Specifying Tooling Surface Finishes

[richg1]

Hi,

I've seen a number of threads regarding tooling/plastic part surface finishes and wondered which standard or call-out is preferred by toolmakers? Grade numbers vs Ra values or perhaps something else?

Also is their an industry standard or reference guages for EDM surface finishes (ie. like mold tech)? I saw a mention in another thread that Charmilles may supply this type of info but could not find anything detailed on their website.

(ps. apologies if this has been answered in depth before but the eng-tips search engine is down)

Cheers...

 

[richg1]

Is answering my own thread ok?

SPI (

http://www.plasticsindustry.org/)

have a sample plaque of hand finish specifications for injection moulding tools which we just received in the post. Definately worthwhile for anyone designing plastic parts as it covers tooling finishes from basic bead blasting right up to a mirror finish with diamond buff.

So anyone got anything for raw EDM finishes?

ps. I don't work for SPI

 

[btrueblood]

see:

http://www.nolansupply.com/superprecision.asp?supercategory=Surface+Finish+Gages

 

[richg1]

Thanks BTB,

To add some more info to this thread I should mention photo-chemical etching of tools. This can be used to produce various surface finishes ranging from very fine stipple finishes right up to leather grain.

One of the most well known names is Mold-Tech (

http://www.mold-tech.com).

Another is the SEC group (

http://www.surface-etching.com).

I think they have quite a big presence in Japan and Asia.