Optimizing the robotic weld cell helps improve productivity, allowing a manufacturing facility to save time and money. It can be especially beneficial in applications that use pulsed gas metal arc welding (GMAW-P), a process that results in rapid wear to the welding gun’s front-end consumables.
While the choice of contact tip for the GMAW gun may seem like a small factor in the entire operation, consider how much time it takes for an operator to enter the weld cell and change the contact tip — and how many times per day the tip is changed in most robotic welding operations. For example, copper contact tips are changed on average four times per shift. In a three-shift operation averaging 10 minutes per tip change, that equates to spending two hours per day changing contact tips. What else could a welding operator be doing with this time to create value in the manufacturing operation?
|TOUGH LOCK™ HDP Contact Tips from Tregaskiss last more than 10 times longer than copper or chrome zirconium tips, allowing users to go from changing contact tips two to four times each shift to only changing the tips once every third shift or longer. |
There are contact tip innovations that help significantly reduce the downtime spent on changeover — time that can be spent on other tasks in the operation, such as increasing production up-time. In addition, when the operator spends less time in the weld cell, it reduces the potential of health and safety incidents and the possibility of weld quality issues through altering weld settings and parameters such as tool center point.
For these reasons, it’s important to consider the total cost of ownership when selecting the right contact tip for a robotic welding operation.
Demands of GMAW-P
As more manufacturing applications use thinner, lighter and more corrosion-resistant materials to meet industry demands, this increases the use of GMAW-P processes, which offer benefits for welding thin-gauge materials. Pulsed waveform technology continues to develop, offering faster travel speeds, reduced spatter levels and high weld quality in many robotic applications.
However, pulsed processes typically require a higher frequency of contact tip changeover due to the energy of the process. Faster contact tip deterioration is caused by peaks in pulse waveforms where the energy/heat is five times greater than in traditional constant voltage (CV) GMAW.
Because of this, arc erosion is a common failure for contact tips in GMAW-P. Contact tip failure increases an operation’s costs, due to the increased frequency of downtime related to tip changeover.
A new contact tip design has resulted in tips with improved resistance to arc erosion that last much longer in pulsed welding.
|HDP Contact Tips currently come in .035, .040 and .045 sizes and can be used with standard nozzles and TOUGH LOCK® Gas Diffusers, as well as with air-cooled guns or water-cooled guns.|
Contact tip advancements
Contact tips made from copper or copper chrome zirconium are commonly used in many welding applications. However, adoption of a GMAW-P process can double contact tip replacement frequency and related downtime when using copper or chrome zirconium tips.
A new innovative technology on the market today can significantly extend the time between contact tip changeover, thanks to a combination of proprietary materials and tip design. TOUGH LOCK™ HDP Contact Tips from Tregaskiss last more than 10 times longer than copper or chrome zirconium tips, allowing operations to go from changing contact tips two to four times each shift to only changing the tips once every third shift or longer.
HDP Contact Tips are engineered to resist wear better than other materials and designs previously used for contact tips, providing increased resistance to arc erosion in pulsed welding, as well as spray transfer and CV GMAW. The precise fit between the tip and the wire also results in good arc stability to help produce high-quality welds, and because the degradation of welding current from the power source to the contact tip is reduced, it provides a truer representation of the pulsed waveform program.
The tips currently come in .035, .040 and .045 sizes and can be used with standard nozzles and TOUGH LOCK® Gas Diffusers as well as with air-cooled guns or water-cooled guns. HDP Contact Tips can be used with Tregaskiss guns, as well as guns from other MIG welding gun manufacturers.
Because the tip bore is sized so tightly to the welding wire, it’s best to use the HDP Contact Tip with good-quality welding wire that has a large cast. A high-quality wire typically has a consistent wire diameter, which promotes better feeding and optimized performance.
Significant productivity gains
Typically, operations conduct contact tip changeovers on a preventive maintenance schedule to avoid unplanned downtime in the manufacturing process. The necessary frequency of contact tip changeover varies based on many factors including application, wire type and quality, waveform and base material.
Many robotic welding operations have 100 welding arcs or more and run three shifts per day. In robotic welding operations, copper tips are changed on average four times per shift — or 12 times per day. Chrome zirconium tips are changed about half as often, or six times per day. A scheduled contact tip change typically takes 10 to 15 minutes to complete.
Compare this to real-world results from several manufacturing operations using HDP Contact Tips. For example, one manufacturing operation converted to HDP Contact Tips in a solid wire GMAW-P application. The operation produces 600 parts per shift, and the previous chrome zirconium contact tip required changeover every 60 to 80 parts — or about 10 times per shift. In the company’s trial, one HDP Contact Tip was still running after 2,500 parts under the same parameters.
Another manufacturing operation running a standard GMAW process tried HDP Contact Tips on a line of 18 robots. Where previous contact tip usage for the operation was 216 per day — or about 1,500 tips per week — one HDP Contact Tip lasted an entire week on each cell, totaling 18 tips per week.
|The photos above show the difference in wear resistance among contact tips. The left photo of each contact tip type reflects zero minutes of arc-on time. The right photo of each illustrates 120 minutes of arc on time (20 minutes x 6 cycles) using high-speed pulsed waveform with an American Welding Society ER70S3 copper-coated solid wire (0.045-inch diameter). *|
In addition to the significant productivity gains the new contact tip design provides, there are other benefits for arc stability, productivity and operator safety.
Reduced frequency in contact tip changeover not only increases throughput while saving time and money due to downtime, it also reduces the risk of safety incidents, since every time an operator enters the weld cell it increases the risk of injury.
Also, each time someone touches the welding gun, there is the risk putting it out of alignment. The less frequently an operator must enter the cell, the less chance there is for human error that can disrupt tool center point that reduces part quality.
Frequently changing the contact tip can cover up other issues within the weld cell. When the contact tip is changed less often, other issues such as wire feeding problems, wire routing or a loose ground can come to the forefront. With standard contact tips, changing the tip out is often the first go-to fix when there is a problem in the weld cell — even if something else is the root cause. With a longer-lasting contact tip that is not changed as frequently, other issues that may not have been noticed before can now be fixed to improve the overall efficiency of the weld cell.
Return on investment
It’s important to consider total cost of ownership when evaluating contact tips and other consumables. The upfront cost of a contact tip is just one factor in total overall costs. A longer-lasting contact tip may be more expensive upfront, but it can provide significant payback in time and labor savings and reduced downtime.
Be sure to look at the big picture in terms of productivity and efficiency improvements for the entire operation.
In considering a switch in consumables, an operation should also be sure there is time to conduct a trial, which should always be part of changing the type of consumable or contact tip. The numbers will often speak for themselves when vetting the option and analyzing return on investment.
Improve productivity and efficiency
An operation may think the welding process is optimized, but that may not be the case if operators must frequently enter the weld cell to change the contact tip. As manufacturing operations look for ways to improve production efficiency and throughput in automated welding, choosing the right contact tip for the gun is one solution.
A contact tip designed to provide significantly longer tip life saves time and money in necessary changeover and reduces the frequency of people entering the weld cell. New contact tips on the market can last days in GMAW-P applications compared to standard copper tips that may only last a few hours.
*Other parameters: 450 ipm wire feed speed, 40-45 ipm travel speed, 90/10 mixed gas, 240-260 average amps on a Tregaskiss Robotic MIG Gun with a 22-degree neck.
As a premium quality brand of robotic MIG guns, consumables and peripherals, Tregaskiss has earned a reputation as an experienced, dependable partner to its customers in the automotive, fabrication, heavy equipment, agriculture, shipbuilding and repair, truck and trailer, and construction industries. Tregaskiss offers air-cooled robotic MIG guns, water-cooled robotic MIG guns, reamers, nozzle cleaning stations, anti-spatter liquid, wire cutters, anti-spatter sprayers, clutches, welding consumables, nozzles, MIG welding tips, welding torches, welding cables, and automatic welding torches.