Surface finish for aluminium parts?

[yadnom1973]

I have a project I’m working on with parts cut from aluminium and to see if I can save some money I’ve had some of the low tolerance parts water jet cut. The problem I have with these parts is that the CNC’d parts will have a clean milled finish and these parts being 2D cut from 15mm sheet will have the sheet finish on the faces with blemishes and scratches from handling and on the cuts a mix of grinded and the shot blasted finish water jet leaves.

I need to find a way to create a unified finish on the parts before anodising them. I could shot blast the lot, maybe try and do this myself because if I have this done it could be expensive and negating to some extent the savings from having them waterjet cut.

These parts are made of some complex shapes with some internal corners with radius as small as 5mm. Any sugetions on how to clean all these parts up and leave a unified surface finish?

[Hitch]

Media blasting of some sort would be one way, or vibratory cleaning... basically put the parts in a heavily vibrating drum with a suitable polishing media. Fairly specialist though, and depends on the parts if thats suitable.

[yadnom1973]

Thanks for the help Hitch. Blasting and tumbling of some kind seem to be the only two options that people are mentioning. I’m not sure which would give a better finish or which is more cost effective. I’ll make some calls tomorrow and see what kind of money people want for doing this.

[Rorschach]

How many parts are we talking about? Homemade tumblers can be super cheap and simple to build.

Every so often I need to tumble jewellery parts. The special machines for this are rather pricey and it's something I do once or twice a year at most. My solution, a good tupperware. I put the parts and the tumbling pins in the tupperware with some soapy water, wrap it in a towel just in case there are leaks but also for noise reduction. Put a film on the tv and shake it around gently. Does a great job.

[yadnom1973]

I suppose on average the parts are about 70x70mm and 15mm to 30mm thick. There are 40 parts total per unit, at present 9 of them are cut out with a waterjet.

[Bob225]

cut and buff to a shine with polishing wheels and compound, any scratches can be take out with scotchbrite pad - I have done plenty of model/Rc car parts and they come up fine

[Dave54]

Never had any done, but a mate of mine used to get small parts for bikes anodised. As far as I can remember they went to the polisher first.
There's a bit here about anodising prep.
http://metalfinishingsltd.co.uk/article ... anodising/

[Rorschach]

Ahh ok, my method won't work then.

[yadnom1973]

The water jet parts leave a shot blasted and grinded finish on the cut, this and the scratches and marks from handling means that some kind of quite aggressive work would be needed if I was take it to any finish other that a shot blasted one. I’ve been experimenting with the scotchbrite pad and this has been surprisingly effective. Thanks for the help guys.