Editor’s note: This is the second part of a two-part series on understanding plastic and composite repair with adhesives. See Part One to learn how to make successful plastic repairs with adhesives, plus why shop management should carefully consider the cost of equipment and necessary training before investing in the next “cool tool” for the shop.
As automakers are expanding their use of composite plastics such as carbon fiber, fiberglass and sheet-molded compound (SMC) in vehicle construction, there is also the need for body technicians to understand their repair options and how to do them properly.
Tighter government regulations on emissions are driving demand for automakers to use carbon fiber to build high-strength, lighter-weight vehicles that can meet U.S. Corporate Average Fuel Economy (CAFÉ) standards and European Union (EU) carbon dioxide gas emissions requirements. There is also a rising demand for carbon fiber-reinforced plastics (CFRP) in luxury cars, race cars and other high-performance cars.
“Vehicles’ structures have regularly changed, but it didn’t become overly significant to the collision repair industry until about the 1990s,” points out Kevin Creegan, Sales Manager for LORD Fusor Aftermarket Repair Adhesives in the US and Canada. “This is when collision repairers began to deal with repairing vehicles built with unique structural elements and different materials such as high-strength steel (HSS), ultra-high-strength steel (UHSS), composites and other mixed materials.”
|Cover the damaged area in the composite panel with masking tape. This protects the damaged area from absorbing the plastic and rubber cleaner and eliminates wicking of the cleaner through the fibers into the composite.|
Carbon fiber in the global automotive composites market is forecasted to grow at a compound annual growth rate (CAGR) — a measure of growth throughout multiple time periods – of 10.4 percent from 2016 to 2021, says global research company Lucintel in its March 2017 report, “Growth Opportunities for Carbon Fiber in the Global Automotive Composites Market.”
With the growth of light weighting, many of the major vehicle manufacturers, including BMW, Mercedes, Toyota, FCA, Ford and General Motors (GM), have put focus on incorporating carbon fiber into mass production vehicles. Recent news reports indicate that the next generation of General Motors pickups will be made mixed material, with a high-strength steel cab safety cage and aluminum doors. Higher-end versions of the GMC Sierra and Chevrolet Silverado trucks may feature carbon fiber.
Creating a high-strength bond
This growing use of composites by original equipment manufacturers (OEMs) also means both seasoned and new technicians will need to receive training to understand proper repair methods – and options – for structural and cosmetic repairs.
When vehicles manufactured with composites were first introduced, the mindset was typically to replace the parts, Creegan says, as the repair capability wasn’t yet developed. Initial attempts with resins and fiberglass matting would either completely fail or read through was common. Technicians would replace large component pieces to deal with small, locally damaged areas. “This just isn’t efficient and is too costly, especially for high-volume vehicles,” Creegan points out. “It’s easier to fix a small, damaged area on panels and hoods than replacing the whole part.”
|The reinforcing patch on the back side of the repair can be made with either a matching piece of composite material or formed from fiberglass cloth.|
Now, repair adhesives specifically formulated for composites are providing technicians with an economical, alternative solution to simply replacing these parts or using welds and rivets. The introduction of new products and procedures is now allowing for robust repair.
“The bond created when using repair adhesives on composite substrates is as strong – if not stronger – than rivets and welds,” Creegan points out. “Using repair adhesives also offers advantages such as lightweighting, bonding dissimilar materials, aesthetics and reducing noise vibration and harshness (NVH).”