milling the highest possible finish in copper

[xtd]

We're looking to mill the best posible finish in some small parts. The material is OFE CU ASTM F68 CLS 1. (which is basically the finest grade of oxygen free copper). We need at least a 16 rms or better on the floor and walls of a small iregular pocket. We can't use a wiper type tool because of embedded contaminants as these components are part of linear atomic particle accelerator and must function in ultra high vaccuum. Short of a diamond milling machine (which we don't have) our research has led us to some avenues of approach. I am wondering if they are any other suggestions?

thanks

 

[saberblue]

You might want to try a very high lubricity MQL fluid to reduce the rubbing of the tool on the finished surface -- I understand that you probably should not use fluids with Cl or S in them and what ever the carrier is will need to be washed off easily ---

Here is a link to information of one fluid that might work well - there are of course others this is just one that I am familiar with

http://www.masterchemical.com/inc/pop_doc.php?pid=mql1000&title=TRIM^® MQL™1000&pl=NA

A.R. "Andy" Nelson
Engineering Consultant
anelson@arnengineering.com

 

[MikeHalloran]

Large nose radius.
Fine feed. Super fine feed. Super super fine feed.
Vacuum out the chip continuously.
Small edge radius.
Big, heavy CNC machine.
Stabilize the temperature with a/c and extended run time.
Slow down the axis feeds, and accelerations if you can.
Make parts only in the dead of night, with no other machinery running, and no traffic.
Don't walk, or even talk, near the machine while cutting.





Mike Halloran
Pembroke Pines, FL, USA

 

[SincoTC]

On the few occasions I've had to machine copper, I found ordinary lube oil worked fairly well and I've heard that some even older timers than me, swear that milk (I guess the full fat variety) works even better, although it would need a good clean up after to prevent a stink!!

 

[xtd]

Sabreblue, MQL seems very interesting and you're right, we are very limited in the coolants we can use -no sulfur, no chlorine, no hydrocarbons etc...Right now we are using Trimsol E206 which one of the national labs recommended to us. We have a new Haas VF2 with the air blaster which we might be able to rig up for MQL

Mikehalloran, our pocket floor to wall radius is .000 to .002 max, so a sharp tool is the only way to go. As far as feed is concerned, we are finishing at about .0003 doc @ .0003 ipt. and 420~450 sfpm. We have found that this is nearly the slowest that we can go without burnishing. Vaccuum is a good idea and I have used this method in drilling holes through angled parabolic mirrors, but is also means dry machining which is a little risky for these parts at this time. Interesting also is that we conducted vibrational studies on one of our mills and discovered several frequency zones which produce the most machine movement. We tend to avoid these rpm zones if possible.

SincoTC, I've heard of the milk trick as well. What's more is that I think that I can enlist a squad of local alley cats to clean the machine to maximum cleanliness!


thanks for the feedback!

 

[MikeHalloran]

Use a wet/dry vac and pump the coolant out of it with a Jabsco running slow.





Mike Halloran
Pembroke Pines, FL, USA

 

[KENAT]

No no no, if one cat cuts its tongue on swarf or chips or similar PETA will cause you all kinds of hassle.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[tiehen]

What diameter of tool can be used?

Scott

http://www.1helical.com

 

[xtd]

.25 dia, doc about .4

 

[tiehen]

check out a 1/4" 5-Flute Variable pitch tool w/.020 radius (.500 loc) works very well. Go to

http://www.1helical.com

and download the catalog - go to page 38 and you will see the HEVR-5 Series and the tool diameter/length options. Speed and feed - The key here will be to run a "light"rdoc (.015-.020) with 500 sfm / .0024 clpt to begin with and make sure the tool does not pack-up with chips.

Scott

http://www.1helical.com