When evaluating the cost of your welding operation, it is important to consider the low-cost items that stack up over time; like your consumables, and more specifically, your contact tips.
One bad habit I see a lot is disposing of a contact tip before the end of its life. For instance, changing out a contact tip at every shift change, regardless of the condition of the contact tip.
To get the most out of your production budget, you need to make use of the entire lifespan of the contact tip. With testing, you can figure out which contact tip provides the longest lifespan possible.
Both lab testing and production testing are great ways to ensure that you are getting the best value for the cost. But where do you get started?
Contact Tip Testing Methods and Mistakes
First, let’s talk about how not to test your contact tips. A common mistake made when testing is a lack of communication and supervision of the tests. For example, you can’t run one contact tip continuously with multiple operators. One of them might not know a test is running and replace the tip, ruining that data set.
I have run multiple contact tip tests in my time working for Automotive Suppliers. When we would draw out the methodology, one of the golden rules we had was only running the consumable test on first shift where we had engineering supervision. This keeps the logging of information reliable and consistent, and ensures a true test result. Even if this method may drag a testing process out for a longer period, it will result in the most objective outcome when comparing different contact tip for your welding process.
If you do run a contact tip test over multiple shifts, one common mistake made is trying to run the same tip across each of those shifts. To get a truer comparison, I recommend each operator having his or her own contact tip to use. When they leave their shift for the day, the operator should take that tip with them. If it’s still good, keep running with it. When it wears out, log that longevity and the other data you are recording.
You also need to be sure that station you are using for tests has no room for error. This means replacing all other wear items before testing (wire liners, drive rolls, etc.) and checking that your weld parameters match from test to test.
Make sure that you have a consistent and controllable environment, so that you can produce consistent data.
That doesn’t mean that you need to perform all of the tests in a lab setting, though.
Should You Test Contact Tips in a Lab Environment?
You should still use the lab, but not for your main group of tests.
The lab should be used to find a baseline, and narrow down your tip options. Make sure that your lab conditions are as close to the production environment as possible. Part of ensuring true apples to apples comparison is controlling variables such as:
- Wire travel distance
- Wire tension
- Weld parameters
- Wire feed speed
- Torch setups and
- Welding jobs
These all should be the same from contact tip to contact tip as you whittle down to the Production Test.
Gather your ‘contestants’ for the test. Find a few different tip options from different companies, I usually use five or six different contact tips. Run the first tip option until it fails. Then reset the test and run the next tip until it fails.
Do this with all contact tips you are considering and compare the results of longevity and weld quality, head-to-head, to find your “champion”. This contact tip will be the one you use for your production testing; against the contact tip you are currently using.
Testing Contact Tips in Production
After finding your “champion”, move from the lab to a production environment. Moving to a real production environment is important to gathering real-world data. A lab setting is easily controlled and provides accurate results, but different factors exist in a production setting that don’t exist in a lab setting.
A controlled environment can only take the Contact Tip testing so far. The production line is where all the real world factors that matter will put more stress on the contact tip and prove it’s meddle against your current choice.
These can include factors such as:
- Wire travel distance
- Atmospheric conditions (oil, moisture, dirt, etc.)
- Continuous heat output
- Increased spatter from the process
Find the robot cell that you will be testing. It’s more convenient to use two robots at once for your testing, one with the currently used tip, and the other with the competitor tip. The biggest upside to using this testing method is you cut your test time in half. However, you open up for many uncontrolled variables that can taint the test and get you the incorrect result.
To get a true comparison, I recommend using the same robot for all tests. This tests for true consistency. There could be slight variances between robots, torch components, power supply settings, etc., so only using one makes controlling variables (wire travel distance, wire tension, weld parameters, torch setups, and jobs) much more reliable.
Additionally, you won’t have to change out as many wear parts when conducting your tests.
Start doing a one-to-one comparison. I have found that to get the best statistical analysis, with plenty of data to compare, a set of 30 tests for 30 tips is optimal.
While testing, it is crucial that you record arc-on time as well as any burnbacks, instances of micro-arcing, failures, or malfunctions that may have happened.
A good way to get accurate arc-on times is to put an arc-on timer in the PLC of your robot.
The main metric to focus on is longevity.
How Much Arc-on Time Can the Contact Tip Take Before Replacement?
This directly relates to cost. You may be paying less per tip with ‘Company A’, but paying more in the long run because they don’t last as long as the tips from ‘Company B’.
You need to weigh your test results with the cost of the tip to see if you are getting the best possible deal for your production.
Overall, testing contact tips is a straightforward that is heavily reliant on consistency in conditions and data collection.
Stay disciplined in your methodology.
And stress keeping the number of personnel involved to a minimum to avoid irregularities.
Without a proper data set, making a decision to change your current welding process might end up costing you more in consumables long term.