Bonding together

Panel and weld bonding are ever encroaching on the panel beating industry. Bruce Gascoigne, commercial products development manager for Lord Chemical Products (Australia), looks at some of the issues involved with the process.
The areas of use for adhesives in the manufacture of cars overseas appears to be misunderstood, ignored or overlooked by the repair industry. Not only does this situation have to change, it has to change rapidly. There are many cars, including local models, where failure to use the proper performing adhesive on certain repairs will impact negatively on the safety of the repaired vehicle. This issue is only going to increase in importance in the future.
The challenge for the body repair technician is to determine the nature of the product used in any joint that is to be repaired. Without assistance from the OEM, this is going to be difficult, but not always impossible.
Recently we have seen a concerted effort by the OEMs to qualify bodyshop-capable adhesives and sealants for repair of vehicles. Some companies are addressing this issue with more 'gusto' than others. However, there appears to be a growing interest by OEMs in involving themselves in this area.
We have seen a considerable effort in the United States from the 'Big Three' to determine suitable adhesive and weld-bonding procedures for both recall and general accident repairs. The information generated from these efforts is now feeding into the aftermarket.
It is important to understand that the new stance OEMs have taken on adhesives has significant implications for the aftermarket industry. It means a whole new area of expertise needs to be developed within the bodyshop. Unfortunately, the aftermarket industry is not properly trained or prepared for this change. There needs to be an urgent upgrade of the education programs to reflect and understand the use of adhesives and the means to repair bonded and weld-bonded components.
I am not well-versed in the politics of the auto industry on a 'cradle to grave' basis. However, I think it is in the interests of the OEMs, insurance companies, aftermarket industry, trade groups and body repair technicians themselves to develop the rapport required to create consistent repair procedures. These must ensure the structural integrity of the vehicle is maintained in the post-repair environment. Like the move to force the use of PU adhesives for bonded windscreens in past years, it is important that adhesive technology is properly used.
What is being done to investigate the use of adhesives in the automotive aftermarket industry? To assist OEMs and the body repair industry alike, some adhesive companies are working hard to generate data that can be used for predicting behaviour in crash situations. These companies are benchmarking the performance of bonded repairs against traditional weld repairs, and original cars, straight from the factory.
Combinations of rear impact, rollover and frontal offset impact tests are being carried out. These tests are designed to evaluate the adhesive performance under actual crash conditions. So far, the evidence is that adhesive repairs on metal panels perform as well as traditional repairs and OEM assembly.
Thus far, only secondary panel repairs are considered practical for using adhesives. The reason they should not be used on primary structures is they may make the part entirely too strong. The potential effect is to remove the crumple zones built into the vehicle.
As OEM use of adhesives increases, we expect vehicle designs will allow for the use of adhesives in repairs of primary structures. The time is approaching where the structure of the vehicle is about to make such rapid moves aided and abetted by adhesives. The only questions that remain for members of the body repair industry are: Are you in the race? Or are you still on the way to the track?

Present areas of panel bonding use:

1. Closure panel hem-flange bonding.
2. Space frame assembly.
3. Frame door opening panel to reinforcements.
4. Strut tower attachment.
5. Cross floor seams on the floor pan.
6. Rear quarter panel to wheel arch.
7. Insert bonding of firewall to floor pan.
8. A, B and C pillar reinforcement around hinge mountings and striker plates.
9. Roof skin (turret) attachment.
10. Roof bow attachment.
11. Plastic closure panels (doors, decklid, liftgate, engine hood).
12. Plastic front and rear quarter panels.
13. Sunroof opening surrounds.
14. Sunroof opening panels.
15. Fixed glass bonding (windscreens, rear lights and side glass).
16. Plastic crash pad assembly.
17. Plastic and glass lamp assembly.
18. Plastic/metal grille opening panels.
19. Plastic wheel cladding.
20. Plastic rocker covers.
21. Plastic sump pan.
22. Composite springs.
23. Spoilers and plastic add-ons.
24. Radiator support panels.

Future new areas of use include:
1. Front and rear frame rails.
2. Rear beaver panel attachment.
3. Modular door frame to body roof.
4. Rocker/sill panel attachment.
5. Dissimilar metal combinations for various areas on the vehicle.

Note that in many of these areas, the adhesives will be used in combination with welding. In some cases the adhesive is used on its own.