Need Help!- Are all small end mills carbide?

[Micro Milling]

Was looking for some 1/32 or .020" to .050" end mills and have noticed they are all in carbide. Thought I would go cheap and get some HSS ones.

Is there a reason for this? I heard carbide needs high RPM, will that matter in my mini-mill with max of about 2500 RPM?

ALso a side question, will the cobalt M2AL end mills work fine with lower RPM? I can pick those up cheap, so thought I would get those instead of HSS.

[serriadh]

If you're using very small end mills you'll need high speed regardless of the material. At 2500rpm, a 1/32" end mill will be moving its flutes at something like 20 feet per minute, if my maths hasn't deserted me entirely.

(1/32" * pi = 0.098" circumference * 2500 rpm / 12" = 20.45)

Google for recommended surface speeds. One source suggests 50fpm for steel, and 250 fpm for aluminium... thats 6100 and 30500rpm respectively! You're not going to get a good surface finish or tool life at only 2500rpm, regardless of what the bit is made of.

[RICHARD ZASTROW]

You might try investigating HSS single lip end mills and engraving tools. Company I worked for used them to mill small features in dies. Down to .007" Rad. @ 40,000 rpm. Worked fine.

Dick Z