Today’s automobile consists of an aluminum alloy or carbon steel chassis and frame covered by plastic material.It has been found over the years that an automobile made entirely of metal is not only heavier but also subject to stone chips, corrosion, dents and other problems.The choice of plastics for the exterior design has not only allowed advanced design techniques and lowered production costs, but has also produced safer and more energy efficient vehicles.
The continued use of plastics has resulted in a lighter vehicle as it weighs approximately 50 percent less than steel. This has led to advancement in gas mileage and fewer emissions, while retaining safety features. New techniques also allow manufacturers to recycle and re-use scrap plastics, which has helped the environment. Regardless of the type, model or style of an automobile, it still is subject to the errors of human drivers.
This means there are countless wrecks, which result in minor damages or a vehicle that is beyond repair. Many people do not realize that a car’s heavy plastic cover can break and often causing fender or bumper damage. This starts with an examination of the damage and an estimate of the repairs. For those who do not have insurance this can be a catastrophic amount.
This plastic is divided into four types:
Poly propylene– used on Dirt Bike Fenders and RV Water Tanks and not suggested for painting or repairing.
• SMC– used on new Corvettes and other vehicles has white powder and resembles fiberglass.
• TPO-feels like wax and melts with high-speed grinders.
• Thermo-Set (Rigid or Flexible)- easy to repair, does not melt when used with high-speed grinders.
Of the four different types of plastic,
TPO is the most difficult to repair.
While this type of plastic is repairable, it is so difficult to handle that many shops simply throw it away. SMC is recommended by the ACA division of the American Composites Manufacturers Association. Among other things, they report substantial weight reduction, reduced tooling cost, damage resistance in body panels, corrosion resistance, improved noise properties and design flexibility.
Automobiles that have a significant amount of SMC in molded parts include Dodge Viper, Ford Edge, Pontiac Solstice, Ford Escape, Chevrolet Corvette, G Hummer-2 and Cadillac XLR. In 2007, Nissan and Meridian created a trunk divider panel, with extra reinforcement of high tensile strength SMC, in its Sentra sedan. New in the field, General Motors Corporation, together with Decoma International Inc.’s Polyrim Division and Dow Chemical, has developed a new plastic called a RRIM (reinforced reaction injection molding).
The first commercial application has been new sport side panels on Silverado/Sierra pickups. In addition to claiming this is a stronger plastic, they report that it has reduced material cost by 4% and that 53% less fasteners are required. Automobiles have crush zones, especially designed to absorb force during a crash. These zones cause the automobile to collapse in a prearranged way. Repairs can be made on certain parts of a damaged automobile while others require replacement with a new part.
Complete replacement of a part is required:
• Cost of repair is more than replacement
• If damage is located in a crush zone
• If metal is tightly folded or kinked
• If damage is close to stress areas (i.e.
Once in the shop, a technician will disassemble the vehicle, look for any additional damage. Additional damage that requires new parts or extra work will change the original estimate.Typically, damage occurs in the rear, frontal, side and top of a vehicle.The various tools used to make structural repairs depend on the location of the damages and the work required.
These tools include such things as a tram gauge, plasma cutter, spot-weld cutter, reciprocating saw, air chisel and many others. However, many of the measuring tools are becoming obsolete with the introduction of computerized measuring.
A number of different computerized measuring tools are available. One sophisticated model has a laser scanner and a computerized database that shows the extent of structural damages, monitors repairs and displays overhead diagrams, which display measurements of the damage.