Today’s vehicles are made with many different types of fuel-saving materials like lightweight alloys and plastics. It is important for an auto body shop to be aware of the different materials and techniques used for repairing them.
Auto body shops and collision repair services refer to manuals for instructions repairing bumpers. The different material types require various finish materials, removal and installation procedures.
When a plastic bumper is cracked or has a small hole it can be repaired to look as good as new. Replacing the bumper is wasteful and it creates unnecessary debris for our landfills. A good, eco-friendly auto body shop will only recommend replacing the bumper if the damage is severe enough that repair time would be considered unreasonable and quality of results would be unsatisfactory.
The cost of repairing small abrasions, cracks and holes in plastic bumpers is often much cheaper than replacing the part. Of course, many collision repair technicians would rather replace the part and charge a fee for their labor plus mark-up on the price of the part because they lack in cosmetic repair skills and it is easier to warranty the work.
Working with Plastics
The first step to repairing plastic bumpers is to identify the material in order to choose the method of repair. Auto body shops use ISO codes on the parts to identify the various families of plastics. They cross-reference the codes with charts from the suppliers or by accessing reference materials on the internet.
It is important that the collision repair technician determine the type of plastic they are working with so they know the proper welding procedure to use to avoid damage to the part.
Some plastics can be welded with an airless welder or hot-air welder; others require a hot glue type of procedure. Tests must be performed and welding procedures have to be done correctly to avoid adhesion failure. Some bumpers will melt with a slight color change and they will remain tacky in the area where they have melted.
The bumper repair technician must identify the type of plastic they are working with in order to be successful with adhesive repairs. Failure to properly identify the plastic results in adhesion-related problems.
Some repair materials are based on flexible and rigid plastics. Using the wrong material can cause cracking when the part is flexed or it may not provide the correct strength for the repair area.
Cleaning and Prep
Proper cleaning and prep is critical for proper adhesion and finish. Whether the technician is repairing or replacing the bumper, the part will need to be cleaned. The bumper being repaired is likely to be dirty from the road; the new replacement part can have contamination on it from the manufacturing process.
Auto body repair professionals should use a low-VOC surface cleaner or a special plastics parts cleaner to help prevent solvents from going too deep into the plastic. If solvents are too harsh, they go deep into the plastic and cause adhesion problems after repairs are done.
This is an overview of the process of working with plastics. Time is money in the auto body industry; therefore, many collision repair technicians choose to replace rather than repair plastic bumpers and other parts.
Technology allows us to repair many items that are often replaced. As resources become scarce and landfills become over-full, we really should consider repairing rather than replacing when possible.