Brass that insulates

[eromlignod]

Hi guys:

I'm looking to replace a small brass part in an application. The replacement material has to have a tensile strength and surface hardness at least that of brass and must be tough enough to take a hit now and then like brass without shattering. It also needs to be machinable...maybe not exactly as machinable as brass, but at least doable with carbide tooling. Ideally it would be available in rods of around .625" dia., but I'll take what I can get.

Here's the catch: it cannot conduct electricity. It doesn't have to have an extremely high dielectric strength, since there will not be high voltages applied across it, but it should be able to take 5 Vdc without breaking down.

So far I have tried fiberglass rod, but it doesn't have the tensile strength in the lateral direction I need, so it tends to split when pulled from the sides. I also tried Garolite G-9, which worked well strength-wise, but didn't have as good a surface hardness as the brass and can have brittle failure if struck.

Hopefully there is some type of material that is not too exotic or overly expensive that I can use. Any ideas?

Thanks for all replies.

Don

 

[kenvlach]

Maybe Al 7075-T6, hard anodized for insulation.
Al 6061 is less expensive if don't need as much strength.

 

[eromlignod]

How tough is the hard anodize? Basically the rod has a hole drilled through the side of it near the end and a steel wire passes through it. The wire will have 150 lbs of weight hanging off it, but must not electrically contact the rod or inside the hole. The wire can move around at times and gouge a little.

Don

 

[kenvlach]

Is the hole axis vertical (as a guide) or horizontal (with rim exposed to high wear)? Wire & load have some speed?
What impact?
Post a diagram or photo somewhere, as your objective isn't obvious (& non-conductive brass is not right, either).

Maybe use a piece of brass tubing as a bushing in a plastic part.

 

[IRstuff]

Maybe you can make a ceramic insert for the brass outer form?

TTFN

 

[MechanicalChef]

It might be worth your effort to contact Cornerstone Research Group.

http://www.crgrp.net/hardcoat.htm

This material might get you to where you want to go. I know it's tough and hard. The Conductivity of red-brass is about 150 (W/m*K), yellow brass is about 120. This stuff is 3.5W/(m*K).

 

[RPstress]

I may be misunderstnding what you mean by "...tensile strength in the lateral direction...". Do you mean that the rod broke due to bending under a lateral load, or that it spit apart under a load which was tension across the rod diameter?

If the latter, then depending on your strength requirements, a short fiber reinforced plastic part might do, perhaps glass in nylon or polyester or maybe PEEK or PSU.

If the short fiber-part properties weren't adequate, you should be able to get a rod made that isn't unidirectional material.

If it's the former, i.e. glass wasn't up to the job, then there are some stronger non-conducting fibers about. It depends on the strength level you need.

Do you have a numerate strength requirement?