Tormach 770 Modular Mill Surface finish

[legacymachining]

Hi Folks,

Tormach 770, using the module 25mm endmill with tormach steel cutting inserts. I am working on dialing the program in for surface finish with poor results. I seem to have chatter maybe? it sounds ok when cutting, loud but no squealing. A-2 material, .060" DOC, .1" stepover, 1600 RPM, 18 IPM. Image attached, Thoughts?

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[tmarks11]

Can you physically feel any of those marks? If you drag your fingernail across the workpiece, can you feel any ridges?

[SCzEngrgGroup]

If you want a good surface finish, you would normally do a very shallow finish cut - typically no more than 0.005-0.010 DOC". You should likely also be feeding faster on the finish cut, to compensate for chip thinning. Assuming it's a 2-insert tool, 0.01" DOC, 0.1" WOC, I'd be running ~1300 RPM, 44 IPM. Are you using coolant? If not, you really should be. If so, what kind - flood? mist?

I find I get a really nice finish on most metals using HSM techniques - narrow WOC (usually ~0.05", and high speed). I would try 0.05" WOC, 1300 RPM, 60 IPM, using a Facing operation and only climb-cutting. This should give a good finish even with your 0.06" DOC. You MUST have coolant to do this.

Regards,
Ray L.

[legacymachining]

Yes you can for sure feel them. Its a 3 insert cutting tool. using flood coolant. i was hoping to reduce the cycle time, but i guess it beats hand lapping. 2d adaptive toolpath, ill give a finish pass a shot. thanks guys

[SCzEngrgGroup]

Yes you can for sure feel them. Its a 3 insert cutting tool. using flood coolant. i was hoping to reduce the cycle time, but i guess it beats hand lapping. 2d adaptive toolpath, ill give a finish pass a shot. thanks guys

Adaptive is not always the best for finishing - it's really intended for fast roughing. With 3 inserts, and 0.050" WOC, you should be able to run almost 90 IPM using a constant-engagement facing toolpath, and get a lovely finish.

Regards,
Ray L.