What exactly is Rigid tapping? Why people always ask does it do rigid tapping?

[cjchands]

I am in a shop with several CNC Mills and Lathes.
We sold FANUC 6M Drill mate Pratt& whitney and Hundai Fanuc 21T CNC lathe.
People always ask: does it do RIGID tapping??

I searched in the internet and found the definition as:

A rigid tapping cycle synchronizes the machine spindle rotation and feed to match a specific thread pitch!!

My question is: DOESN'T MOST FANUC controller, Haas, Okuma, or major brand HAS "RIGID TAPPING" as standardize?

The only reason that it wouldn't come with Rigid tapping is if you have INVERTER and regular induction motor....ANy COMMENT??????
Thank you.

[toastydeath]

Older machines, and some less expensive/midpriced VMCs do not have rigid tapping. So, no, it isn't standard, and is usually a 1500-2000 dollar option on a lot of machines shops buy in quantity.

Rigid tapping is popular in the industry because there are certain high speed/high performance form taps that will not start in a floating tap holder. You must have a machine that does rigid tapping to use them.

Additionally, higher practical tapping speeds are possible on a rigid tapping cycle. On floating taps, the spindle and Z axes deceleration aren't completely synced, so at higher speeds, the floating tapholder sometimes winds out completely and breaks the tap off. With rigid tapping, the deceleration of the spindle and the Z axis are in sync all the way from full speed to dead stop, keeping the tap from breaking no matter how fast you try to tap.

[aussie28]

I am not a fan of taping on the machine but Rigid taping allow u hold the tap in u er collet same as u end mill. no floating holder require. my understand Rigid taping is u machine motor capable of spining CW and CCW with out any back flashe and synchronized with feed in Z match u input of pitch. Most importance thing is u tap still in one piece after taping cycle.

[Al_The_Man]

Originally Posted by cjchands My question is: DOESN'T MOST FANUC controller, Haas, Okuma, or major brand HAS "RIGID TAPPING" as standardize?.

Not neccesarilly, with Fanuc and some others, the option is in the control but not turned on unless paid for, also the spindle motor has to have feed back encoder on the spindle.

Originally Posted by cjchands The only reason that it wouldn't come with Rigid tapping is if you have INVERTER and regular induction motor....ANy COMMENT??????

With the right inverter/VFD, a regular induction motor can be made suitable for rigid tapping, if a pulse generator is fitted to the motor and an encoder on the spindle shaft.
The method used is called electronic gearing, where the Z axis is electronically geared off the spindle encoder.
This is also required for helical milling.
The similar functions performed on a Lathe would be threading and CSF.
Al.

[Geof]

Originally Posted by Al_The_Man ......The method used is called electronic gearing, where the Z axis is electronically geared off the spindle encoder. This is also required for helical milling.....Al.

Phrased as meekly as possible ...no not needed for helical milling.

Helical milling involves the X, Y and Z axes moving in synchrony but the spindle rpm is not related to any axis movement.

[Al_The_Man]

Geof, My understanding of helical milling is similar to rigid tapping or lathe threading where the Z axis for e.g. would spiral down a bored hole to create a 'Helix'? If so this would require sync to the spindle, no?
I will have to dig out my manual for the canned shape description.
Al.

[Geof]

Originally Posted by Al_The_Man Geof, My understanding of helical milling is similar to rigid tapping or lathe threading where the Z axis for e.g. would spiral down a bored hole to create a 'Helix'? If so this would require sync to the spindle, no? I will have to dig out my manual for the canned shape description. Al.

The Z axis does spiral down, or up, a hole but it is only axis motion involved.

You program a G02/G03 with a Z increment:

G91 G03 I0. J-.5 Z.125 F(something) L10

Will produce an upward moving helix of ten revolutions, actually 1"-8 NC thread with the correct tool. Your spindle rpm is not related to the axis motion.

[Al_The_Man]

I Think I was Probabaly confusing the G33 (constant lead) which I have seen a helix cut with a boring tool.
Al.

[Eurisko]

Geof,

I'm sure you're right, but I still have a hard time wrapping my head around that one. So in thread milling, you could actually press the feed hold button or override the spindle rpms without damaging the thread form?

[cjchands]

So if you were to buy a used CNC VMC or LATHE machine, how would you know or to look for if the machine does or doesn't have RIGID TAPPING function? Check for the encoder on the spindle?

[Caprirs]

Originally Posted by Eurisko Geof, I'm sure you're right, but I still have a hard time wrapping my head around that one. So in thread milling, you could actually press the feed hold button or override the spindle rpms without damaging the thread form?

Yes, that is correct.

Rigid tapping requires an encoder on the spindle (or motor). This allows precise position control of the spindle motor similar to the X, Y, & Z axes. When the rigid tap cycle is commanded, the control changes how it controls the speed of the spindle motor. On such machines, the spindle can be treated like a rotary 4th axis and given specific position commands using G01.

During normal milling/drilling, the spindle is run with the strategy of maintaining rpm while sacrificing "rotation position". During rigid tapping, the strategy is to sacrifice rpm for position accuracy. So, the actual command inside the control typically looks like:

G01 Vv Zz Ff

Thus, the control treats the spindle and Z axis the same way it treats the X & Y axes.

During thread milling, the motion is just a helix with the spindle running at constant speed. The thread precision is controlled by the diameter of the helix (pitch diameter) and the slope of the helix (thread pitch).

[Caprirs]

Originally Posted by cjchands So if you were to buy a used CNC VMC or LATHE machine, how would you know or to look for if the machine does or doesn't have RIGID TAPPING function? Check for the encoder on the spindle?

The encoder indicates the ability to do rigid tapping. However, as mentioned above some older machines have the rigid tapping function as an option that must be enabled by parameter. Most machines have it enabled. The control manufacturer can probably look up the serial number and tell you if the option should be functioning.

If the machine is under power, the easy check is to try the command.