[cm92]

I am new to machining and This is the first time Im trying to mill 420 ss. Most all 6061 before now. I destoyed one hss speed end mill. The part is getting really hot and Im using mist coolant the only thing I have. The chips are still turning colors. What am I doing wrong. I knew that the 420 would be alot harder than the 6061 aluminum but dang this stuff is ruff and all Im trying to mill is a flat .075 deep and about 3" long.

[kweierbach]

I am new to machining and This is the first time Im trying to mill 420 ss. Most all 6061 before now. I destoyed one hss speed end mill. The part is getting really hot and Im using mist coolant the only thing I have. The chips are still turning colors. What am I doing wrong. I knew that the 420 would be alot harder than the 6061 aluminum but dang this stuff is ruff and all Im trying to mill is a flat .075 deep and about 3" long.

cut the spindle speed to around 25-35 sfm and reduce feed rate to find the rpm (sfm X 4 /endmill dia.)
kevin

[Dano523]

If you looking for SS to mill, 440F is the ticket.

Chances are the 420 is not annealed, and the reason that your having a tough time with it.

Machining
420 is machinable in both the hardened and tempered conditions such as drilling, turning and bending. But it is recommended that machining in hardened condition should be avoided.


Edited due to my spell checker blowing big time.

[pete from TN]

haha I am thinking you meant annealed.... or perhaps I am not aware of something in stainless that is actually annulled? peace