A similar question came up here on CNCzone in 2005 but I do not know how to find the post I did at the time so here it is repeated.(Obviously it was closer to the end of the year. )
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:
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:
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.