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Need aluminum coating for wear, release, and smoothness

I have an aluminum part that needs to be hardened to protect from abrasion caused from scraping/cleaning to remove residue/monomers which are a byproduct of plastics extrusion. The part has a flat surface 20" x 20" which needs the protection, it is 1.5" thick. I also need a very smooth final surface, about 4-5 RMS. A good release characteristic would also prevent the buildup of residue/monomers. What kind of surface treatment would work well for me? I have 22 of these parts that need to be modified.

Perry Hartge
machine design - Mobile, Alabama
2003

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First of two simultaneous responses

You could look at Teflon applied by a certified applicator, but scraping might not work on it. That is an extremely relative term. Another option would be electroless nickel. An RMS of 4 is smoother than glass, and I doubt if any plating system can maintain that since the preprocess of aluminum for plating will cause some degradation. Of all the possible coatings, EN would be the cheapest close approximation. For real mold release, go to EN with Teflon codeposited. There are not many places that offer this and it does cost more, but not much sticks to it for long.

Finally, you might look at some of the options available from physical vapor deposition. It is thin, but very hard and with a low rms, not much will stick to it. I would suggest that you have only one done as a trial part before committing the entire lot. This checks the applicator as much as it does the process.

James Watts
- Navarre, Florida
2003

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Second of two simultaneous responses

Hard coat anodize, electroless nickel or electroless nickel Teflon co-deposit may do the trick. Parts may have to be polished afterwards to get the desired RMS.

Todd Osmolski
- Charlotte, North Carolina, USA
2003

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2003

One option to investigate would be co-deposited electroless nickel.
Teflon and silicon carbide are two substances that can be co-deposited with EN in order to modify the surface properties (hardness, friction, etc.).

Toby Padfield
- Michigan