Polishing Cast Aluminum.
Polishing Cast Aluminum.
(OP)
I recently had a custom part cast for me by a small company. I am fairly pleased with the result but while polishing it I have noticed a number of small pinholes in the casting that will be detrimental to my planned high quality polished finish. I have tried to sand them out but with no luck. What are my options here?
Am I left with a choice between a decorative chrome finish where the copper plate will (hopefully) fill in the pinholes, tig welding the holes (long, laborious process and possibly opening up more holes) or is there still a way I can acheive a good surface by filling in somehow.
The part is mainly decorative and is made from A356 with some 3003 welded to it. Thanks for any help.
Am I left with a choice between a decorative chrome finish where the copper plate will (hopefully) fill in the pinholes, tig welding the holes (long, laborious process and possibly opening up more holes) or is there still a way I can acheive a good surface by filling in somehow.
The part is mainly decorative and is made from A356 with some 3003 welded to it. Thanks for any help.





RE: Polishing Cast Aluminum.
RE: Polishing Cast Aluminum.
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RE: Polishing Cast Aluminum.
Regards,
Cory
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RE: Polishing Cast Aluminum.
RE: Polishing Cast Aluminum.
I have had a lot of Al parts electropolished but never any 356. I won't hazard a guess on how alloy will polish.
Bright dipping is another possibility but I've had varying results with 356 permanent mold castings. The problems were mainly due to the high Silicon content.
How is your casting made?
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RE: Polishing Cast Aluminum.
If I understood the plater correctly I don't think he is going to electropolish. He is first going to clean and polish, then copper plate, then give back to the polisher who in the act of polishing will force the copper into the holes and build up enough to fill them. If warranted another copper-plate and polish can be done(or a few more if the holes are big). Then chrome. Hope I have that right.
RE: Polishing Cast Aluminum.
RE: Polishing Cast Aluminum.
I would keep my all my options open for either the mechanical burnishing or the electropolishing. Essentially what is happening is that the copper is being burnished. If I were to use plating to correct the finish I would trend towards the system suggested by swall.