Adaptive and breaking end mills

[leo.castellon]

 I have a major problem here and I can't figure out why I keep breaking end mills in the same spot. Please see attached files. I am roughing out a block of 17-4 Cond A material with a Helical endmill. I have broken 2 end mills at exactly the same spot. I thought perhaps the first time that maybe I didn't have the ER-32 collet tight enough so I switched to a heat shrink holder and it broke the 2nd end mill at the same spot. I am machining the outside profile in 2 Z steps, ironically, the first Z step machines fine. I am getting really nice chips, no noise and low load on the spindle meter. I can't keep scrapping expensive end mills and material and I need to get these parts delivered Friday. 

I would appreciate any help, thanks.

LeoC

[a.laasW8M6T]

idk, all your feeds n speeds look good, as do all the other cutting parameters. the toolpath looks fine too.

The only thing I can think is maybe the part is moving in the vice?

17-4 in condition a is pretty ****ty to machine but I've not had troubles like that before

[mattdlr89]

Is this a rapid issue? The Haas will dogleg rapid by default. Looking at your file it, is doing rapid moves below the top of the material so simulation will not be accurate in the rapid moves to what could be happening at your control.

There's a few ways to get around this:

1. In linking tab: Change the "High feedrate Mode" to "preserve single axis rapid" or "always high feed"
2. In linking tab: Change retraction to "full retraction

3. At machine: Change setting 335 on your machine to linear rapid mode.

You should only need to do one of the above to fix it so the choice is yours (if that is actually the issue).

[CRANDALLPRECISION]

Take a look at this. added a toolpath

[leo.castellon]

Thanks for the replies. I have used this toolpath numerous times without any issues so it was rather unsettling to scrap tools and material on this job. I have the adaptive tool path saved out as a template and have used this on numerous 17-4 parts, so I am confused why I was having problems all of a sudden. I also use this path on only one machine here as it has a geared head and has a bit more torque, so the machine settings never change. 

What I ended up doing is as suggested and that was use full retraction. Also, the first Z step is now .1 stock to leave and the 2nd Z step is .150, that way, if the end mill for some reason hits the side wall during retraction or in an X, Y move and breaks the end mill, I should still have some material left to remove the crash mark by using the contour operation. It is much cheaper to run more contour operations to get the part to size than experiment more with different settings in adaptive. Also, the part did not lift out of the vise as I ran an indicator across the machined face and it was still Zero. 

Thanks, LeoC

[leo.castellon · Accepted solution]

Just an update, used a different end mill and the attached file purrs like a kitten with the parameters as set, end mill was a Helical 34302, run on a Haas VF2 with a short heat shrink holder. Material is 17-4 Cond A, fun stuff.

I also increased the lead in and out to .2 from my previous file. 

Cheers, LeoC