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der-lee77
11-12-2007, 12:14 AM
Hello, i'm looking for some advice because i will make a parts extrusion with H-13 steel and i need brilliant finish surfaces. do you have any idea for that type of finish?

Thank you!

derly

Evan
11-12-2007, 01:19 AM
H13 will electropolish to a brilliant chrome like finish.

Fasttrack
11-12-2007, 02:44 AM
not sure that it applies here, but i'd like to know a little more about broaching finishes... if that is the correct term for it. I've read about using say a wheel with an ultra smooth surfaces and alot of pressure to "press" a finish on a part and that applies for all sorts of shapes provided you have the broach for it.

Evan
11-12-2007, 04:49 AM
I believe that is called "hobbing". It's the same word as a hob for making gears but describes a different process when hobbing a mold. The master is forced into the material making a negative of the original, finish and all.

lathehand
11-12-2007, 08:18 AM
Use the approprate supplies with the needed skills and you will have a mirror finish. Send me the die and I will bid on it. Sorry if this was not too helpful but I am not interested in helping American job loss. Or is extrusion now done in home shops?

lazlo
11-12-2007, 09:53 AM
Fastrack is talking about a carbide burnishing tool. They plastically deform the metal into a very fine surface finish.

Here's a carbide burnishing roll for a lathe. There are micrometer adjusted internal burnishing rolls to "polish" bores too:

http://i22.ebayimg.com/08/i/000/c2/a2/c36e_1.JPG

Peter N
11-12-2007, 11:14 AM
Hello, i'm looking for some advice because i will make a parts extrusion with H-13 steel and i need brilliant finish surfaces. do you have any idea for that type of finish?

Thank you!

derly

Well the grammer there is slightly odd, obviously not a native english speaker.
I can't understand if he wants to make an extrusion die from H-13, or wants to actually try and extrude H-13, which would of course be a bit tricky :)

A brilliant finish, other than on the die itself, is also of course quite impossible due to viscous drag on the material as it passes through.
FWIW we almost always make moulds/dies that require a high polish from EN30B rather than H13, as the higher nickel content makes the finish both brighter and longer lasting.

Peter

lazlo
11-12-2007, 11:22 AM
FWIW we almost always make moulds/dies that require a high polish from EN30B rather than H13, as the higher nickel content makes the finish both brighter and longer lasting.

You Brits use funny materials designations Peter :)

I had to look it up -- EN30B is close to AISI 4340.

Swarf&Sparks
11-12-2007, 12:46 PM
I just use green scotchbrite on 316

peter08
11-16-2007, 05:38 PM
not sure that it applies here, but i'd like to know a little more about broaching finishes...
I'm sure this has alot to do with what type of broaching you're doing. Rotary Broaching leaves a really sharp corner, but surface finishes often depend on the material. Check out my video to learn more: http://www.slatertools.com/video.htm