How to Execute a Proper Weld

Jan. 4, 2019
Industry experts share the actions needed to gain a weld that will stand up to the test of time and return the vehicle back to pre-accident condition.

Technicians may have 10–20 years of collision repair experience, but that doesn’t necessarily mean they’ve been properly trained to weld on newer vehicles.

“Only about 75 percent of the technicians coming to tests take it seriously and the other 25 percent come and complain,” says John Helterbrand, department chair, automotive collision repair and high performance racing technology at Ranken Technical College in St. Louis.

In addition to his role as department chair, Helterbrand has been an I-CAR instructor for the last 13 years.

Mike Croker, global repair and training product manager, collision for Chief Automotive Technologies, has been in the industry for more than 18 years and he says the proper welding technique takes continuous training.

If technicians don’t follow the proper welding techniques or wear the proper equipment, the weld might not hold up and create even more damage on the repaired vehicle.

On top of the weld causing more damage, respiratory effects (specifically impaired lung function and fibrosis), have been found in workers who have been exposed to aluminum dust or fumes, according to the U.S. Department of Health and Human Services.  

Croker has been around enough fumes in his career that he says his lungs have started to deteriorate. When he gets sick, he has had to be admitted to the hospital and can be out for weeks at a time.

“I’d rather know about the tools and pay for safety equipment than go through the cost of all the hospital bills,” he says.

Croker and Heckerbrand outline the actions a technician needs to follow to pass a weld test and maximize the investment in welding training (sometimes as much as $1,100 per technician).

Action No. 1: Schedule for the certification test well in advance.

Technicians need to take a welding certification test through I-CAR every five years. For some certification programs through OEMs, the testing occurs every six months.

Helterbrand says shops don’t put enough priority on when and where they will schedule the I-CAR certification test. He says in many cases the technicians are simply not prepared for it.

He emphasizes that tests shouldn’t be scheduled on a weekend because a technician comes in and often isn’t mentally prepared to work on a day like Saturday.

Before scheduling, the owner and technician need to take time, well in advance, and look online at the free welding qualification and materials information provided by I-CAR. The types of materials that will be used in the test depend on whether the test is done by a manufacturer or by I-CAR.

Most importantly, Helterbrand recommends a shop owner block out a time for the test that is separate from the day’s production schedule. He says the technician needs an environment in which the equipment has been checked and is ready to be used, and the technician can solely focus on the test.

Action No. 2: Put on proper safety gear.

A technician needs to wear a welding jacket and welding gloves, Croker says. A better and safer helmet will have a darkening shade on it. Closed-toe boots are a must. The gear protects a worker from the light and heat generated by welding.

“It surprises me how often technicians do not think about ventilating the fumes they are inhaling,” Croker says. “Proper ventilation systems are not that expensive and only cost about $3,500, give or take.”

Only a very low percent of the shops Croker has seen and worked with use some type of ventilation system for the fumes.

Croker says he personally prefers a welding helmet with an attached fume extractor. Fume extractors are critical because while there might be standards out there, some chemicals and fumes, like the ones used in manufacturing, are so severe they can send you to the hospital.

Action No. 3: Make sure the shop’s equipment is working.

Each manufacturer will have its own equipment requirements. Welders usually run off on a power system of 220v.

Croker learned 15 years ago, when he took his first I-CAR weld test, that an old machine can slow down a technician. With old equipment, it takes roughly many more hours to complete a welding certification like upwards of six but with a new machine, it can be completed considerably faster and easier within a couple hours.

Helterbrand says if a shop schedules a test weld, it needs to adequately prepare for the testing day. He says shops often run out of welding gas needed to complete the weld and forget extra tips or nozzles to use the welder.

“Most of the technicians have old equipment with no manuals available and assume they know how the equipment works,” Helterbrand says.

Don’t buy a new welder right before the test, Croker and Helterbrand say. Often, techs buy new equipment and then go take the test. The weld test could then take them hours and hours to complete.

Action No. 4: Do a test weld before actually doing the proper weld.

Doing a test weld on the same type of material  the welder will be performing the job on, can prevent the weld from failing on a customer’s vehicle.

During the weld test, Helterbrand says that instructors will test the weld by methods such as bending the metal back and forth or twisting. The instructor looks for a patch or fail in the actual weld.

Simply make sure the welding process is going to hold up by taking the smaller piece of metal once it’s welded, put it in a vice grip and try to tear it apart, Croker says. This testing of the weld is usually referred to as a destructive test.

“No one can tell if the weld is going to work by simply looking at it,” he says.

Action No. 5: Use the proper technique for the metal.

Aluminum equipment is also set up differently and a pulse-welder or a double-pulse welder is used. The wire size is different. Argon gas is used instead of an argon gas mix used in steel welding.

Steel melts at a higher level than aluminum. The tools used for steel cannot touch aluminum and vice versa. If the metals were to touch, it could cause contamination on the metal.

With aluminum, someone is typically pushing and with steel, someone is typically pulling.

In steel welding, the wire is more robust than aluminum. In a MIG welder, the wire can be pushed by the rotating feed roller all the way to the end without collapsing in on itself.

Croker says aluminum wire can easily jam the gun when it is loaded. Since it is a softer wire, the technician needs to use a push-pull gun in which a specific welder can push the wire from the feeder while a pulling feeder is in the gun itself, maintaining constant tension and preventing the wire from getting tangled.It also allows for the welder torch length to be much longer, making it easier to work around a vehicle.

 It’s harder to push aluminum, so a welding gun that has more length is ideal. For instance, the technician does not need a machine close to the car if he or she has a welding torch three times the standard length of a typical welder.

In addition to the wire differences, aluminum conducts heat more rapidly than steel, shrinks when it is re-solidified after being welded and has twice the thermal expansion of steel.

Action No. 6: Test the weld visually.

While you can’t do a destructive test on a car once the weld is done, there are other options for a final work check. One solution is simply having a visual test of it and making sure it meets welding standards.

 A more accurate test is to use a dye penetrant and inspection kit that includes a spray, Croker says. The welder can spray one coat onto the car, wait for it to dry and spray a second coat. If  there are cracks that are smaller than the eye can see, the second coat will react to them and show it to the naked eye.