Bench Test.txt

Bench Test

Box under strap:

Name: Automix Panel Bonding Adhesive
Made by: 3M Australia. Tel:136 136 Fax: (02) 9677 5636
Key feature: Lifetime warranty

A strong bond
Allan Higginbotham tests the strength of 3M's panel bonding system and looks at the advantages of using such a process.
Twenty years ago the welding of body panels was mainly done with the oxyacetylene process. Then came MIG welding and today most workshops use a combination of MIG and resistance spot welding. Some workshops are also using panel bonding adhesives to fit quarter panels, roofs, van sides and door skins. These types of adhesives are only used on outer body panels.
The adhesive is a two-part epoxy mix, the mix is achieved by the design of the Automix nozzle, which completely mixes part A and part B before the adhesive is applied to the panel.
The adhesive has a work time of approximately two hours, cure time is approximately four hours and this may be accelerated by heat. A structural adhesive can be defined as chemically reacting adhesives that create high strength bonds. Their shear strength can be measured from about 7Mpa to 80 Mpa. Structural adhesives use mainly derivatives of three basic polymer systems: epoxies, urethanes and acrylics.
3M supply all the materials required to get you started in the panel bonding process. The range includes a high quality applicator gun, which I found quite easy to control as you do not want to waste adhesive. We used the adhesive on a short cut rear quarter panel and I found the process very simple to use and it was a substantial time-saver as compared to normal welding and filling methods.
Some MIG welding was used on the butt joint of the quarter panel, but 90 per cent of the panel was bonded. If the wheelarch area is welded it is always an area of concern for future corrosion. Bonding eliminates this problem as the joint is completely sealed. Adhesive bonding would also be suitable for small rust repairs; panels could be lapped and bonded and edges could be welded; this would cut down on panel distortion and finishing time.
I manufactured a rail section on which the top and bottom panels were bonded. This rail section was damaged and then pull plates were bonded to each end and used to repair the rail. It was found that the bonding did not break and this assured me that the strength of the bonding adhesive was remarkable. You would not normally need to do this type of test with pull plates as the manufacturer has extensive documentation of vehicle crash tests using adhesive bonding. 3M guarantee the bonding adhesive for the life of the vehicle.
When fitting a panel which requires adhesive bonding, it is essential that a dry fit is done before adhesive is applied. After the adhesive is applied the panel is clamped in position for approximately four hours. The adhesive also contains glass beads which work as built-in spacers for optimum bond line thickness. It is recommended when using this adhesive that gloves are worn.
Panel bonding adhesives are used extensively overseas and the results are quite remarkable. Some advantages are:
1. Adhesives produce a continuous bond and thus distribute stress loads over the entire jointed area. This eliminates local stress concentrations and produces joints of greater strength and rigidity.
2. Adhesive bonding provides continuous contact between surfaces, thus sealing as well as bonding in a single operation. This eliminates the time and cost of separate sealing operations and allows the sealing of joints where it might not otherwise be possible. This sealing also eliminates entrapment of corrosive moisture in the joint area.
3. Time-saving on repairs is also why repair shops should consider using bonding adhesives. When fitting a roof panel it is estimated that there would be a 50 per cent saving on time as compared to traditional welding and sealing processes.
In summing up, I consider this bonding adhesive to be an essential part of smash repairs and the more you use the adhesive the more you realise how simple it is to use. Also, it is evident that there is a substantial time saving using this product as compared to conventional joining methods. If you have used bonding adhesives years ago and were not happy with them, give this one a try. I am sure you will be pleased with the results.

Box:
Instructions for use

1. Sand area to be bonded with a suitable sanding disc or abrasive wheel.
2. Straighten all metal edges and 'dry fit' part.
3. Clamp part in place and check for fit and alignment.
4. Remove panel and apply bonding adhesive to all areas to be bonded.
5. Using a plastic spreader, spread the adhesive to provide a base (primer coat).
6. Apply an additional adhesive bead approximately 6 mm from the inside edge of the replacement panel.
7. Place replacement panel onto vehicle and clamp in its proper position.
8. Remove any adhesive which has squeezed out of the joint, using the plastic applicator.