companies should also look to eliminate non-value added activities, including excessive lifting or handling of parts, and avoid multiple trips to stack products or other similar activities.

Protect against premature component failures

Robotic welding systems typically operate at higher amperages and longer duty cycles than semi-automatic welding operations — the robots can withstand the greater arc-on time and heat compared to a human operator. While those increases are excellent for supporting high productivity, the additional heat and welding duration can be especially harsh on consumables — nozzles, contact tips and gas diffusers (or retaining heads).    

Companies need to take steps to avoid the pitfall of excessive consumable changeover. Entering the weld cell for purposes other than part changeover or routine pauses in the operation can add unnecessarily to downtime, which can easily add up per shift, day, month and year, resulting in lost productivity. Excessive consumable changeover is also costly, as it increases inventory and inventory management.            

There are two key steps companies can take steps to increase consumable life in their robotic applications and reduce downtime. One, install consumables properly and maintain tight connections throughout the course of welding.  Loose connections increase electrical resistance, causing the consumables to generate additional heat that can shorten their lifespan and/or cause them to perform poorly. Follow the manufacturer’s instructions for proper consumable installation, taking care to tighten the consumables appropriately. It’s also a good idea to check the consumables periodically during routine pauses in welding, as they can loosen throughout a shift.

Two, install the robotic MIG gun liner properly, as this helps prevent downtime to address wire feeding issues or to correct a burnback, in which the wire “burns back” into the contact tip. Follow the manufacturer’s instructions for trimming and installation, using a liner gauge to confirm the correct liner length.                   

Preventing premature power cable failure, which can occur in both through-arm robotic welding systems (where the cable feeds through the arm of the robot) or in standard robotic welding systems (also referred to as over-the-arm) is also important. Be mindful of the path the robot has been programmed to follow, the speed at which it moves and the cable length. The power cable should clear the robotic arm and tooling to prevent it from catching or rubbing against either part. Also, the robot should be programmed not to move too fast or abruptly. Aggressive movements can cause the power cable to snap. Make sure that the cable is the appropriate length — too short of a cable can stretch beyond its capacity during routine robotic movements, leading to greater wear. If the power cable is too long, it may be prone to kinking or becoming pinched by the robot’s arm. 

Don’t neglect maintenance?

Preventive maintenance (PM) programs are among the most effective best practices a company can instill for a robotic welding system. Ideally, PM programs should cover every aspect of the system — from the robot to the contact tip. Proper PM activities can help prevent unscheduled downtime, low quality parts, costly repairs and/or equipment replacements.

Companies will need to assess their PM needs on an individual basis and engage a maintenance team or other personnel to carry out the activities at the appropriate times and intervals. As a general rule, companies that weld thick materials or have applications with long, continuous welds common in welding automation can benefit from more frequent PM activities, as the rework for quality issues can generate much more costly rework compared to an application producing multiple smaller parts. Several PM activities can occur during routine pauses in production, including:

•    Cleaning the robot and fixturing to prevent the buildup of dirt, debris or anti-spatter compound, which could affect part fit-up.
•    Checking for tight consumables connections.
•    Confirming tool center point or TCP (discussed in more detail later).
•    Checking for power cable wear and replacing as needed.

Other activities that happen less frequently like greasing the robots joints can be completed during a longer scheduled stop.

Always consider peripherals and robotic MIG gun extras

Peripherals are often an overlooked part of the robotic welding system. The added cost of this equipment, which includes nozzle cleaning stations (also called reamers or spatter cleaners), is frequently considered an unnecessary expense. In reality, this equipment can maximize robotic welding performance and help companies gain a better return on investment (ROI) from their robotic welding system.

As its name suggests, a nozzle cleaning station cleans the nozzle of dirt, debris and spatter, typically during routine pauses in the robotic welding operation. The goal of this cleaning action is to help ensure consistent shielding gas coverage, and with it, reduce weld defects, expensive rework and lost productivity. A nozzle cleaning station also helps extend the life of consumables, minimizing the downtime and expense for changeover.

For the best results, the nozzle cleaning station should be mounted in close proximity to the robot to reduce the amount of time necessary for its arm to reach it. Companies can mount the peripheral overhead if need be. The robot should be programmed to clamp onto the nozzle cleaning station at a taught position exactly perpendicular to the cutting blade that clears out the spatter or other debris. Any misalignment to the position of the nozzle could lead to partial cleaning of the nozzle and excessive spatter build-up. Program the robot to go to the nozzle cleaning station as often as possible; the cleaner the consumables are, generally the better performing and longer lasting they will be.

For companies who choose to attach an anti-spatter sprayer, it’s important to locate the spray in the appropriate position so it completely coats the inside of the nozzle. Ideally the outside should be covered to within three-quarters of an inch from the bottom of the nozzle.

Other peripherals that companies can integrate into their robotic welding system include a wire cutter and a neck inspection tool (discussed in the next section). A wire cutter cuts the welding wire to a specified length, removing any inconsistencies at the end, providing for more reliable and smoother arc starts and better seam tracking for robots featuring that technology. For companies using touch sensing software, using a wire cutter in conjunction with a robotic MIG gun featuring a wire brake can help prevent problems with seam tracking. Touch sensing allows the robot to store position data and send electrical impulses back to the controller once it has located the joint. For applications that have slight variations in parts, touch sensing helps maintain weld consistency. It is also more cost-effective than investing in new tooling and fixturing to hold a part in a precise location; if the part moves slightly, the robot can still locate the joint and weld accurately, as long as the joint has well-defined edges. Using a wire cutter can ensure the wire is cut to a consistent length; the wire brake holds the wire in a set position as the robot articulates and searches for the weld joint, ensuring more accurate touch sensing readings for more consistent weld quality.

Stay on target

For a robot to be repeatable and provide consistent welds, it is important for the system to maintain its tool center point or TCP, which is the focal point of the robotic MIG gun and its relationship with the position of the welding wire in the joint (gun-to-work distance).

Typically, but not always, TCP issues occur after a collision, during which the neck of the robotic MIG gun becomes bent. To rectify the issue, welding operators can employ a peripheral called a neck inspection tool (or neck-checking tool) to bend the neck back to the proper angle. Most neck inspection tools are designed to accommodate standard necks for a particular brand of robotic gun. To use this peripheral, the welding operator or maintenance personnel needs to determine the tolerances for the robotic welding program and adjust the bent neck to meet the correct specifications.

To maintain TCP, it is also important to install the robotic MIG gun neck properly, making sure it is fully seated. If not, it will extend too far and can cause TCP to be compromised. Programming the robot for a TCP check to verify proper position can also help prevent against quality issues and potential downtime.

Another best practice to help ensure on-location welds is to check that fixturing is in the correct place, that it doesn’t allow the parts to move and that the base of the robot is securely in place. Periodically check that part variation hasn’t changed, as well.

Find the right people

Designing parts for automation, managing workflow, selecting the right equipment and implementing a consistent PM program mean nothing if companies don’t have the right personnel in place to work with and/or oversee the robotic welding system. Investing in the people who are responsible for interacting with the robotic welding system should always be a priority.

Skilled welding operators or employees with previous robotic welding experience are often a good choice for overseeing a robotic welding system. The personnel should undergo the proper up-front training before taking on the responsibility of working with the robotic welding system — loading and unloading parts and programming the robot for instance. Robotic welding integrators and robot manufacturers can often provide OEM-based training and continuing education. The goal is to instill the skills necessary not only to work with the robot on a daily basis, but also to be able to hone troubleshooting skills that can promote the maximum uptime in the robotic welding cell. These individuals can also be part of the PM programs mentioned earlier.

Protecting the investment

As with any capital investment, companies need to take the appropriate steps to protect their robotic welding system. Whether it’s the addition of peripherals or implementing additional training, engaging in a few best practices can help companies gain a solid payback on the equipment, empower employees to be part of the company’s success and establish the robotic welding system as a profitable part of their business. The items discussed here are by no means exhaustive. Companies can seek out ideas for improving their operation from other, non-competitive companies, or work with a trusted welding distributor or robotic integrator for further options.