Advanced Joining Techniques and Procedures

CRASH! BOOM! BANG! There it is: Another collision. Though we always hope that nobody was hurt, this collision means more work for your repair facility. But hold on a minute. This vehicle is a brand-new Interceptor RS50x. What is an Interceptor RS50x, you ask? It is a vehicle we created for this article, but imagine that it just showed up on a flatbed at your front door. It's a vehicle you haven't seen before and one that you now have to repair. Where do you begin? What is it made of? What are the repair procedures? Most importantly, where do you get the answers to these questions?

We have all heard of rivets, adhesives, primers, flange treatments and Squeeze Type Resistance Spot Welding (STRSW) welders that are now required to reattach many of the replacement components for today's collision damaged vehicles. In recent years, OEMs have been under extreme pressure to build vehicles that are not only more fuel efficient, but also safer. This why we have seen a massive use of advanced high strength steels such as Dual Phase, martensite/martensitic and boron alloyed steels. These steels are lighter due to the thinner-yet-stronger manufacturing process they go through, but you must keep in mind that these steels generally require replacement. They cannot be heated, pulled or repaired.

Today's collision repair professional needs a few important things to repair today's advanced construction vehicles: Information, equipment, training and, of course, pride in quality of workmanship. This article is going to look at the vast differences in repair procedures and the required equipment to restore a collision-damaged vehicle to pre-loss condition as per the manufacturer. Let's look at some of the differences between factory and collision repair assembly procedures.

STRSW

An electrical current is passed through two copper alloy tips that are pressed on the flange; the resistance of the steel causes heat to be generated and the metal to fuse together. The factory utilizes computer-controlled robotic resistance spot welders, while other robots position and hold the panels in place so the welders can spot-weld the panels together at predetermined locations. Some manufacturers utilize structural adhesive to bond the panels together and then STRSW the panels through the adhesive. This process is referred to as weld bonding. In the collision repair field, the joining technique may differ greatly from the original joining technique. In fact, some manufacturers allow resistance spot welding to be utilized, while others require GMA/MIG/MAG plug welds. Some manufacturers have specific criteria and allow for only specific spot welders to be used. Most OEMs require a one-to-one replacement spot weld ratio, but not in the same location as the original weld. Generally, when GMA/MIG/MAG plug welds are used, the replacement rule would be one-to-one in the same spot as the original weld. Some OEMs require a greater percentage of replacement welds — usually 10 to 30 percent more welds depending on the flange space. Some OEMs allow for weld bonding techniques to be duplicated with specific adhesives. Ford and Chrysler are two such automakers that allow for this. Other OEMs, such as BMW and Audi, do not allow weld bonding for replacement of their panels. Some manufacturers allow for STRSW to be duplicated in areas where the arms can reach (flange areas); in areas that are inaccessible, they will require specific structural adhesive and structural rivets to be used. It should be noted that single-sided STRSW is not recommended by any OEM!

Mercedes Benz requires STRSW in flange areas with structural rivets and adhesives in inaccessible areas, or areas where dissimilar metals are attached (steel to aluminum). GM requires structural rivets and adhesives for the front uni-rail replacement on some of their vehicles, due to the laminated steel firewall/dash panel. Other automakers require structural rivets and adhesives for replacement of the B-Pillar reinforcement due to the material used. Mercedes Benz in particular requires this procedure for their USIBOR B-Pillar (boron). Other OEMs (for example, Audi, for their martensitic steel B-Pillar) allow the B-Pillar to be plug welded and STRSW using very specific equipment.

Laser Welds

Some OEMs utilize a robotic laser welder during the vehicle assembly process. Generally, laser welds are utilized in the roof panel to the uni-side mating joint. Audi, VW, Porsche, Bentley and Volvo are some manufacturers that utilize this process. When replacing a laser-welded panel, the replacement procedure usually requires the complete removal of the laser weld and the STRSW in the glass opening flanges. The replacement procedure generally requires specific structural adhesives in the areas where the laser welds were originally located and STRSW in the glass opening flanges.

MIG Brazing

Some manufacturers utilize MIG brazing in areas where the panel joint must flex, due to the torsional movement of the vehicle. Brazing is not a fusion weld; it is actually similar to an adhesive bond. Generally, in the collision repair industry, MIG-brazed areas are replaced with MIG brazing techniques or adhesive bonding procedures. MIG brazing is relatively easy to learn and master with a few lessons, the proper equipment and — as always — practice, practice and more practice. Once you think you've mastered it…practice some more!

So with all the different types of steels, joining and OEM-specific repair and replacement procedures, you may be asking yourself, "How can I keep up?" First, you have to want to keep up. As we all know, "keeping up" basically means "change." We are all guilty of becoming complacent at times; after all, changing our way of thinking or doing things can be difficult. We all think we know what we are doing, and we also think we have a better way of doing it.

In today's industry, everything is changing. We are here to help guide you through the obstacles you will inevitably encounter. Once you realize that "you don't know what you don't know," you'll begin to understand that proper information is the key to today's repair procedures. The answer cannot come from the insurance company, insurance adjuster, repair technician or even your own opinion. All the information you need is on the OEM's website, or an informational website like www.ALLDATACOLLISION.com. You need to have the access to the information directly from the OEM. This repair information will let you know where to section, what needs replacement, the joining methods, the substrate construction and the recommended or required equipment. After reading the OEM procedures, you will then need to invest in the proper equipment, if you do not already have it. Training on that particular equipment will also be necessary to ensure the longevity and the proper usage of the equipment. You must make sure that the estimators, technicians and insurance adjusters understand what is required by the OEM, the necessary equipment and the materials to repair the vehicle properly and ensure it will react as intended by the OEM during a subsequent collision event. Not following OEM-required repair procedures — or repairing a vehicle that you are not certified or equipped to repair — may expose you to liability.

Hopefully, this article has brought to your attention the importance of understanding advanced joining methods on today's vehicles, the equipment required and, of course, where to find the correct repair information to restore the vehicle to its pre-loss condition as per OEM procedures. One last question: Do you feel more prepared to answer the questions we asked about the make-believe Interceptor RS50x, now that you have read this article?

Feel free to contact us if you have any questions that we could help with.

Larry Montanez, CDA is a former I-CAR Instructor, and is co-owner of P&L Consultants with Peter Pratti Jr. P&L Consultants works with collision repair shops on estimating, production and proper repair procedures. P&L conducts repair workshops on MIG & Resistance Welding, Measuring for Estimating and Advanced Estimating Skills. P&L also conducts investigations for insurers and repair shops for improper repairs, collision reparability and estimating issues. P&L can be reached by contacting Larry at Office (718) 891–4018; Cell (917) 860–3588; Fax (718) 646–2733; E-mail larrygoju@aol.com.

Jeff Lange, PE, is president of Lange Technical Services, Ltd. of Deer Park, N.Y. Jeff is a Licensed New York State Professional Engineer who specializes in investigating vehicle and component failures. Lange Technical Services, Ltd. is an investigative engineering firm performing forensic vehicle examinations and analysis for accident reconstruction, products liability and insurance issues. Jeff can be reached at (631) 667-6128 or by e-mail at Jeff.Lange@LangeTech.net. For more information on Lange Technical Services, please visit www.langetech.net.