Stuck: Adhesion - BodyShop Business

Stuck: Adhesion


I love glue, too…

Sounds like a sticky situation to me.

When I was assigned the task of reporting on the current state of adhesive use in the vehicle repair process, I had no idea where the story might lead. For the easy, logical side of the story, I talked to some technicians and shop owners. I also talked to some insurance guys and adhesive manufacturer personnel.

So that about wraps it up then, right? Wrong-o epoxy breath!

While certain segments of the collision repair industry have adapted and found value in the use of adhesives, I was surprised at the skepticism that still exists regarding the bonding of non-structural panels on vehicles – due, in large part, to the fact that vehicle manufacturers still aren’t endorsing this as a repair method.

As I dug deeper and deeper into the theoretical side of adhesive bonding in the industry worldwide, I also was astounded at what’s driving the use of these products and at what a technically high level these adhesive manufacturers work.

Producing Energy-Efficient Vehicles
We all know that the federal government, in its great wisdom, has encouraged (legislated) vehicle manufacturers to improve the energy efficiency of their fleets. How deep are the driving forces behind the corporate average fuel economy (CAFÉ) standards? Who are the agencies and what are they doing to ensure future generations remain mobile? Let’s take a look.

1. The Automotive Composites Consortium (ACC) – GM, Ford and Chrysler formed ACC in 1988. Its mission: to conduct joint research programs on structural polymer composites in pre-competitive areas that leverage existing resources and enhance competitiveness.

One of their main goals was to develop technology that would produce reliable structural composite parts in high volume at a competitive cost. Under the umbrella of the United States Council for Automotive Research (USCAR), their work in these and other areas continues. (See

2. Partnership for a New Generation of Vehicles (PNGV) – PNGV is a non-profit organization that was established in 1992 by the Clinton administration. It’s a joint effort between the government (mostly The Department of Energy) and vehicle manufacturers for the research and development of new vehicle technologies that are safer, stronger, lighter and three times more fuel efficient. Their goal is to develop and validate cost-effective, lightweight materials technologies that will significantly reduce automobile weight without compromising vehicle cost, performance, safety or recyclability.

3. Oak Ridge National Laboratory (ORNL) – Oak Ridge is celebrating 60 years of serving America this year. For the sake of our story, we go back to 1992 when the PNGV identified the need for the ACC to develop technologies that would overcome hurdles in adhesive bonding of current and future automotive materials.

The Department of Energy has long promoted the use of lighter-weight materials in automotive structures and identified bonding as a critically important methodology. Why? Primarily because its use gives designers the freedom to choose from a variety of low-mass materials, including composites.

These adhesive research programs are being worked on by a diverse group of folks – industry people, university and government researchers, etc. – and are managed by both ACC and ORNL staff members. Their work includes evaluating environmental exposure, developing test methods, and working on rapid cure and surface preparation technologies.

4. The Adhesion Society – You think I make this stuff up? Of course there’s an adhesion society. In Blacksburg, Va., no less. Check them out at This group exists to promote the advancement of the technology of adhesion – and to make sure this knowledge is available to those who need it. At their last annual meeting, some of the seminars included:

  • Surface Preparation of Composite Materials for Adhesive Bonding.
  • Is It Really More Important That Paint Stays Stuck on the Outside of an Aircraft Than That Glue Stays Stuck on the Inside?

3M even sponsors an annual award for excellence in adhesion science.

Real World Applications
The truth is, the further I dug, the more fascinating things got for me. The government, industry, universities and scientific community are working around the clock to further utilize the use of adhesives.

Early on during the design of the Elise model, Lotus decided to use an aluminum space frame to save weight. Instead of welding, they decided that adhesive bonding would be the best method to provide accuracy and additional weight savings. Lotus called in TWI World Centre for Materials Joining Technology (a company in England) to help them design the bonded joints. Their study established the relationship between stress concentrations and the aspect ratio of the joint.

With Lotus’s existing knowledge of suspension load, they were able to design the bond areas. Says Daryl Grieg of Lotus: “TWI helped us get over some of our qualms about the testing process for adhesives.”

Then there’s Daniel Goodman and his crew at Electron Solutions Inc. in Maine. Their specialty is high-energy electron beam equipment and electron-beam-curable materials. While electron-beam generators produce radiation and require shielding to protect workers, the technology can be used for curing and adhesive bonding of composites.

Although the amount of composite is still small compared to steel, its use will increase as the ACC and PNGV agendas move forward. In recent years, Chrysler has displayed several all-plastic composite body prototypes at shows. Unlike conventional steel-bodied cars that are welded together, plastic vehicles are bonded together with adhesive. In fact, Goodman and his crew worked with Chrysler in 1999, comparing heat-cured and electron-beam-cured adhesives for the Chrysler Composite Concept Vehicle.

The electron-beam-curing process proved to be superior to heat cured and conventional air-dried curing processes. The beam curing also proved faster in giving Chrysler an under-two-minute cycle time versus many minutes for hot air bonding.

How do I know all this? Because this information was part of a paper presented to the Society for the Advancement of Material and Process Engineering. Their 35th annual meeting will be in Dayton, Ohio, later this year. Once again, scientists and researchers are getting together, sharing information. And much of it has to do with bonding.

Are We There Yet?
In a recent report to USCAR, the market research firm of Technology Assessment Associates wrote: “The ability of adhesives to bond dissimilar materials such as aluminum, polymer composites and steels to form large automotive structures will be a driving force on the growth of automotive adhesives…The use of synthetic materials is expanding throughout the vehicle as vehicle designers pursue aggressive design goals including the development of lighter, more fuel-efficient vehicles.”

But what the heck does all this really mean to you, the collision repairer?

While the technicians I spoke with seem comfortable working adhesive into their repairs, there’s been no sweeping endorsement for the collision repair industry to throw away their MIG welders and glue everything in sight.

GM, Ford and DaimlerChrysler have been markedly cautious in their recommendations to the repair community. (GM has published a Service Bulletin that outlines the repair method for exterior panel replacement on 2003 and earlier GM vehicles; Chrysler issued a technical bulletin #81-170-03005 in 2002 that outlines their weld and weld-bonding recommendations, and Ford did a Fordstar Broadcast to their dealer technicians that outlined the recommended repair procedure to bond door skins. As of this writing, this is the official take on the issue.)

As for the insurance people I spoke with, they were only comfortable with the “fix it the way it was built” line of thought. Understandable.

My conclusion? That the burden of bringing this technology to the next level is on the adhesive manufacturers. They need to build acceptance of these methods with carmakers and continue their efforts to educate all parties.

I understand that there are always diverse interests at play when any industry confronts new technologies. None of the parties wants to be held liable for any potential mistakes. And despite the ample crash-test evidence that we’ve all seen and read about, the vehicle manufacturers continue to insist that more testing is necessary.

Unfortunately, until the adhesive manufacturers get the OEMs to endorse this type of repair, they’ll continue to struggle trying to convince the repair industry to adapt adhesive bonding as a repair system – despite the fact that the science and the chemistry behind the bonding processes appear to be quite sound.

It’s time for our industry to take a step forward. The adhesive technology available today is widely used by the woodworking, plastics, textile, electronics and medical industries.

Doctors push wounds together and apply a bead of glue to the tissue – no unnecessary pain, no stitches, minimal scarring. For printed circuit boards, machines dispense 20,000 tiny, precise drops of glue. A chip is placed on each dot, it passes through an oven to cure and the failure rate is measured in parts per million.

Adhesive technology is also widely used in the aerospace industry – in fighter jets and in outer space – with the most sophisticated machines ever devised in the history of mankind.

I’m convinced. So what’s our industry waiting for?

Why does it seem that we are (pardon the pun) stuck?

Writer Michael Regan worked on the paint side of the collision repair industry for 36 years and lives in Northeast Ohio. You can contact him at [email protected]

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