Odd endmill break

[plastikdreams]

Had a .625 5 flute low helix carbide endmill snap like I've never seen before. Aluminum 100 ipm 12000 rpm .4375 doc .38 width. The carnage on the actual cutter is from the end launching around the inside of the machine. Anyone seen a break like that?

 

[Finegrain]

Is it coated, TiAlN or AlTiN? If so, maybe it loaded up suddenly and then there's a huge side force?

Regards.

Mike

 

[Bill D]

Right at the top of the flutes. I assume the flute ends is a stress riser. Was the break well below the collet?
Seems like it would shear in the flutes since that has less material to break.
Bill D

 

[BoxcarPete]

That's a crack propagation fracture. See the half moon shape extending most of the way across? Once the crack worked its way across the diameter, the rest of it just gave up all at once. The sudden jump in stiffness can act like a stress concentrator right there where the flutes end, because that section of the endmill will be stiffer and resist deflecting much more than the fluted part. Must have been a microscopic flaw somewhere in there that grew in the shear plane until the whole shank just snapped.

 

[Rickyb]

I tend to agree with Pete. I say tend to because the pic if the fracture face is a complete blurr and a fracture running 3/4 through a brittle material before final failure is highly unusual.
If this is a hss blank with a carbide flutted end welded on, then all makes sense. You have a failure at the joint.

 

[plastikdreams]

Solid carbide endmill brand new TiAlN, broke right at the opening of the side lock holder. Tool was cutting fine, hardly any noise then pop...no aluminum in the flutes when I grabbed it. No cutter fragments embedded in the aluminum.

Grabbed a similar endmill and finished the job...milled off 19x20x1.315 of material exact same cutting conditions.

I'm thinking there was a flaw in the carbide. Usually they just explode, never seen a .625 cutter slice like that.

 

[Milland]

I'd offer to send it to the cutter manufacturer in exchange for a replacement. They should be interested in seeing the failed tool to try to find the root cause, especially if it might be a batch issue.

 

[plastikdreams]

I'd offer to send it to the cutter manufacturer in exchange for a replacement. They should be interested in seeing the failed tool to try to find the root cause, especially if it might be a batch issue.

Eh it was a nos cutter I got from shop supply Guru last year. I think it was a gorilla mill.

 

[eKretz]

Yeah that's an awfully straight shear line, haven't seen that before.

 

[DavidScott]

Yeah, several times. It was with DataFlutes right after VR Wesson bought them. I would say it's bad carbide.

 

[plastikdreams]

Yeah, like I said, .625 endmills don't just up and snap like that lol. Thanks for the replies so far!

Filled up a 55 gallon drum with nice big chips lol...I haven't made a mess like that since I was job shoppin back in the day.

 

[richard newman]

Eh it was a nos cutter I got from shop supply Guru last year. I think it was a gorilla mill.

Could still send it to them, nothing to lose

 

[plastikdreams]

Could still send it to them, nothing to lose

We'll see

On another note I'm still not sure why shop supply Guru got the ban from here, he had great deals that really helped a lot of people out.

 

[BT Fabrication]

Yeah that's an awfully straight shear line, haven't seen that before.

seen that a few times unfourtnately,

flutes bind up only at the bottom, shears all the flutes off on the bottom 1/4 and breaks it clean off at the base of the holder. machine doesn't stop when it breaks, keeps shoving it sideways.