Welding Gun Consumables – What You Need to Know

What is a MIG Gun Consumable?

Family product photo of AccuLock S, AccuLock R consumables systems

Welding gun consumables can be an overlooked part of the MIG welding system. As small components of a MIG welding gun, many users simply use whatever consumables come installed or are the least expensive to purchase. However, spending the time to carefully select, store, install, and maintain your gun consumables can pay off in terms of reduced costs, increased productivity and better weld quality.

Read on to learn everything you need to know about MIG welding consumables including tips, videos, product recommendations and more! 

Welding Gun Consumable Components

MIG gun consumables are the parts of the welding gun that wear with use and require ongoing replacement to ensure consistent weld quality. Consumable systems are comprised of the following components:

  1. Nozzle / gas cup
  2. Contact tip
  3. Gas Diffuser / retaining head
  4. Liner / conduit
  5. Power pin

It should be noted that only some MIG guns include the power pin as part of the consumable system. In these systems, the entire wire delivery path from the welding machine to the weld puddle has been fully optimized from a consumables perspective.

Nozzles (also known as Gas Cups)

Nozzles direct the flow of the shielding gas to the weld puddle.  In any welding application, the right material, shape and style of nozzle can have an impact on quality, productivity, and the cost of the welding operation.  

Nozzle Materials


AccuLock S Brass Nozzle with Short Taper
  • Ideal for lower amperage applications (100 to 300 amps)
  • Tend to resist spatter well


Copper Nozzle
  • Better for applications that are higher amperage (above 300 amps) or that have longer arc on times 

Plated Copper

Quik Tip Plated Nozzle
  • Show the most benefits (spatter resistance) when used with water-cooled MIG guns
  • Plating may be chrome or nickel
Group of four different style Tregaskiss nozzles

Nozzle Shapes

The best choice is to use as long and large of a nozzle as possible that still allows access to the weld joint. One exception to this rule is when heavy spatter is expected (galvanized base metal, oily surface, short circuit well, 100% CO2, etc.) – in this case try a short nozzle with a larger bore size.  Maximizing the nozzle size vs weld access helps ensure the greatest shielding gas flow and also helps prevent sticking the contact tip to the workpiece or table in manual welding applications. Larger nozzles are also less prone to collecting spatter compared to those with smaller inside diameters. 


  • Largest inside diameter for good gas flow / coverage  
  • May not provide enough access to some welds 
  • Is the best choice for use with robotic nozzle cleaning stations 


  • Smaller inside diameter  
  • Offers better weld access 
  • Long tapers are more likely to accumulate spatter – when possible choose a short taper nozzle instead 
  • Tapered nozzles are also thinner through the tapered area and less able to withstand higher amperage or higher-duty-cycle applications


  • Smaller outside diameter  
  • Offers better weld access

Nozzle Connection Styles

Nozzles for MIG welding guns are available in several connection styles:


  •  Slides onto the gas diffuser 
  • Are faster and easier to remove and replace than thread-on nozzles 


  • Threads onto the MIG gun gas diffuser or neck 
  • Offers certainty that the nozzle is fully seated  


  • Comprised of a nozzle body and a cone 
  • Allows replacement of just the front end of the nozzle (cone) which is the primary area of wear
  • Cones usually thread into the nozzle body

Contact Tips

Contact tips are responsible for transferring the weld power to the wire as it passes through to create the arc. This means that its connection with the gas diffuser is critical to ensure good electrical conductivity. A tapered connection is preferred for this reason since it helps to hold the tip securely and accurately in position. The material, size and style of the contact tip also have a role to play in how it performs in any given welding application.  

Contact Tip Materials

  1. Copper contact tips are the most common and are suitable for most MIG welding applications.  
  2. Chrome zirconium contact tips are used in more demanding welding applications. As a general rule of thumb, they last approximately twice as long as copper tips.  
  3. HDP contact tips have an insert at the front of the tip that is comprised of a special alloy that resists both mechanical and electrical wear. This allows them to last 6-10x longer than copper and chrome zirconium contact tips and are ideal for pulsed welding applications. 

Contact Tip Sizes

Both the outside size and shape and the inside diameter of the contact tip can impact its performance:

Outside Diameter Considerations

  • The diameter of the contact tip can be indicative of its duty rating – thicker contact tips can withstand more heat  
  • Care must be taken to ensure there is good clearance between the contact tip and the nozzle interior to ensure good gas flow
  • Tapered contact tips can be used in cases where clearance and weld access may be an issue

Inside Diameter Considerations

  • The inside diameter of the tip is sized to match commercially available welding wire sizes
  • Contact tips that are too large for the wire will allow the wire to wander or the arc to become unstable 
  • Contact tips that are too small will cause too much friction resulting in wire feeding issues 
  • When using a 500-pound barrel or greater of wire, it’s recommended to undersize most copper and chrome zirconium contact tips by a single wire size due to the larger wire cast (i.e. .040″ tips for 500 lb drums of .045″ wire)

Contact Tip Styles

AccuLock Copper Contact Tip

Threaded contact tips screw into the diffuser and should be tightened into place with a tool. Look for coarse threads that speed replacement. 

Centerfire contact tip shown from front

Drop-in contact tips are threadless and are usually held in place by the nozzle or other consumable parts.  They do not require the use of tools for installation.

Gas Diffusers (also known as Retaining Heads)

AccuLock R thread-on diffuser

Gas diffusers are designed to conduct electricity to the contact tip while distributing the shielding gas.  Mechanically, they also hold the contact tip and nozzle in place on the gun’s neck.   

poorly designed diffuser might: 

  • Have gas holes that clog frequently, or are not reachable by nozzle cleaning station cutter blades, leading to porosity 
  • Channel the shielding gas improperly resulting in turbulent gas flow and unbalanced gas coverage 
  • Allow connections with the tip, nozzle or neck to loosen frequently resulting in high electrical resistance and additional heat

Liners (also known as Conduit)

The liner’s job in MIG welding is to guide the welding wire from the welding machine and/or wire feeder, through the gun cable and through the contact tip. Choosing the right size, type, material, and quality of liner and then installing it correctly is necessary for good welding performance. 

Types of liners 

  1. Conventional liners are replaced from the back of the MIG gun and are the most common type of gun liner used today.
  1. Front-loading liners load from the front of the MIG gun without disturbing the wire or wire feeder connection. They can be replaced in half the time it takes to replace a conventional liner.  These are ideal for MIG guns used in robotic or boom-mounted applications.
  1. Jump liners – Part of a three piece system, a short liner (jump liner) is used through the neck of the gun where most of the internal wear occurs.  An adapter joins this short front liner to the longer rear liner.  A jump liner is ideal for welders who frequently change their gun necks, run nylon liners (for aluminum wire) or utilize a wire brake (automated applications requiring touch sensing). 
  1. Dual-locked liners – these liners are locked in place at the front and back of the welding gun to prevent gaps and misalignments along the wire feed path. 

Power Pins

Acculock S Power Pin Cap

Power pins provide a direct connection for wire, weld power and gas flow between the welding machine and/or wire feeder and the MIG gun.  The power pin also determines a MIG gun’s compatibility with a given welding machine.  An accurate gun to machine connection is critical to ensure that the welding wire (also known as filler metal), gas and weld power are passed efficiently to the MIG gun.  

Power pins are generally very durable and are the most infrequently replaced consumable part due to wear.  However, a welder may choose to replace their power pin with a different one so that they can use a single gun on different machines.     

Similarly, a company with more than one brand of welding machine could configure their gun fleet with different power pins allowing them to consolidate their MIG gun and consumables inventory.  The related benefits include: 

  • Simplified welder training  
  • Easier product maintenance  
  • Reduced consumable replacement errors 
  • Reduced inventory for replacement guns

A few additional points to understand:

  • Shielding gas may run through the power pin or externally via a separate line 
  • Some power pins have additional features such as a locking power pin cap that holds and positions the liner for optimized wire feeding through the gun
  • Power pin caps may have a specified wire size range – please consult your owner’s manual when making a significant change in wire size

Selecting Welding Gun Consumables: Which Ones Are Right For You?

MIG gun consumables must be carefully selected to meet the needs of your welding applications and your overall business.  Many variables should be taken into consideration when making your selections.  Here are a few questions to consider: 

Shape and Size 

  • Optimize Weld Access: Are tapered nozzles and/or contact tips needed to allow better weld access? 
  • Ensure Good Gas Coverage: Is there enough internal clearance between your nozzle and contact tip for good shielding gas flow?
  • Maximize Lifespan: Are your consumables an appropriate duty level for your application i.e. are they wearing out too quickly? 
  • Optimize Wire Feeding: Is your contact tip the right size internally for your welding wire?  


  • Minimize Spatter / Maximize Lifespan: Does your nozzle material provide the right balance of durability and spatter resistance for your application?  
  • Minimize Spatter: Material quality and finish for front-end consumables should also be considered. If your consumables have rough edges or many imperfections, they will accumulate spatter more easily.
  • Maximize Lifespan / Minimize Downtime: If your welding application is experiencing too much downtime for contact tip changes, it might be time to consider a contact tip material change. Robotic welding operations are most sensitive to downtime events so particular care must be taken when selecting contact tips for this application. 

Connection Style


  • Minimize Spatter / Maximize Lifespan: Should your contact tip be recessed, flush with, or sticking out of your nozzle? 

Liner Type

Have you considered all the liner options out there to ensure you have the right one for your operation?


If you have many welding guns, using as many common consumables parts as possible can ease employee training requirements, help to prevent replacement errors, and reduce inventory carrying costs.

  • Minimize Costs: The more consumable parts you have in inventory, the higher your carrying costs will be.
  • Minimize Errors / Minimize Training: Are you experiencing a high number of consumables replacement errors because your consumables inventory is complex and confusing for your welding operators?

Storing, Installing and Maintaining MIG Welding Gun Consumables

For MIG consumables, several pitfalls exist that can shorten their lifespan. Taking the time to learn tips for properly storing, installing and maintaining them can positively affect productivity, quality, and the bottom line. 

Storing MIG Gun Consumables

  • Always keep MIG consumables in their original packaging until they are ready for use. Opening them and placing them in a bin can lead to scratches or dents that allow spatter to adhere and will ultimately shorten the products’ life. It will also allow them to oxidize which can increase electrical resistance. 
  • Keep storage containers for new consumables separate from those for discarded ones to avoid selecting an old contact tip or nozzle that may have dents or scratches and be prone to spatter accumulation.  

Installing MIG Gun Consumables

  • Always follow the MIG consumable manufacturer’s instructions for consumable installation. 
  • Always wear clean gloves when handling or replacing contact tips, nozzles, diffusers and liners to prevent dirt, oil, or other contaminants from adhering to them.  Similarly, avoid dragging liners on the ground as this can contaminate the weld and hinder consumable performance. 
  • Use a pair of welder’s pliers (welpers) or other recommended installation tools to install contact tips and diffusers. Never use wire cutters or side cutters, as too much pressure from these tools can damage the inside diameter of the contact tip. These tools also tend to scratch the surface of the consumables, leaving marks that attract spatter. 

Maintaining MIG Gun Consumables

  • Inspect consumables periodically for good connections.  This minimizes the chance of poor conductivity and the spatter accumulation or premature failure that can result. 
  • When used sparingly, anti-spatter solution can help keep MIG consumables clean and prolong their life in both semi-automatic and robotic welding applications. 

Solving Issues with MIG Welding Gun Consumables

Although they are not always the root cause of welding issues, MIG gun consumables are often the first to be checked or replaced during troubleshooting due to their low cost and ease of access.  The following welding issues may be addressed via MIG gun consumables (items in italics are additional potential root causes that are NOT related to gun consumables)

  1. Contact Tip Burnback
    This failure mode occurs when the welding wire melts back into the contact tip interior blocking feeding.  Possible root causes include: 
    • Liner trimmed incorrectly can lead to gaps and friction at liner junctions and debris buildup in liner / contact tip  
    • Contact tip too small for the wire 
    • Improper tip stickout 
    • Erratic wire feeding
    • Loose connections (tip / diffuser / neck) 
    • Improper wire stickout 
    • Improper voltage and/or wire feed speed 
    • Faulty ground 
  1. Wire Does Not Feed / Erratic Wire Feeding
    This is when the filler metal will not move backward or forward or it moves inconsistently. 
    • Liner trimmed incorrectly can lead to gaps and friction at liner junctions and debris buildup in liner / contact tip 
    • Wrong size contact tip 
    • Worn or dirty contact tip 
    • Contact tip burnback 
    • Wrong size liner  
    • Bird nest 
    • Feeder / relay malfunction 
    • Poor adaptor connection 
    • Worn or broken switch 
    • Improper drive roll size 
    • Drive roll tension misadjusted 
    • Worn drive roll 
    • Improper guide tube relationship 
    • Improper wire guide diameter 
Image of a wire melted with the contact tip badly damaged due to burnback
  1. Short Contact Tip Life 
    Burning through more contact tips per shift than usual can be a sign of one of these problems: 
    • Liner trimmed incorrectly can lead to gaps and friction at liner junctions – this can misalign the wire inside contact tip leading to contact tip keyholing  
    • Improper contact tip stickout position (stick-out vs. flush vs. recess)
    • Improper contact tip duty or material for application 
    • Contact tip burnback 
    • Erratic wire feeding 
    • Improper wire stickout 
    • Improper voltage and/or wire feed speed 
    • Faulty ground 
    • Poor quality welding wire
  1. Short Nozzle Life 
    Frequently replacing nozzles can be a sign of underlying issues.  These include: 
    • Nozzle is undersized for the application 
    • Nozzle loose or deformed due to being used as a chipping hammer  
    • Tapered and bottleneck shaped nozzles have an increased risk of spatter build-up due to the narrower bore which can shorten life
    • Incorrect contact tip recess can lead to erratic arc and increased spatter shortening life 
  1. Erratic Arc 
    Erratic arc can be heard and felt when welding by hand.  There will be excessive popping and crackling sounds from the arc and vibrations can be felt in the gun caused by wire chatter. 
    • Liner trimmed incorrectly can lead to gaps and friction at liner junctions 
    • Buildup inside the liner  
    • Wrong size contact tip 
    • Worn contact tip 
    • Not enough bend in gun’s neck 
Tip of a nozzle caked with spatter after welding
  1. Extreme Spatter
    Generating more spatter than usual can be caused by: 
    • Incorrect contact tip recess can lead to erratic arc and increased spatter
    • Poor / loose consumables connections
    • Improper machine parameters 
    • Improper gas shielding 
    • Contaminated wire or work piece
    • Poor / loose ground connections 
Image of porosity on a weld bead
  1. Porosity in Weld
    Small holes throughout the weld bead is called porosity.  This can be caused by: 
    • Nozzle insulator worn 
    • Nozzle plugged 
    • Gas diffuser damaged 
    • Gas diffuser gas holes plugged 
    • Worn, cut or missing o-rings 
    • Consumables are under-sized for the application 
    • Travel speed too fast
    • Poor position / approach angle
    • Bay doors open / breeze blowing through shop
    • Faulty solenoid 
    • No shielding gas 
    • Flow improperly set 
    • Ruptured gas hose 
    • Control circuit loss 
    • Loose fittings
  1. Birdnesting
    Welding wire may accumulate inside the welding machine or inside the welding gun resembling a bird’s nest.   
    • Liner trimmed incorrectly can lead to gaps and friction at liner junctions 
    • Buildup of debris in liner 
    • Wrong liner size  
    • Contact tip burnback 
    • Wrong contact tip size
    • Wrong power pin
    • Power pin / feeder misalignment 
    • Incorrect drive roll size or style 
    • Incorrect drive roll tension settings 
    • Worn drive rolls 

Surprised by how many welding issues are caused by improperly trimmed liners? Read below to learn more about why liner trim length is so critical to MIG welding success. 

Need potential solutions for the above issues?  View our Welding Troubleshooting Guide