Differences in aluminum, steel impact repair process

Aug. 15, 2014
The physical properties of aluminum are different than that of steel, making the repair process, and in turn, the end results, quite different.

Have you heard about the 2015 Aluminum F-150? Of course you have, unless you’ve been living in a paint booth somewhere. Aluminum is the topic du jour and the hype is only escalating.

The collision repair industry has been through significant changes before and has weathered the storm just fine. Need I remind you of the unitized structure, waterborne paint, ultra-high strength steels and Lean Manufacturing? Early adopters and shops that have been adjusting to these curve balls as they came along will have little difficulty making aluminum repairs mainstream. For shops that have not adjusted as the industry changed it may take a little more time and investment, but now would be a good time to make those upgrades.

When new technologies or big changes come along in the collision repair industry, the hysteria and shady sales pitches are sure to follow. Beware the salesman that tells you that you need special tools and products specially formulated for aluminum repairs.

Yes, some special tools and equipment will be necessary but most products and materials that are used for steel repair can also be used for aluminum repair. There may be subtle process differences such as abrasive grade adjustments but 3M’s position, with very few exceptions, is that all materials currently used for steel repairs can be used for aluminum repairs as long as they are used in accordance with directions for use.  It is also important that tools and materials used for steel repair are kept separate to avoid cross contamination.

The same seam sealers, body fillers, undercoats and abrasives can be used on both substrates. Just knowing that drastic material changes will not be necessary should alleviate a great deal of anxiety. The difference lies not in the products and materials needed for the repair, but in the repair process itself.

The physical properties of aluminum are different than that of steel making the repair process quite different. Steel has a memory when bent or deformed and has a tendency to go back to its original shape during the repair process. With steel, heat can aid in the reforming process but may not be recommended on many of today’s high strength steels.

Conversely, aluminum has a tendency to remain in its current shape or remain deformed when damaged. The grain structure of aluminum differs from that of steel because it is much less inclined to re-align during the repair process, and unlike steel, aluminum should always be heated during straightening.

This can make repairs difficult and require different equipment and more finesse and patience. A trained and experienced technician will also be required because if the aluminum is accidentally stretched while repairing, the panel is no longer repairable.

Aluminum dent pulling systems should allow the technician to keep pulling pressure applied while the damaged area is heated and massaged back into shape. The equipment is very different and more expensive but the materials are still the same in most cases.

When finishing the repair with body fillers, most premium body fillers and glazes contain high-quality adhesion promoters and are approved for use on aluminum when directions and Standard Operating Procedures are observed. These premium fillers can be used on bare aluminum or over epoxy primer as some OEMs require. When sanding, follow the grade recommendations of the car maker who will generally recommend a finer grade when working on aluminum vs. steel and never coarser than grade 80. Special aluminum compatible abrasives are not necessary, but never use the same sheet of sandpaper on aluminum if it was previously used on steel. The abrasives are the same but it is a good idea to segregate them in separate cabinets according to substrate.

Many technicians think that because aluminum doesn’t rust, corrosion protection is less important or even unnecessary. Sealing repaired joints tightly during repairs is very important to prevent oxidation and corrosion from occurring. Applying protective coatings like anti-chip coatings and undercoating is also necessary to protect the aluminum body. Stone chips can start the corrosion process on aluminum by allowing oxidation to creep under the paint film and cause blisters known as filiform corrosion. 

After heating or using dent pulling equipment on aluminum, a cavity wax must be used to re-seal the surface of the aluminum on the back side. The back sides of any welded joints also need to be coated with a cavity wax. The corrosion protection process is very similar to that of steel, and the products that can be used are the same. No specially formulated seam sealers, rust-proofing or anti-chip coatings are required -- the same products used for steel can all be used during aluminum repairs if the directions for use are followed.

Although the aluminum panel bonding process is often slightly different than the steel bonding process, the 3M™ Panel Bonding Adhesive is also compatible and OEM approved for aluminum. 3M Panel Bonding Adhesive has been used to bond aluminum panels for nearly 20 years and is specifically recommended by Ford for the repairs to the 2015 Aluminum F-150. Panel Bonding adhesives undergo extensive testing in order to be specified by a car maker so there is no question about its ability to bond aluminum parts successfully.

Aluminum has been used for vehicle construction for decades but this resurgence will have some significant impact on the shops, the most significant of which will be the new equipment cost. From hand tools to welders and riveters there will be many big ticket tools that will be required to repair the F-150 or any other aluminum vehicle. There will be some lower cost alternatives in some cases. Ford will not require a permanent aluminum clean room but will recommend at the least a curtained off area.

This would be a good time to examine overall shop hygiene and look for improvement. With aluminum and other different substrates soon to arrive, the shops are going to have to improve cleanliness and handle the car with hygiene in mind. Even with a curtained work area it’s very likely that steel dust particles will make their way to the aluminum vehicle. The solution for that situation is to clean the panels well, immediately before applying any coatings or fillers.

The use of self-generated vacuum tools can also be used to keep the dust particles to a minimum while keeping the equipment spend down.  It will be important to evaluate the equipment needs and to prioritize what is really needed and what can be done with existing equipment. 

It remains to be seen how the adjustment to mainstream aluminum repairs will go for collision repair shops. Many shops have made similar adjustments in the past and are well prepared to make this change without much difficulty. The advent of waterborne paints had an impact on the paint shop whereas the aluminum change will impact the metal shop and leave the paint shop, for the most part, unscathed. The good news is that there may be small adjustments in the paint shop but nothing major.

The other good news is that the allied materials needed for aluminum will also change very little even though some marketing campaigns may say otherwise. You will not have to concern yourself with wholesale changes or many additional part numbers for materials, which frees you up to spend your energy sorting out the equipment needs and obtaining training for the technicians.

3M automotive Aftermarket Division now has available Standard Operating Procedures for aluminum repair. Visit www.3Mcollision.com/aluminum for more information.

Advanced Tools and Product Solutions Make a Difference

 

Tackling aluminum repairs in your shop?  Here are key things you need to know:

·      You will need some special tools, but many standard tools and products will work

·      Separate tools and work areas to avoid contamination

·      The science of the substrate drives the process

·      Always follow the Standard Operating Procedures!

·      Corrosion protection IS critical

·      Use this opportunity to review shop hygiene

·      Now is the time to train your technicians for tomorrow’s repairs

 

For more information about 3M products and solutions for aluminum repair, contact 1-877-MMM-CARS, contact your local 3M Distributor or 3M Sales Representative or visit the website at www.3Mcollision.com.

About 3M

3M captures the spark of new ideas and transforms them into thousands of ingenious products. Our culture of creative collaboration inspires a never-ending stream of powerful technologies that make life better. 3M is the innovation company that never stops inventing. With $30 billion in sales, 3M employs about 88,000 people worldwide and has operations in more than 70 countries. For more information, visit www.3M.com or follow @3MNews on Twitter.

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