There are many similarities between heavy-duty truck and passenger autobody composite repair and bonding procedures, but the key is understanding that the size of the repairs and panels are considerably larger and require different space considerations.
Repairs to heavy-duty composite vehicles follow the same Standard Operating Procedures (SOPs) as the automotive SOPs, but the biggest difference is larger, thicker panels.
Technicians need to keep this in mind when choosing which adhesive to use for the repair. The adhesive must meet original equipment manufacturer (OEM) specifications or be OEM-approved. Repairers also need to be mindful that it is best to select a product with the longest work-time possible because of the larger surface area. The option of a longer work time is always better than not enough time and botching a job.
It may not be feasible to complete a heavy-duty composite repair off a vehicle because of space constraints. Accessing the rear side of the panels for a structural repair can be challenging because many heavy-duty truck hoods are constructed without any backside access from the outer panels to perform reinforcing operations.
In this case, either the panel can be disassembled, repairs made and reassembled, or panels are replaced because although repairable, it isn't the most logical choice since a replacement would be quicker.
Traditional methods for fiberglass repair such as using fiberglass cloth or mat, resin and hardener can be messy and may require multiple applications.
Making repairs with adhesives is relatively simple, but it is important that during the process, technicians replace the fiber for both aesthetics and structural integrity of the vehicle.
Using a generous amount of fiberglass repair cloth is essential to eliminate read-through and to ensure that there isn’t a different coefficient of expansion in the area surrounding the repair, which may result in a “halo effect” or “bullseyes.
Technicians also need to understand the importance of repairing the damaged part with minimal additional weight and the need for quick turnaround time when making heavy-duty composite repairs.