Questions about turning Beryllium Copper

exkenna · Oct 19, 2018

Hey guys,
I could use a little help here.I have a local customer who has a job coming up that involves a good bit of turning and the material is beryllium copper. Yes, I am aware of the health concerns and safety precautions needed, no need to beat that dead horse.

Specifically: What edge prep and coating have you found that performs in this material?
It's smooth OD turning, no crust or interruption.
I need to order some test inserts so here are the 3 options I'm considering:

A) A stainless steel grade with sharp, positive edge prep and CVD coating

B) Steel grade with free cutting but tougher edge prep and black aluminum oxide coating.
This is a combination I've had good success with in medium carbon steels at high SFM's.
The Medium temperature CVD coating is polished and is super wear resistant.

C) A harder grade for Hi-Temp alloys with a positive, sharp edge and PVD coating.
(Doubtful this is correct for this material but thought I would list it as an option)

I'm leaning toward the Steel grade with the MT-CVD coating. Opinions from people who have turned this material?

Here's the steel grade with thick MT-CVD coating

ZCC CNG432-PM YBC252

fmari --MariTool- · Oct 19, 2018

I did a lot in my past. Little gummy but not too bad. I would treat it like stainless and you should be good. Sharper the better.
Dont run any tool dry !!!

Guest · Oct 19, 2018

I used to turn it all the time, back in the day when brazed carbide stick tools with equivalent of a C5 grade uncoated carbide was the best thing available. I think I have turned it once since insert tooling became available for wide spread use. I remember long tool life and good finishes even with the limited options back in the day. Considering that I believe all of the above will probably work great with out any noticeable difference among them. If a dead sharp stick would last 3 shifts + I am sure whatever you chose will be fine.

Milland · Oct 19, 2018

I haven't cut BC in decades, but I'd want a sharp insert with a wear resistant coating, or perhaps a DLC. I don't think I'd use the insert you show, I don't think it's free cutting enough, but I could be off base. If nothing else, I'd want an edge design that minimized "compacted/fractured" chips, as those could release more powdery chips (worse for inhalation risk).

A larger, cleaner chip that's able to curl enough to break and not be stringy seems ideal to me.

Just my $.02

exkenna · Oct 19, 2018

All Good replies.. thanks for leading me in the right direction.

Guest · Oct 19, 2018

Since all of the few responders haven't worked with the stuff in ages I wonder if it has been replaced by an alternative material or all of us left the industries where it is commonly used. It was a common material used for contact sockets and pins used in aerospace connectors, making those for second tier defense contractors in the 80's is where my experience with BeCu comes from.

uncledenny · Oct 19, 2018

I`ve burned a ton of it on a sinker but I don`t recall any of the mill/lathe guys bitching about it anymore than anything else!

spock · Oct 19, 2018

is the copper a high-hard flavor?

m98custom1212 · Oct 19, 2018

I turn decent of it @1-1.25 bar stock and treat like alum- sharp positive rake

exkenna · Oct 19, 2018

The customer mentioned its at heat treat so yes.
Trying now to find out what the hardness will be.

TRussell · Oct 19, 2018

exkenna said:
The customer mentioned its at heat treat so yes.
Trying now to find out what the hardness will be.

BeCu can be heat treated to a surprising strength. I've worked on parts that were heat treated to 180-200 ksi. We always used the same inserts that we used on 17-4 and 15-5, I don't remember offhand what they were. Most of the bushings that we used to make from BeCu are made from copper nickel tin alloy now. That shits even more expensive than BeCu.

billzweig · Oct 19, 2018

Machining depends quite a lot on the type of BeCu alloy and temper. I have worked with alloy 3 and alloy 25 both in the soft and heat treated form. I found the 25 in hard condition machines best and alloy 3 less so, but for all I have used the same tools - both carbide and HSS. All forms of alloys actually machine reasonably well. Tool form as for general turning of steel works well. Coolant important.

jjxtrider · Oct 20, 2018

This is one of the inserts I've used for many of the brass, bronze type alloys but the old grade was EH520Z . CNMG432 ESU Grade AC52U Carbide Turning 412436 - MSC

another good candidate I'm familiar with for similar materials is Tungaloy CNMG432 SS =grade AH120 . May be a better option if it wants to break easy in small pieces and you want longer/bigger chips .

.

Mydrrin · Oct 20, 2018

I found stainless type inserts work well with a bit slower than 316 speeds.

Philabuster · Oct 23, 2018

exkenna said:
C) A harder grade for Hi-Temp alloys with a positive, sharp edge and PVD coating.

Of your choices, this is what I would use ^^^.

We turn a lot of BC and we use periphery ground inserts. Leaves a beautiful finish and no smearing.

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Questions about turning Beryllium Copper

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