[maximusek]

Hi all,

I used to tap steel 9310 using 8-32NC tap, depth of blind hole 0.3inch, thread .23inch. Since we have changed water based coolant to oil based coolant (prisma 517 Total) I cannot make even one part. Original speed 1832RPM (feed 57.25inch/rev). Today I have tried 1000RPM - tap is dull, 200RPM - tap is destroyed, original speed tap is dull. Of course I adjusted feed to certain speed, even with two pecks - nothing. I have compression holder and still cannot tap those damn holes - what am I doing wrong?? Thank You for any answer..

[G0G90]

Roll tapping (obviously) is a high pressure process.

By changing your coolant, you've lost lubricity for high pressure cutting.
I'd check with your supplier to see if there's an additive available. Otherwise, go back to your water-based (assuming it was synthetic or semi-synthetic)

[maximusek]

Roll tapping (obviously) is a high pressure process.

By changing your coolant, you've lost lubricity for high pressure cutting.
I'd check with your supplier to see if there's an additive available. Otherwise, go back to your water-based (assuming it was synthetic or semi-synthetic)

Well, that I cannot do. The one I was using (Ecocool S761, Fuchs) was killing everything, rust was all over the machine. That is why we have gotten rid of it.
Any suggestion about good cutting oil??

BTW - Thank for an answer G0G90 :cheers:

[G0G90]

I guess first thing, to make certain that it's the coolant and not something else that's throwing you off, try to increase lubricity.
The easiest would be to OP-STOP after the drilling cycle. Grab an eye-dropper of something similar and put some WAY LUBE in your hole. Yes, I said way lube. (it has fantastic high pressure lubrication)
If you're holes are easily tapped, you've identified the source. (coolant)
If you're still having issues ... then we get to go after a bunch of other stuff. Start easy first.

[fizzissist]

I'm just a little surprised you had good results roll forming 9310 with water based.... but if it worked....

For roll forming in steels I generally stopped the machine, blew the water out of the holes, dabbed a little lubricating oil in, and let 'er rip. Roll formers tend to prefer lubricating over cutting oils, unless they're high sulphur/chlorinated..like a good old fashioned screw machine oil.

I'd double check my hole dia, to make sure the drilling hasn't changed somehow. ... and try and get the largest hole you can get away with and meet spec. Otherwise, I'm puzzled why it shouldn't fly.

One MAJOR caveat with converting to oil in a CNC..... your inserts will NOT last as long with oil. I know...first hand.

My first CNC was a 3 axis chucker, and it being an addition to an existing cam-based screw machine shop, we thought we were clever by saving money and not going to water based, and just using the good quality oil we had on hand. Made sense...right?

We were warned....we did not listen, and ended up going to water. Didn't take us long to learn.

If you're having big rust problems, I think you're doing something wrong. Everybody has a little rust of some sort, but not enough to change to oil.

[G0G90]

I'm curious, if you're having issues with rust, why didn't you just add a preventative into your Ecocool?
Who's your supplier - are they helping you with your issues or are you just ordering stuff online (without support)?
For high-pressure applications like roll-tapping, grinding, honing, etc. I've used quite a few different products. Castrol has some decent full-synthetics available but they're a little pricey and you need to watch concentration levels close. Bacteria isn't an issue but mold might. Keep that in mind.
Semi-synthetics might be the way to go. Not overly expensive and offer a good machining range. Foaming was the only issue I had working with many of these. Just be careful with the anti-foamers not to kill the coolant.

After you determine that it's actually the coolant causing your issue, see if you can't get a local supplier to evaluate your needs.

[maximusek]

fizzissist- I came to this company and machines were on the floor set up by somebody; since then water based coolant is used - it's been 6yrs. ago; Who made that decision?? I know as much as you do. I asked one person who was running those machines and he claims than everything was working fine at 1832RPM and F=57.25... Finally oil change, that is not my decision, what I'm doing now is what I always do: asking smarter and more experienced people like you guys, research first...but there are bigger predators in this jungle

G0G90 - rust is a problem but I think they don't want chlorine in it; today me and guy above me spoke with our supplier(Total), we try to go with synthetic oil, so everything you said I'll keep in mind; 10min ago I replaced coolant thru drill, I made 50parts, with Ecocool my tool life was 500, big difference...I prefer to buy more expensive oil and save money on tooling, time to stop the machine and change that tool and make all of the adjustments to bring the part back to normal...
Good idea with test, I'll use Magic Tap tomorrow...

Guys, thanks a lot :cheers: