Here is an example of repairing an aluminum wheel: Peterbilt "Bud" wheel, made by Alcoa. Machined finish, very bad shape, many dings and deep gouges. Sanded with 220, 320, 400, 600, 800. Then, buffed with Yellow 10" airway and Brown Tripli Compound.
Buffing seems to have become known as a "black art" these days, no pun intended! Truth is, it is really not that complicated. The use of proper arbor speed for each metal on a bench buffer, hand held buffer, or drill is extremely important to achieving satisfactory results.
Equally important is the proper use of abrasive compounds and pads that are right for the job. Finally, whether it is aluminum or stainless, proper handling of the buffer or drill will have a significant effect on that shine quality. The key is to buff in the direction of the pad rotation, not against it. This applies whether you are doing a cut step or final shine. Always go the same direction. When using a bench buffer, the same idea applies, and its as much for safety reasons as the shine quality. Buff the part using the underside of the rotating pad, not the top side, or the part could snag and fly directly toward you!
Aluminum is a soft metal that requires careful attention paid to the buffing pad surface feet per minute (sf/min). Given a certain rpm, the larger the pad diameter the more sf/min produced. The recommended sf/min for Aluminum is 5000. The formula to calculate this is as follows:
¼ pad diameter * arbor speed=sf/min
For example, a 10” airway pad turning 1800 rpm:
¼*10*1800=4500sf/min. 4500 is very close to the 5000 recommendation, and would give very good results.
Buffing at speeds well over 5000 sf/min will cause a phenomenon called “molecular migration”. Excessive heat from buffing over 5000 sf/min. will cause the molecules in the aluminum to move around. This in turn creates “flow lines”, which are especially visible on fuel tanks. Therefore, for 1hp and larger bench buffer applications, use 1800 arbor speed and 10” pads. Be aware that smaller (3/4hp or less)1800 rpm buffers will not work well with 10" pads due to lack of torque, and 8" pads should be used. Another workable combination would be a 3600 rpm 1/3hp machine using a 6" pad. This will give 5400 sf/min, close to the recommended 5000 sf/min number. For hand held buffers such as the Dewalt DW849, use arbor speed of 2000rpm with 10" pads and 2500 rpm with 8” pads. DO NOT use a hand held 6000-7000 rpm grinder. These can produce sf/min of over 15000, well beyond the recommended 5000 sf/min. For hand held drills, a 2500 rpm arbor speed and 3" or smaller pads works well.
Buffing aluminum can be a multiple or single step operation depending on the condition of the surface. For surfaces that are heavily pitted, sanding is highly recommended. A good starting point is 320 grit paper, followed by 400 and 600 grits until surface is smooth and pit free. For lightly pitted surfaces, sanding is usually not needed. At this point, use our Tripoli compound with a pad designed for “cutting”, which means the initial buff from satin to medium shine. Impregnated pinhole pads, full disk spiral pads, or Blue/Yellow airway pads can all be used for the initial cut step. Follow the Tripoli compound with White compound and softer pads, such as standard shine pinhole pads, concentric full disk, and Medium airway pads. For the highest shine possible, finish with Ultra High Luster White compound and extra soft pads. Domet or Canton flannel pinhole, full disk, or airway pads work very well with the Ultra White compound.
Step 1: Sand with no heavier than 240 grit, then 320, 400, 600, and finally 800.
Step 2: Buff with "cutting" buffing pad and Tripoli compound (brown). Typically a yellow 6", 8" or 10" airway pad will be used.
Step 3: Buff with "finishing" buffing pad and White Compound. Typically a medium airway pad will be used in either Standard, Ruffle, or Pleated construction.
Step 4: (Optional) Buff with extra soft buffing pad and Ultra White Compound. Use either the Domet or Canton Flannel airway pads for the highest shine possible.
For light maintenance, use Busch Aluminum Wash before buffing. It removes light to moderate oxidation and brake dust for a super clean surface. Follow this with Busch Super Shine Aluminum Polish by hand or machine. Machine buffing will give a higher, longer lasting shine than hand polishing. Busch Polishing Kits are great for maintaining wheels and save significant time and effort over hand polishing.
To allow polishing of anodized aluminum, like the window trim on older vehicles, we recommend this removal procedure:
Step 1: Scuff surface with 1200 sandpaper
Step 2: Spray with EZ-Off Oven Cleaner and allow product to soak on aluminum for 3-4 minutes, then scrub surface with 4/0 steel wool to remove the anodize.
Stainless Steel is a hard ferrous metal that requires faster sf/min and more buffing heat than aluminum. The recommendation is 8000 sf/min.
For example, a 10” airway pad with 3600 arbor speed:
1/4*10*3600=9000 sf/min. This is a little high per the recommendation, but will still work well.
An 8” pad with 3600 arbor speed:
¼*8*3600=7200 sf/min. This is a bit low per the recommendation, but will also work well.
Therefore, for 1hp and larger bench buffer applications, use 3600 arbor speed and 10” pads. For 1/2hp and 3/4hp machines, use 8" pads. For 1/3hp machines, use 6" pads. For hand held buffers such as the Dewalt DW849, use full arbor speed of 3000 rpm with 8” or 10” pads. DO NOT use a hand held grinder. These can produce sf/min of over 15000, well beyond the recommended 8000 sf/min. The use of a hand held drill is typically not recommended for buffing stainless due to inadequate arbor speed and pad diameter.
To buff Stainless Steel, first assess the condition of the metal. If there is moderate to heavy scratches, sanding is recommended. Start with 240 grit and work up to 400 grit. Next, use Busch Emery Bar Compound and a “cutting” pad such as a yellow full disk spiral, Blue airway, or Red airway (for extreme cut). Follow this step with Busch Green Bar Compound and an intermediate buffing pad such as full disk concentric or Medium White airway. Finally, finish with Busch Ultra Green Bar Compound and either a Domet or Canton Flannel full disk or airway pad. This will give a mirror, scratch free shine on Stainless.
Step 1: Sand with 240, 320, 400, and 600 grit.
Step 2: Buff with "cutting" pad and Emery compound. Typically an 8" or 10" Blue/Purple airway pad is used for this. For extra heavy cut, use our Purple Pleated pad.
Step 3: Buff with "finishing" pad and Green compound. Use an 8 or 10" Medium airway in either Standard, Ruffle, and Pleated construction.
Step 4: (Optional) Buff with Canton Flannel airway pad and Ultra Green compound for the highest possible shine.