What to know about heavy-duty composite repair

Imagine, for example, a tractor-trailer driving down the road but focus only on the tractor or cab. The hood, fenders, roof, various ground effects, spoiler fairings, and on the tractor are typically all made of composites – and are usually very large parts.  

If a truck sustains damage to the right front and it affects the hood and front fender, it may be possible to repair these parts right on the vehicle instead of removing them. If the parts are removed, they would need to be placed on a bench or parts stand.

Repairing this way isn’t necessarily incorrect, but it is easier to access the truck when everything is all together. The reason is two-fold. Not only are the parts very large – making it easier to directly patch the truck instead of taking it off of its chassis – but they can be difficult to handle, especially if a single technician is handling the repair job.

Making repair material choices

The repair process itself to a heavy-duty composite vehicle follows the same Standard Operating Procedures (SOPs) as the automotive SOPs, with the biggest difference being the larger, thicker panels.

Technicians should keep this in mind when choosing which adhesive to use for the repair. Not only should technicians ensure the repair adhesive meets original equipment manufacturer (OEM) specifications or are OEM-approved, but it’s also best to select a product with the longest work-time possible – more work time is always better than not enough and botching a job.

The fastest-acting adhesives will most likely be unsuitable because of the large surface area involved with the repair. Shops and technicians are all different and where some may use the slowest products everywhere and then apply some heat to accelerate, others use a full range of products adjusting for size of the repair and the current shop conditions (temperature). Hotter environments require slower products and vice versa.

Making the repairs with adhesives is relatively simple, but it is important to understand the product being used and to carefully follow instructions to guarantee the best results. It’s more than just pumping in a product to glue parts together. If the repair procedure is done properly the first time, the repair will last for the life of the vehicle.

During the actual repair process, it is important to replace the fiber and to use it with adhesive for both aesthetics and structural integrity of the vehicle. Using a generous amount of fiberglass repair cloth in a heavy-duty composite repair is critical 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.”

Sharp edges from failure to taper, temperature changes, lack of full heat cure to eliminate shrinkage after painting, and insufficient fiberglass cloth (so the repair acts like sheet-molded compound) during the repair process can all contribute to read-through.

Using adequate fiber is essential, but technicians also need to understand why it’s so important to repair the damaged part with minimal additional weight. The addition of a couple extra pounds might seem insignificant, but if it’s done in enough sections of repair across the vehicle, even this slight added weight can result in poor mileage or impact overall mileage efficiency on an over-the-road, heavy-duty truck or trailer. It’s crucial to reiterate the necessity of reapplying and making certain fiber and adhesive are used in conjunction with the repair – not just simply the use of adhesive.

The ongoing question: Repair or replace?

When vehicles manufactured with composites were first introduced, the typical mentality was to replace parts because the capability to repair them had not yet been developed. Early attempts with resins and fiberglass matting would either completely fail or read-through was common.

However, replacing the parts wasn’t always efficient or cost effective. When repair adhesives specifically formulated for composites were developed, it introduced a way to enable a straightforward, robust structural and cosmetic repair quickly and economically. (Consider a damaged fender on a hood assembly where a new hood is $3,000, the fender alone is $500, but $600 of repair labor will repair it. The repair will usually be much faster than ordering a new part and then bonding it in place and when done properly just as long lasting. Further, the repair will probably reduce the total amount of painting required and thus save additional time and money.

When determining whether to repair or replace a part, the period of time the truck would be out of commission must be considered. This includes the potential waiting time for parts to be ordered, shipped, received and supplied to the body shop for reinstallation.

A quicker turnaround is important and time is of the essence with heavy-duty composite repair, especially because of the ongoing truck driver shortage crisis (ABRN.com/drivercrisis) – a problem the American Trucking Association (ATA) expects to triple by 2020.

Any time a truck or trailer owner-operator – i.e. small business people who own, maintain and drive their own commercial motor vehicles – isn’t on the road, it means lost revenue. Fleets have the same consideration, multiplied across all the fleets – whether it is 40, 50 or any other number of trucks down for a day or longer. When any fleet operators aren’t hauling material, they are not making money, either.

According to the Owner-Operator Independent Drivers Association (OOIDA), the average salary in the United States for 2018 is $66,711 – roughly $1,282 per week – with a salary range of $57,000 to $79,000. When the vehicle body or trailer is non-operational, it reduces this income. Although it’s hard to put an exact value on the cost per each day a truck is out of operation – it varies by the number of miles typically traveled, current fuel cost, net average daily delivery, and type of tractor or cab, among other factors – the fixed costs of trucking, such as lease or truck payments and insurance, remain the same. (See “The Real Cost of Trucking – Per Mile Operating Cost of a Commercial Truck” infographic at ABRN.com/costoftrucking and calculate truck operating costs at ABRN.com/truckoperatingcosts.)

Seam and joint sealing preparation

Another aspect of heavy-duty truck repair includes seam sealing and sealing of joints. However, it is not always as thought out or well defined as it should be – and it’s a very important component of the repair process.

Any joints or seams in the area repaired need to be sealed from air, wind and water intrusion. In some cases – because the equipment is so large and the area to cover is sizeable – seam sealing application in some cases is treated as the “second-rate citizen” of the repair.

In reality, its importance should not be overlooked. Sometimes the least-costly material or one that has very low costs associated with its installation is chosen for seam sealing. For example, some body shops use inexpensive silicone caulk from a big-box, do-it-yourself (DIY) store.

The problem? When an architectural/construction material – such as caulk – is used instead of adhesive material specified for a vehicle, these selections may be made without much consideration as to whether the material will be long-lived or be the best choice for the service life of the truck.

This type of material is typically not engineered to withstand a great deal of vibration and exposure to the elements, potentially causing a repair or a sealed seam to fail and resulting in a repair do-over, a water leak, rust or various other problems. Instead, technicians should understand the importance of selecting materials compatible with the transportation industry.

For example, a leak from incorrect seam sealing could not only destroy cargo, but some of the heavy-duty vehicles also double as sleeping quarters. Picture someone lying in bed with a bucket trying to gather water from a leaky roof. An owner-operator or contract driver would never tolerate a leaky room at home, so it should not be acceptable in a sleeper cabin.

When using seam sealers to restore vehicles to pre-accident condition, a technician needs to understand when and how to use the right materials to ensure a proper repair the first time.

Seam sealers are available in both one- and two-component formulations. Two-component sealers will cure through a chemical reaction; one-component sealers cure through a moisture reaction. For metal-to-metal applications, use direct-to-metal (DTM) sealers for the best results and corrosion protection. (Look for an article on sealing and sound dampening, including the use of seam sealers, in an upcoming issue of ABRN.)

Making the repair ‘one and done’

The bottom line when it comes to performing a heavy-duty composite repair is to do it correctly the first time with a careful review of original equipment manufacturer repair documentation to see if specific products and processes are indicated for the repair.

The technician should look closely at the material that needs to be replaced while dismantling the vehicle. If the OEM has not specified recommended repair products, the repairer should attempt to duplicate as closely as possible the material.

Although it may seem more complicated and messy to use a fiberglass product, it never comes back to haunt you. Once the final heat cure has been done, the composite repair will not change or move and will not be visible. The repair is done and has been completed properly to bring the vehicle back to pre-accident condition.

This eliminates any need for a repair do-over, which keeps a body shop profitable and customers satisfied.

To learn more about repair adhesives and to sign up for training, visit www.fusor.com and www.i-car.com. For specific user instruction and technical data sheets for all Fusor Aftermarket Repair Adhesives solutions, go to http://bit.ly/2Et177w. For videos on Standard Operating Procedures (SOPs), seam sealing, composite repair, and bonding, visit https://bit.ly/2FuD0lj. Go to https://youtu.be/vzAKI5WxJWw for a step-by-step video of how to perform a composite structural repair using repair adhesives.