Has anyone experienced a Brand new End mill failing after 10-20 min of normal use, cause I just had 2 fail on me…
what material?
Can be bad feed rate, trying to remove too much material at once, or improper lube…
I am with @Kevin_Osborn : Aren’t you moving it faster than the bit is cutting?
BTW, lube, such as when cutting aluminum, is mostly about controlling heat. If heat from friction gets too high, tools lose their temper or hardness and become dull very quickly. I’m not an expert on this, but I gather that this is another factor in selecting feed rate and RPM, as those factors also control how fast heat is created or dissipated.
Also you might be driving it too slow… here is a good source to figure out feed rate and RPM or if RPM is fixed figure the feed rate. link -> https://www.youtube.com/watch?v=ip2jm_6aUyk
I am cutting wood, at 400 mmpm, at 30000rpm, well with in the feeds and speeds of the manufacturer. This was a titanium coated carbide end mill.
Also the other end mill from the same company worked great until someone crashed it. All at the same feeds and speeds I am using now.
What’s the cut depth? And what type of wood?
1mm per pass, black walnut, the same end mill from the same manufacturer, worked until someone broke it, with all the same feeds and speeds with no issues, well except for the crash.
Have you checked the polarity of the spindle (if it’s DC)? My end mill broke a flute when I ran it backwords on oak.
Yup, my spindle is an Dremel, so no polarity issues there.
What size of end mill?
1/16" square end 1/2" flute length, 1" reach 1/8" Shank 2.5" over all length.
I think that’s your problem. That’s a long skinny bit, and your step down is over 60% of your bit diameter. And black walnut is a hard material. There’s a lot of flex being put on the bit. I’d drop down to .5mm step down or even less. I think you’re going to continue to break those bits at your current settings. With a 1/16 bit I only do 1mm step down in soft materials like balsa or plastic, and those bits only have 1/4" to 3/8" flute length. If it worked for a while I don’t know how. Maybe you were just lucky.
that is possible, but it worked not just for a while for probably a good 48 hours of use on the bit through black walnut as well as mahogany, Oh well the end mills are now useless and I have another on the way.
They do break occasionally, even when used properly. I always order a few extra just in case.
Yeah, just odd that it was 2 in the same hour…oh well it happens. Got 2 more on the way.
Are these import discount cutters? Maybe you are getting inconsistent quality. Look at the new ones you get under a microscope. If you still have the good one you broke, compare to that.
Nope they are from Harvey Tool in Mass. at 35$ a pop.