Tap Life

OK, here's a question for all you guru's out there.

I'm tapping 5/8-11 holes, in 4140 annealed, with HSS Steam Oxide coated taps, with coolant. (cnc machine) I need to use a H7 rating, because the bars will be heat treated afterwards. To get any other tap would be 3 weeks out, and I can't wait that long. so I'm married to the above tap.

What type of tool life should I be getting?

atm, I'm getting roughly 250 holes and seeing a nice amount of wear on them.

I'm running the tap 300RPM @ 27.2727 IPM , roughly a 50SFM

Any suggestions on getting a better life out of them?

Reply to
tnik
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Reply to
over a barrel

Why not use a thread mill? You could even cut the threads after heat treat then if you wanted.

Reply to
John R. Carroll

That stuff is great.

Reply to
John R. Carroll

I could thread mill, but no one carries a h7 thread mill in stock. Would be too far out. Plus there are 3,000+ bars to do, each bar with 15 holes.

and they already found out where the holes need to be drilled so their in the right spot after heat treat.

as for using a tapping fluid, I was trying to not have to do that..

So basically you guys are saying that no matter what, to get better life out of my tool, I have to use a tapping fluid/paste..

Reply to
tnik

Sounds like it. You might try messing with the coolant concentration. What are you using?

Reply to
John R. Carroll

Thread mills don't come in H limits, one size fits all. You control size by using cutter comp.

Reply to
Garlicdude

LOL I'd forgotten that, or just didn't know. I've never bought a thread mill by specifying anything but the pitch and sometimes internal/external or both. I'd think a 5/8' diameter would lend itself to an inserted cutter body that would get yuo a range of pitch's with different inserts.

Reply to
John R. Carroll

========= Yes, but the trade off is longer cycle times.

If possible slow the tapping speed down further, and/or add a block where the tap moves over and is dipped into a container of HD tap compound just before it taps every hole. [Remember to turn the coolant off so as not to wash the tap lube off the tap] This may contaminate your coolant if you are running water soluble. It may be possible to use a very "rich" mixture of your current water soluble coolant to eliminate contamination, or at least a water soluble tapping compound to avoid tramp oil.

Some extra heavy duty tapping compounds you may wish to consider are

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401 looks promising.
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Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

Reply to
F. George McDuffee

It's called Blue Cool S2420

and using the recommended concentration 2.5 - 4 from the manufacturer.

Reply to
tnik

========= see

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priced 135 to 362 $US each. Spicy meatball compared to a tap, but....

Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

Reply to
F. George McDuffee

Ahh ok.. didn't know that.. Just knew to get a different coated tap it would be 3 weeks out..

Reply to
tnik

Question:

do you replace your taps before they're expected to break or after they've broken ? how much time do you lose getting them out when they break in the part ?

Reply to
raamman

We are replacing them before they break.. We noticed a nice amount of wear after about 250 holes.. We could probably push it more, just don't want to spend the time getting a broken tap out.

Reply to
tnik

How about regrinding? Properly done the taps will cut H7 for a long time.= Skip the coating and work out a swap arrangement with the tool grinder.

Reply to
J. Nielsen

Very cool!!

I think, tho, solubility with the existing soluble oil may be a double edged sword. Altho a miscible tapping fluid would seem to be an important property in a soluble-oil system, it could, conceivably, detract from the intended properties of the reservoir soluble oil.

Otoh, a tapping fluid non-miscible in soluble oil would by definition not mix, and then could conceivably be recovered by a skimmer, and thus prove to be especially economical.

Just thinking out loud....

Reply to
DrollTroll

Yea, boss doesn't want to go that route.. says it will add too much time to the operation.. well.. that and if the operator isn't watching, KA-POW!!!

Reply to
tnik

thank you for your reply

Reply to
raamman

========= Actually if the container is fixed in place at the corner of the table at about the limits of travel, possible elivated to reduce chips and coolant spray, it is automatic. Simply make a fairly large cup or resoivoir and all the operator needs to do is refill it every few pallets, if you are using a pallet changer. A paint can with a 3/4 hole in the lid works well for this. Insert a few lines of code or call a block to rapid and dip the tap just before every tap operation and be good to go. Thread mill does look like the solution though, if you have helical capability. What's the tool cost per hole, and how much added cycle time?

Anyone got an estimate of how many holes per carbide tap mill? Whats the skinny on resharpening these?

Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

Reply to
F. George McDuffee

Yes even amazing IMO

We have a 1/4-20 in 4130 ~ 42rc that we do regularly and was getting maybe

10 holes with a nice hypro black before the tap would go skreek--now pretty sure its in the hundreds.
Reply to
Bipolar Bear

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