matte finish on small delrin parts

[justin8888]

Ive been researching this for a while and have found some but not much information. And what I have found has been conflicting.

I'm looking to finish a series of small, mostly black but some natural/white delrin parts. The actual CNC machining is being done by a shop. They will be delivered to me cleaned and deburred. So I am expecting them to arrive with mill marks. I would like to remove the mill marks and leave the parts with a uniform satin finish, even so far as a lightly roughed/textured finish. Basically something that will hide scratches and provide grip while maintaining decent aesthetics.

From all that Ive read, theres basically 3 options for this.

1. sand paper, then scotch brite pads
2. vibratory tumbler with ??? media (walnut shells, beads)
3. glass bead blast at low pressure with fine or extra fine grit glass

I would like to avoid the sandpaper route if possible as its a bit labor intensive and Ive got a decent amount of parts to do. If the vibratory tumbler works, that would probably be my best option as its the cheapest in terms of new equipment and likely the most consistent, but none of the options are cost prohibitive so whichever works best is what im after. Im a little concerned about the stress that the vibratory tumbler will put on the parts as some have thin walls which are strengthened by the completed assembly. Though I suppose I could tumble them full assembled.

I like the finish that blasting leaves on aluminum and if I could get the same on delrin, I would go that route.

Does anyone have experience with these methods and have a recommendation? Pictures would be awesome if you have them as well.

Thanks

 

[Bob Korves]

I have done all of those and all of them work. Vibratory tumblers are quite gentle to parts and won't damage them. Tumble style tumblers can be more aggressive and hurt delicate parts, depending on a lot of variables, but also do the work faster with the same media. Firearms sources are good places to get a vibratory tumbler at a good price. Blasting needs to be done carefully to get consistent results, and requires hands on work, as does sandpaper and Scotchbrite. Vibratory tumblers work while you do something else. The media is the critical thing for vibratory tumblers. Perhaps a web search will lead you to what people use on Delrin/acetal.