Machining beryllium copper

[ouldeeps]

Does anyone know anything about machining beryllium copper? Have got a possible job where I have to turn down 9.5mm bar to 5.5 and thru drill it 50mm long. Any help on speeds feeds and correct tooling would be appreciated!!

[Mcgyver]

yes, read up on the health hazards, its potentially deadly (not an exaggeration). its the inhalation of dust or getting it in a cut and consequences can be amputation or beryllium disease (lungs) which can be fatal. Now machining is suppose to produce chips not dust, but some dust is created and you certainly don’t want to be abrading/filing it without precautions

One of the problems is that only certain people are severely affected by small exposures, but there is no way to prescreen. Personally I don’t want it my shop, maybe I’m being paranoid but if you go for it at least you’ve had the heads up and can install coolant, dust/fume extractor ect

[Geof]

Mcgyver is correct.

There was a question on beryllium copper a couple of years ago and I looked up some information:

Obviously it was at Christmastime.

Beryllium Copper:

This brought back memories from my apprenticeship some forty odd years ago when I got to machine stuff like this along with aluminum bronze, nickel alloys, etc, all with high speed tooling; YUCK! So because the grandchildren are at the other grandparents today I had a bit of free time (by the way; Merry Christmas) and went googling. Everything between >> and << is what I found on different websites.

From one source:

>>Beryllium copper: Adding about 1.8% by weight of beryllium and about 0.2% cobalt to copper provides an alloy with strength comparable to many steels. The high strength, hardness, and thermal conductivity of the alloy promotes its use in high load bearings, especially where reliability is required under occasional overload, impact, high temperature, or marginal lubrication conditions. These alloys are used in electrically conducting applications and are frequently specified for aircraft landing gear and other airframe sliding surfaces.<<

So you could be working in the aerospace or electrical industry but so far no help with machining.

From another source:

>>High Copper Alloy. Beryllium Coppers are available in ductile, heat treatable tempers and in mill hardened tempers. Alloys are used in a wide range of applications requiring very high strength and stiffness with good conductivity. C17200 can develop more than 200 ksi (1380 MPa) tensile strength.

Applications Typical uses include electrical/electronic connectors, current-carrying springs, precision screw machined parts, welding electrodes, bearings, plastic molds and corrosion resistant components.

Machinability The machinability rating of this alloy is 20. (Where Alloy 360 FC Brass is 100). <<

I could not find what 100 meant but now we know you could also be in the mould business.

From another source:

>>Machinability
Beryllium copper alloys are readily machinable. In chip making operations, a reduction of 10-25% in machining time, can be seen when compared to tool steels.

Beryllium copper mold materials have hardness properties comparable to tool steels, but with superior thermal conductivity.<<

So obviously it is five times as difficult to machine as brass and up to one quarter easier than tool steel.

And another source:

>>Machinability:

a) Beryllium copper can be machined into intricate shapes.

b) Its machinability in the age hardened condition is comparable to many other copper base alloys,
and better than stainless steels.<<

Many copper based alloys are awful to machine and stainless steels range from fairly good such as the 303, 304 series through to **** awful.

Then from another source which did not exactly have red lights flashing but fairly close!

>>b) Beryllium alloys are very hazardous to your health.

Health Information For Users Of Beryllium Alloys:
Please visit <http://www.ngkberylco.com/safety.html> for significant health safety information<<

This sort of thing could attract your attention and cause a bit of concern so I went further but did not copy everything I read.

Pure Beryllium is definitely not a good thing to inhale or ingest in powdered form but the warning above under b) seems a bit extreme. Below is an abbreviated list of other comments from various sources.

>>Beryllium copper alloys contain very low levels of beryllium - generally between 0.5 and 1.85 percent. These materials pose no threat in solid form.
Beryllium copper in solid form does not emit beryllium "vapors."
Machining coolant does not become a hazardous waste after machining beryllium copper.
Beryllium copper has not been banned in Europe or any other country.<<

So to sum up:

Beryllium copper alloys are going to be similar or slightly easier to machine than tools steels or most stainless steels. My experience with HSS tooling was that speeds had to be down around 100 fpm with several degrees rake on the tool and we used kerosene as a cutting fluid (which was probably way more hazardous to my health than anything from the beryllium in the alloy).

Breathing dust from beryllium, or I would suggest alloys containg beryllium, is not a good idea. But then breathing copper dust is not a good idea so for dry grinding dust extractors on the machines and appropriate breathing protection on the operator is essential.

[ZipSnipe]

Wear a respirator, if your turning it down on the lathe I don't see the potential for dust hazard as a mill would be. Good Luck

[cad01]

are you running on cnc lathe? with coolant? I hope. If so I would run it at 3200rpm, .01-.012ipr, .075doc for rough leaving .01 for finish. run finish pass at .007ipr. for drilling run standard hss drill at around .002-.003ipr with .1-.150 peck. my spindle max is 3200 so I have not pushed it any harder. but you could, if you have higher spindle speeds. As stated before the object is not machinabillity (this stuff is like butter), its about keeping good chips. I use sandvik carbide h13a grade with .016tnr for roughing and .008tnr for finishing. use a positive insert with a good chip breaker.

[ouldeeps]

Thanks for all your help! I only joined yesterday and got all the info in a day! It restores your faith in human nature!
Many thanks again

[Donkey Hotey]

I'll be very interested to hear what you think of it after the job. I'm about to specify some beryllium copper in a design at work and the health hazard is one of the biggest concerns, along with machinability.

Of course, it's awful stuff, but galvanically-speaking, it's an good choice as an intermediate layer between stainless steel and aluminum.