How do I finish Aluminum?

[david90]

Originally Posted by HelicopterJohn Here is an example of what a friend of mine did with a little polishing effort.

What are the steps to get this finish and how long does it take?

[HelicopterJohn]

Hi david90,

My friend who machined and polished those parts lives in Iowa and is a CNC machinist by trade. I am sure the parts you are looking at were produced on a CNC machine. The only thing I know about the process was that he used Eastwood Premium Buffing Composition (emerald green) part # 529-GRN-B Green Brick. This product is available at MSC. Looking at the label it was designed for platinum chrome, and stainless steel to impart a high luster. As you can see it does a really nice job on 6061T6 Aluminum.

As others here would agree, the initial finish of the part depends on what you have to do in the finishing process. Polishing by itself will not cover up a poorly machined part, only shine it.

Personally, I have a motor (industrial strength) with shafts that extend on each end. On one end I have a 8 to 10 inch buffing wheel and the other end I have a scotchbrite wheel. I use the scotchbrite wheel to remove any (minor) imperfections and use the buffing wheel with the above mentioned compound to polish the parts. Polishing small intricate parts will possibly take other tools, steps and methods.

I can get a fairly nice luster on small Aluminum parts in a matter of minutes if the part is easily polished (no internal contours).

John

[fredhh47]

I use a quick process for a "general purpose" finish on a lot of machined parts. When I am done with all machining and general deburring, I use a slow, oily wire wheel to produce a smooth, directionless finish on most any aluminum. A medium wheel, about 6 or 8" in diameter is best, turning at a few hundred RPM. I apply whatever oil is handy, motor oil is OK, to the surface of the part and brush all over the part. The beauty is you can turn the part any which way to get into corners, slots and other details, without leaving criss-crossed tracks on the part. If the wheel is running too fast, besides wearing a lot of the oil, you will get a dull, galled surface, the same applies if you don't use enough oil. Best to wear vinyl coated work gloves, a long sleeved shirt, and a full face mask, or you will need a shower. But the results are terrific. Not shiny, no tool marks, and fairly resistant to weathering. If you want basic corrfosion resistance, look into commercial "Alodine" solution, a chemical conversion coating that adds nothing to the dimensions of the part, but retards corrosion. Do a Google search for "Alodine" or "chromate conversion" and you will turn up several sources. Auto refinishers use it as a paint prep before painting aluminum. Be sure to follow the instructions closely and use de-ionized water when it says to rinse the part well.

[blackbeard52]

For years we used a drill disk pad available at body shop supply stores and tool suppliers. it has a velcro like hook material on the pad. Simply attach Scotch Brite pad and insert it into a drill press...Cutting the pad round kept it from coming loose often. This did a quick nice job giving whatever finish you needed (depending on grit). Also we used cloth pads soaked in oil and smearing it with valve grinding compound. Gives the swirled effect commonly called jeweling.

Bob

[Rally]

If applicable and or feasible anodizing goes a long way. That is what I do to some of the parts I make. When polished a anodized part will stay shiny much longer. I make bike parts and have found that to be true.

[Martin 007]

Thanks for the info guys. And that is a great looking rotor head your friend has there.

[juliancrouch]

May be a little late for this, but if you have a buffing machine, you can use 3M buffs for a nice satin finish, or of course you could actually buff it to as shiny as you want it. Buffs are fast, easy to clean up, and cheap.