455 stainless turning on swiss machine

[ChristianK]

stainless guys,

I always work on titanium so stainless is quite a change for me. The best part is not worrying about major fires all the time. The bad part is this stainless just seems to love wrapping up around itself and the part. I have high-pressure coolant, two turning tools pinching and a subspindle holding the other end of the part. Without the subspindle there the part would bend/whip/fly off ruining all my tools and possibly the machine. Now my question is...how can I get the chips to break?

I'm currently using a ECAS-20 swiss machine with two seco DMCT TS2000 55 degree .016 CR turning tools pinching 0.375 OD bar to 0.226. Finish must be great and tolerance is plus or minus 0.001. Now I'm running awesome (tolerance / finish wise) parts but op stopping the machine after every turn gets really annoying.

I've ran so many types of feeds/speeds. No difference. Also have tried cutting then retracting to break chip then cutting again. Seems to make a little difference but not enough. Besides making a tool with a Y in it to rub the part and then retract the bar to pull the chips off I have no other ideas.

Any other suggestions?

[tobyaxis]

Rats Nests are the number one reason why we swiss guys hate stainless. I have had the same problem with Inconel X750, 316L, 316, 321 or any stringy nickle based material.

The only thing you can try is to take short light cuts and get the string of the chip to direct into the chip pan. Being that your balance turning and using the sub for a stabilizer one tool is cutting up, the other cutting down.

I wish there was a better way myself.

Do you have a Turret on your machine, or Gang Tooling??

[ChristianK]

Gang tooling. I wonder if I only used one tool on the down facing gang it would work better. Problem with that is tool life. Just finished one PQ...part spec and finish were great till the end :P but it worked. Still op stopping the machine all the time really sucks. Light cuts are pretty much out of the question as it would take longer than op stopping. Turned shaft is 8" long.

I agree with you, swiss + stainless really sucks on real turning applications.

[tobyaxis]

Originally Posted by ChristianK Gang tooling. I wonder if I only used one tool on the down facing gang it would work better. Problem with that is tool life. Just finished one PQ...part spec and finish were great till the end :P but it worked. Still op stopping the machine all the time really sucks. Light cuts are pretty much out of the question as it would take longer than op stopping. Turned shaft is 8" long. I agree with you, swiss + stainless really sucks on real turning applications.

It pretty much sucks turning stainless period. On a standard lathe you can take rough cuts with a nice chip breaker style insert, but on swiss you have to rough and finish in the same cut. That is our problem.

Do you have any live tooling attachments??

You might be able to engage an End Mill to Combo Mill/Turn and Balance Turn all at the same time.

8" shafts should really be Ground to size first so you don't have to turn the O.D. Then do all the Secondary Bores-C/B's, Grooves, Threads, U-Cuts, on the ground to finished O.D. bar stock.

Do you have any other dimensions you can share for this part??

[dudesmpd]

I turn H13 tool steel that gave me the same headaches
what i ended up doing was using a Kyocera DCMT32.52gk- grade 5525
6000rpm and .008 feed
holds a good finish and chips well with high pressure coolant.
Its always a good idea to call tech support for the insert manu. for ideas too

[ChristianK]

it isn't just a shaft...its a custom driver for our custom screws i can't give much information now as we're not open and all of these are PQ lots.

mainly there is a hex in the front, long shaft which comes to a radiused head and then backturned behind that for an inch and a half. now burrs are no problem usually but this part i need to knurl for an inch with a tolerance on the knurl itself plus or minus .002. one chip and the knurl isn't good.

get my frustrations? :P