"Randy" wrote in message ...
RE. my last post on buying carbide end mills.

THe job I was doing when I killed the two 3/4" x 2.25" LOC carbide
ends mills was milling a slot in 17-4PH annealed stainless. About 32
Rockwell C. First end mill was run at S651 F4.67 really badly chipped
after first piece.

Second one was run at S300 F3.10 I got throught 1/2 a slot when I got
a X-axis overload. It had started to pull the part up out of the vise
and was cutting in deeper.

Finished that part and the last one with a HSS end mill, uncoated, at
S212 F1.49 and it worked nicely, but alittle slow.

Job is done, but why was I killing end mills? First end mill was run
at speed and feed I found for a carbide finish end mill. Second F&S
was from a table in an OSG book for carbide roughers.

4" round bar clamped tight as hell in a kurt vise with 3" tall jaws.


Remove 333 to reply

Your surface speed was way too slow, suggest next time start around 180 sfm and work upwards from there.

As a point of refrence, I use to mill that stuff in the annealed condition pretty without coolant much all day long on a bridgeport hand mill at a speed where chips just barely begin to turn a light amber color.

Avoid re-cutting of chips like the plague.

Other caveat being it will work harden in a heartbeat if you're not paying attention and so if it starts into skreeking at you then PULL OUT FAST