Rigid Tapping Struggles
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    Default Rigid Tapping Struggles

    Hey all,

    Let me preface this by saying that I am not a rookie. Ive been machining for 10 years and run a shop.

    I'm having trouble breaking taps!

    Last week I broke a 1/2-13 tap in some O2 Tool steel on the last hole, last peck! Well I blame that on the tool steel and nothing else.

    Howver, Ive been breaking far more taps than usual lately, specifically in aluminum. Currently on a new Hurco VM10i machine, running about 800-1200 RPM for aluminum. First question, is that way too fast for general usage? I ask because I have successfully tapped many 1/4-20 holes running 2000rpm in the past. Sometimes I peck tap, sometimes not, depending on the hole. I leave plenty of clearance below the tap point if it is a blind hole.

    Ive been running mostly spiral flute taps for chip clearance. Kennametal taps (kinda shitty), as well as Widia and some Emuge. Well in the past I have used OSG taps for steel alot and those things are amazing. Should I consider changing back to OSG taps? Some of my taps are uncoated, some are TiN or ZrN coated. Should I stick to uncoated?

    Anyone have a rigid tapping recipe that just works? And what brands of taps are best for aluminum? Cost of the taps is not an issue but I would prefer not to have to get into carbide.

    Also, I form tap for my smaller holes. Should I just suck it up and get forming taps across all sizes?

    THANKS!

    -cm

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    Quote Originally Posted by metalmadness View Post
    Hey all,

    Let me preface this by saying that I am not a rookie. Ive been machining for 10 years and run a shop.

    I'm having trouble breaking taps!

    Last week I broke a 1/2-13 tap in some O2 Tool steel on the last hole, last peck! Well I blame that on the tool steel and nothing else.

    Howver, Ive been breaking far more taps than usual lately, specifically in aluminum. Currently on a new Hurco VM10i machine, running about 800-1200 RPM for aluminum. First question, is that way too fast for general usage? I ask because I have successfully tapped many 1/4-20 holes running 2000rpm in the past. Sometimes I peck tap, sometimes not, depending on the hole. I leave plenty of clearance below the tap point if it is a blind hole.

    Ive been running mostly spiral flute taps for chip clearance. Kennametal taps (kinda shitty), as well as Widia and some Emuge. Well in the past I have used OSG taps for steel alot and those things are amazing. Should I consider changing back to OSG taps? Some of my taps are uncoated, some are TiN or ZrN coated. Should I stick to uncoated?

    Anyone have a rigid tapping recipe that just works? And what brands of taps are best for aluminum? Cost of the taps is not an issue but I would prefer not to have to get into carbide.

    Also, I form tap for my smaller holes. Should I just suck it up and get forming taps across all sizes?

    THANKS!

    -cm
    i usually only run 300 rpm when rigid tapping, and my peck is set at 1xpitch...
    just switch to form tapping and your problems will be solved. lol

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    Quote Originally Posted by Diezel View Post
    i usually only run 300 rpm when rigid tapping, and my peck is set at 1xpitch...
    You must have some really long cycle times.

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    Yeah, get some more form taps, but also try to confirm that the servos 'n stuff for Z are working correctly so you're not losing rotary/linear coordination. Or get a tapping tension-compression holder for a little extra "give" in case there is error in the electronics.

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    Form taps

    I would fall asleep at 300 rpm

    I would slow down tho, until I stop breaking things

    I break taps when the drill breaks and tap goes into a non hole, pretty much never any other time

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    Quote Originally Posted by gustafson View Post
    I break taps when the drill breaks and tap goes into a non hole, pretty much never any other time
    Tool breakage detection FTW.

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    A couple of things here that I see.

    Generally when tapping, I start the tap at least .25 away from the part surface or more, giving the machine time to accelerate and get the torque up. Tapping o2, I would keep the tap speed around 150 to 250 RPM depending on what the manufacturer says. One thing about rigid tapping, at the higher speeds the tap will never fully reach that speed before having to reverse and back out. This is why the load meter slaps the redline like it does. If you're using rigid tap, I would think slowing down a bit would greatly increase tap life.

    For tapping aluminum, I would max it at about 500 RPM unless you've got a tap that the manufacturer says can go more. Tapping is a severe operation and I'm leery of cranking rpms on it.

    Another point - I generally tap in IPR mode rather than IPM for a few reasons. It gives more accurate control and if you need to make a speed change, the thread lead follows automatically.

    Coolant is one more area. I'm testing various coolants now, but lubricity is very important. When tapping tough stuff, I keep a tube of Castrol tap wax nearby as well.

    Just my 2c..

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    I form tap anything below 1/4" unless there are special considerations. 2,000 RPM for anything below 1/4" (actually 4,000 RPM for production). AFAICR, I've broken exactly 1 tap in 4.5 years in my VMC, where I had no idea why it broke. I have broken a few taps for apparent reasons like not-a-hole, or grabbed an NF tap instead of NC.

    I've run several form tap brands including Kennametal and Balax, and am now migrating to Guhring. No specific reason why, I just like them better.

    Cut taps, when I use them, are Accupro. Again, no specific reason, just they seem to work well.

    Regards.

    Mike

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    Can't believe these low speeds for aluminum, 2000 rpm is our shop standard up to 1/4-20 smooth as silk on a Fadal.
    For tool steel the only advise is thread mill or Blitz tapping clutch in tension/compression holder, but they don't peck.

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    Check your coolant.

    I have a lightweight machine (Haas super mini mill), but I run straight oil, not coolant. I have never broken a tap, and have form tapped and cut tap up to about the limits of the machine's power in aluminum and steel.

    I understand that virtually nobody is going to run straight oil, but point being... lubricity is really important, as DouglasJRizzo said.

    Oh... one other thing: how are you holding the taps? ER collet made for taps? Something else?

    PM

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    Hmm lots of interesting tips here.

    I think I will invest in some more form taps. Most of my tapping is 1/4 and below anyways. I doubt that there is software/hardware issues with this machine as it is 3 years old and is not running in production, it is a prototyping shop with small batches and is not running all the time. Also, most of the tap breakage is with spiral flute. If i run a straight flute tap even in a blind hole, it seems fine for some reason. IDK why.

    I hear conflicting reports on spindle speed. Some say don't exceed 500, some say run it fast. Historically I don't break alot of taps, but in the past month it has been more frequent as I have been getting new brands of taps.

    As far as coolant is concerned, I am running Blaser Synergy 735 around 6-7%. I sometimes use Tap Magic on steel.

    Generally, my feed plane for all drilling is 0.1 inches, so I can start doing higher feed planes to see if that helps.

    -cm

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    Get the best tap you can. OSG has always been good to me. Be sure it's the correct coating for your material.
    Coolant/lubricant and tap coating can make a big difference.
    I form tap aluminum from 1000 to 6000 rpm, depending on the size of thread. 6mm is usually 4K rpm, 5mm is 6k, just because (it's a Brother, what can I say ). I use a form tap, either coated or uncoated, but make sure it has the proper coating. Some coatings don't work as well in aluminum as others. I use Hocut for coolant. Did some 1/2-13 holes 5" deep form tapping, did a peck every inch to make sure coolant was in there, and it was a short job. I normally don't peck form tapping, just make sure there's a lot of coolant on the job.
    Even my old super minimill tapped well at 1500 rpm.

    If your torque curve isn't in the right place, running too slow might be worse than running faster.

    Good luck!

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    If you're running too fast you'll get shortened tool life, not breakage.

    Also, I would way rather use coolant-fed form taps than peck tapping. Peck tapping is for the birds, no pun intended.

    Quote Originally Posted by eaglemike View Post
    Get the best tap you can. OSG has always been good to me. Be sure it's the correct coating for your material.
    Coolant/lubricant and tap coating can make a big difference.
    I form tap aluminum from 1000 to 6000 rpm, depending on the size of thread. 6mm is usually 4K rpm, 5mm is 6k, just because (it's a Brother, what can I say ). I use a form tap, either coated or uncoated, but make sure it has the proper coating. Some coatings don't work as well in aluminum as others. I use Hocut for coolant. Did some 1/2-13 holes 5" deep form tapping, did a peck every inch to make sure coolant was in there, and it was a short job. I normally don't peck form tapping, just make sure there's a lot of coolant on the job.
    Even my old super minimill tapped well at 1500 rpm.

    If your torque curve isn't in the right place, running too slow might be worse than running faster.

    Good luck!
    You haven't lived until you've watched a Brother tap.

    It's like a power riveter.

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    Quote Originally Posted by metalmadness View Post
    I think I will invest in some more form taps. Most of my tapping is 1/4 and below anyways.
    Yes, do this! Just be aware that hole size is way more important with form taps than with cut taps.

    Guhring has a really nice form tap hole size chart on their website, which I have printed and taped to the wall by my workstation:

    Tapping Drill Size For Thread Forming - GUHRING

    Yes, .001" on the hole size can make a big difference in form tap results. I aim for 67.5%.

    Regards.

    Mike

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    I mostly run YG1 taps and 250C coolant between 7 and 9% mix ,, on aluminum I run non coated only and even 3/8-16 I run at 4K down and up, the only time I slow down is if I am doing a blind hole I have found I need to let the coolant have time to get out of the hole.

    I run some blind hole parts with 1/2-20 ans have found I get chips washed down in the bottom of the hole and if I set my clearance plane at 1" above it gives the coolant time to flush the chips out. my normal clearance is .2 off the part on smaller holes ,,

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    +1 on coolant and coating compatability. Breaking taps primarily in aluminium is indicative of chip welding. Make sure your taps are suitable for aluminium, and make sure your coolant works well in aluminium for high pressure applications.

    I use Hysol XF in our machines because we machine a lot of different materials and it works well in most of them, however it sucks at high pressure applications in aluminium - milling al. is fine, tapping it sucks and turning it sucks, lots of build up on the tool. I keep some neat Hysol in a bottle and use it for tapping, but I don't worry about the speed I'm tapping at, use whatever is the appropriate surface speed for the size of the tap. Many times the machine won't ever reach that speed anyway, but it's never a problem.

    Roll taps are great in aluminium but make sure they are uncoated and polished unless you have some magic coolant that completely negates build up in aluminium.

    I also have Hurcos and there is a rigid tapping monitor somewhere in the integrator support section that displays realtime servo-spindle sync latency during rigid tapping. I have never had to use it so I can't help with that, but it's there.

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    Quote Originally Posted by mhajicek View Post
    Tool breakage detection FTW.
    Well, you go hop in the time machine and whack me in the head before I order this machine....

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    Quote Originally Posted by gustafson View Post
    Well, you go hop in the time machine and whack me in the head before I order this machine....
    A BK Mikro setup is pretty inexpensive and easy to add to most machines that don't have a toolsetter, but you still obviously have to be able to justify it with unattended operation or a lot of holes, etc.

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    Quote Originally Posted by Rick Finsta View Post
    A BK Mikro setup is pretty inexpensive and easy to add to most machines that don't have a toolsetter, but you still obviously have to be able to justify it with unattended operation or a lot of holes, etc.
    WE could also program the machine to stop after the drill has drilled dunno 50k holes and change it........

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    Quote Originally Posted by gregormarwick View Post
    +1 on coolant and coating compatability. Breaking taps primarily in aluminium is indicative of chip welding. Make sure your taps are suitable for aluminium, and make sure your coolant works well in aluminium for high pressure applications.

    I use Hysol XF in our machines because we machine a lot of different materials and it works well in most of them, however it sucks at high pressure applications in aluminium - milling al. is fine, tapping it sucks and turning it sucks, lots of build up on the tool. I keep some neat Hysol in a bottle and use it for tapping, but I don't worry about the speed I'm tapping at, use whatever is the appropriate surface speed for the size of the tap. Many times the machine won't ever reach that speed anyway, but it's never a problem.

    Roll taps are great in aluminium but make sure they are uncoated and polished unless you have some magic coolant that completely negates build up in aluminium.

    I also have Hurcos and there is a rigid tapping monitor somewhere in the integrator support section that displays realtime servo-spindle sync latency during rigid tapping. I have never had to use it so I can't help with that, but it's there.

    Soooooo what kind of coatings do you recommend for aluminum? Guhring has an insane amount of coating options, so I don't even know where to begin


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