Last year, I was hired by Holmes Body Shop to set up training and quality control procedures for the company. About a week into the job, I inspected a vehicle that had new front end structural parts installed with plug welds. The plug welds visibly ranged from good to poor (I couldn’t determine their structural integrity). I explained to the tech that his welds needed improving and suggested that he redo the welds on the vehicle. I also observed his welding techniques while performing some practice plug welds and suggested that he change his gun angle and increase the “stick out.”
I discussed the situation with Steve Morris, vice president of operations, and Wade Sill, center manager, and both agreed that the tech needed to redo the welds. So he did.
I then recommended to Steve and owner Tom Holmes that all the technicians in the company take the I-CAR steel welding qualification test. The test consists of performing six welds — a butt weld with backer, a fillet weld, a plug weld in the vertical position and then the same three welds in an overhead position. The completed welds then are sent to a testing company, where they first must pass the visual test. If they pass, then they’re destructively tested. If all six welds pass both tests, the technician is given a certificate of completion, which is good for five years. If any of the welds fail, the technician can retake the test, redoing only the welds that failed, but the retest must be concluded within six months of test results.
As I suggested, Steve made arrangements to send all of Holmes’ technicians to the test; 30 techs took it. They were offered a new automatic darkening welding helmet if they passed the test on the first try.
Twelve passed on the first attempt.
Fourteen techs failed one weld (I might add that none of the techs took the I-CAR practice welding class, but if they had, the pass rate would have been substantially higher), three failed two welds and one failed three welds (he’s no longer with the company).
To date, 15 of the remaining 17 techs have retaken the test and passed. The other two have been practicing and are scheduled to take the exam.
Tom and Steve are both pleased with the test results, and all future employees will have to take and pass the test as part of their employment requirements. I might add that the tech who passed all his welds on the first try was the same tech whose poor welds started the testing as a company policy. In addition, this same tech tutored one of his helpers, who passed on his first try. This tech also arranged with me to purchase two new welders (one for him and the other for his helper) through a welding purchase program that Tom has implemented at the company. Any tech who passes the exam receives a loan from Tom to purchase his own machine. The money is then paid back through payroll deduction.
Marco Auto Body is another success story. I approached owner Marco Maimone about participating in the welding qualification test. Marco (below) set up a testing date with me and had seven techs sign up. He also signed up, even though he hasn’t welded on a car since the turn of the century (and not the 20th — the 19th century). It took Marco nearly a full day of practice, but he managed to get through the test. He told me that everyone was extremely nervous, but that every one of them felt their welding skills had greatly improved due to the coaching in the pretest. And every one of them passed the pretest that was given that day.
Because, during the process, I noticed that many of the techs angled the gun improperly and misunderstood what the shielding gas was for, let’s quickly review the MIG welding process.
First, most managers, estimators and shop owners have no clue about MIG welding, yet it’s the method of choice for welding on today’s cars. The technical name for MIG welding is metal inert gas welding. The diagram below represents a typical MIG welding gun and process. The things that are of interest to us non-technical people would be the shielding gas, wire size, gun angle and stick out.
Stick out is distance from the end of the contact tip to the welding surface. The recommended length ranges from a 1/4 inch to 3/8ths of an inch. Shorter stick-out lengths cause the electrode wire to fuse to the tip, which in turn causes the wire to stop feeding the weld. Another problem with a short stick out is that the techn cannot see the weld properly (it’s hidden by the nozzle).
The proper wire size for most collision applications is .023 wire, especially with 110-volt
welders. The .030 wire can be used, but it works better with heavier gauge steel and it’s the wire of choice with 220-volt machines. The wire should not be flux coated.
The shielding gas used is a mixture of 75% argon and 25% carbon dioxide. The welding gas isn’t needed for the welding process, but it is necessary to keep nitrogen and oxygen out of the weld site. Why? Because nitrogen and oxygen can cause fusion defects and porosity. Improper gun angle (70 degrees or less to the welding surface) will allow the gas to blow away from the weld and oxygen and nitrogen to contact the weld during the welding process.
The proper gun angle is 10 degrees from perpendicular to the welding surface, as shown below from www.hobartwelders.com/techtips.
At a recent I-CAR welding pretest, I had eight technicians perform two plug welds, prior to beginning the pretest part of the program, and asked them to select their best one. Look at the sample of one of the welds.
How would you judge this weld? It would fail my visual because it’s too small in diameter.
The weld also failed the destructive test.
The plug weld, when pulled apart, left a hole in the top coupon, which indicates there was no weld penetration to the top coupon. To pass the destructive test, the plug weld needs to remove metal from the bottom piece of sheet metal (minimum tear out is 5mm hole).
The weld above right also failed the destructive test because there was no penetration to the bottom coupon, even though the weld passed the visual inspection for size (weld also filled the 8mm hole completely).
Seven of the eight techs would have failed the I-CAR qualification test if their initial plug welds had been submitted. I might add that all of the eight techs then practiced for more than four hours, and every one of them was able to submit eight plug welds for testing that I felt would pass both the visual and the destructive test (the welds go to an independent test).
Another fact that should be noted is that General Motors, Ford, Toyota, Lexus, Volvo, Chrysler and Jaguar only recognize I-CAR’s qualification test for their collision certification programs. You can find the OEM requirements at www.i-car.com (center of the home page).
But why should you send your techs to training, you ask? What do you get out of it?
For starters, it helps quality shops distinguish themselves from the rest of the industry. It’s also a great marketing tool. More importantly, since most of the welds I’ve inspected would fail a destructive test, think about your shop’s liability factor. Most shop owners who send their techs to training want to sleep better at night.
Wouldn’t you like to sleep better too?
Contributing Editor Toby Chess has more than 30 years of industry experience. Chess is an ASE Master Certified Technician, an Accredited Automotive Manager, an I-CAR instructor, the Los Angeles I-CAR Chairman and a technical presenter for CIC. He can be reached at [email protected].
If your company has achieved 100% passing of the I-CAR welding qualification test, e-mail me at [email protected]. Please include I-CAR Welding as the subject.
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