How It Works: Collision Repair
New materials and designs used in today’s cars mean fixing them after a crash is more complex than ever before
Just as cars have become more complex over the years, so have their repairs, and that includes when they get hit. At one time, body shops mostly straightened the metal and fixed the paint. Today, they deal with high-tech materials and technologies that can require very specialized repairs.
“The change in repairing the vehicle is dramatic,” says Dean Fisher, chief operating officer of CARSTAR Auto Body Repair. “Everything used to be built with mild steel. Now we have high-strength steel, double-strength high-strength steel, aluminum, and by 2020 we’ll see carbon fibre at a level we’re not used to seeing.”
Collison repairs start with an estimate, and today they’re usually done with the aid of computer programs that provide detailed information on what parts are needed, procedures for the repair, and the cost of parts and labour. Some programs can cross-reference dealer and recycler inventories, and directly place the order for the required parts. The body shop has to determine the full extent of the damage, especially since some of it can be hidden.
From there, the insurance company and the customer get involved to determine if it’s economically viable to repair the vehicle and, if so, to authorize the work. Determining what parts to use – new from the automaker, from an aftermarket manufacturer, or used – depends on a few factors. “There’s the dilemma,” Fisher says, adding that various insurance companies may prioritize price, or factory-authorized equipment, or quality and customer satisfaction to make a decision.
If the damage is severe enough, repairs begin with the basic structure. Almost all cars and SUVs are unibody, a blend of body and chassis, while heavier-duty vehicles like pickup trucks have a separate body and frame. Everything needs to be brought back in line with the manufacturer’s original measurements and specifications. In some cases, the vehicle is secured on a platform, known as a bench, and clamps or chains are used to pull it straight.
Not everything can be repaired this way, and sometimes sections must be cut out and replaced, especially if the metal has been kinked or cracked. This is where the body shop has to know precisely how the vehicle was constructed in order to maintain its crumple zones correctly.
These zones are an important safety feature. The passenger cabin is a strong, rigid cage, while the vehicle’s exterior is designed to progressively crumple around it in a crash. This dissipates the crash energy so it isn’t transferred to the occupants. To create that gradual creasing, automakers use components made from various strengths of steel.
Not only must these be replaced with the same grade, but how they’re put together can make a difference. “If you’re supposed to have twenty welds in the wheel housing, but you put in thirty, you’ve made it stronger and changed the strength of that panel in a crash,” Fisher says. A stronger panel may seem safer, but it will now change the way the vehicle crumples, or even what it takes to set off the airbags.
Some components are bonded or riveted, and repairers must follow the manufacturer’s specifications for the type of adhesive and how the rivets are put in.
Heat is often used to repair metal, but it must be used cautiously. If metal gets too hot, it can change the molecular structure, which in turn can make it brittle. “If there’s magnesium in a vehicle, you can’t repair it, because it changes the strength as you pound it or heat it,” Fisher says. Repairers often use heat crayons to draw a line on the metal. The crayon melts at a specific temperature and warns if the metal’s getting overheated.
The exterior gets just as much attention, because some body panels are structural. Some dents can be repaired, but metal that’s been kinked or stretched too far must be replaced. From here, the metal is finished and primed, the vehicle is painted, and then it’s reassembled and cleaned.
Automakers are continually adding more lightweight materials in vehicles, resulting in more complicated repairs and, often, more replacement. A few composite materials can be repaired, but just as with metal, it can’t be made stronger than it’s supposed to be.
Safety technologies can also pose headaches for body shops. Some warning systems use sensors in the bumpers or body sides, and these must be precisely aligned after a panel is repaired. A mirror replacement becomes trickier when it contains a camera for the monitoring system. Vehicles that can automatically brake to avoid a collision sometimes have that sensor located behind a thinner section of the front fascia, and if it’s painted too many times, the sensor won’t be able to “see” through it. Some manufacturers provide the replacement fascia already painted, Fisher says, to help avoid the issue.
All of this means body shops need more training, more information, and more high-tech tools, some of them manufacturer-specific, to repair damage properly. It’s no longer enough just to fix a dent; body shops must analyze, diagnose, and scan vehicles, just as repair shops do, to be sure everything’s working before they’re handed back to their owners.
Source: https://bit.ly/3agiPIx
