Fanuc G84 tapping = tool comes down to work, feeds in at rate calculated to be correct lead for RPM, spindle reverses and tool comes back out.
Fanuc G84 Rigid Tapping = tool comes down to work, spindle stops and orients itself, feeds down, spindle stops(dwell can be programmed: why?), spindle reverses and tool feeds out. Retract rate can be set by parameter to be as much as 4x the infeed.
For general tapping (a number of average, meaning no more than 3x tap dia, thru holes or blind holes with plenty of room for chips) what would be the advantage of one cycle over the other?
G84 tapping requires a compression/extension holder. Rigid tapping can use a standard ER collet holder. G84 tapping requires a higher clearance height usually.
BTW, rigid tapping and synchronous tapping are synonymous.
The advantage for 3x the pull out is to reduce cycle time. I can't think of an advantage to dwelling at the bottom of a thread. Maybe to reduce heat before pulling it out at 3x the infeed. Fanuc also has a peck cycle for rigid tapping as well. Pretty cool to watch.
4x outfeed = each tapping cycle takes only 1/2 as long when compared to compression...often this effects a very significant rate increase--esp. where there are many holes to be tapped per pallet laod ( as in multi parts-high density fixturing ).
I wonder if the outfeed is adjustable on a Haas VMC this way. I've not noticed it just skimming through the parmeters. I use it every time I tap on my Mazak M-Plus mill (H300 =300%). We've got a large lot of simple tapped blocks comming up on the Haas.
Actually, there can be several advantages to using synchronous or rigid tapping. How much of an advantage you get depends a lot on the machine, and also on HOW the tapping is accomplished. Here's some real basic stuff, to start with.
Real "Synchronous Tapping" isn't really synonymous with "Rigid Tapping". In rigid tapping, used by most controls, the infeed (usually Z axis) is kept timed to the revolution of the spindle. This eliminates the need for tension/compression tap holders, and can often create better and more accurate threads because there's no axial spring pressure on the tap. That pressure can make for slightly distended thread forms in soft materials, and can tear the first thread at the top of a hole when the tap is pulled by the holder as it exits. Tap life can also suffer as a result of rubbing on the thread flanks caused by the spring pressure.
Syncronous tapping, first used (to the best of my knowledge) by Brother, is fundamentally different. Instead of keeping infeed timed to spindle revs (one is independent, the other is not), real synch tapping is actually a genuine linear interpolation between Z and the spindle. This is typically only possible with smaller machines that don't have real massive spindles, and which can use something very much like an ordinary servo motor to run the spindle. But the difference is dramatic.
With real synch tapping, just like with any other linear interpolation, the two axes match speed perfectly (including accel and decel features), and both get to the programmed endpoint at the same instant. The interpolation is almost as good as what you get from X/Y moves, except that the spindle accuracy isn't improved by the mechanical advantage of a ballscrew. But the two axes stay in synch at ANY speed! There's no possibility of "overshoot" when you get to the bottom of a hole. When Z decelerates and stops at the programmed depth, S does exactly the same thing.
With "Rigid Tapping" of the most common kinds, S still has to declerate (slowly, clumsily) after the hole depth has been reached. Z follows along, of course, so you can get similar (though often smaller) overshoot to what you'd expect from a tension/compression holder. Better systems will look ahead, and will decelerate S a bit early; but it's still a very approximate thing - heavily influenced by workpiece material, and by how quickly tapping torque will bring the spindle to a stop. The real depth of a hole won't be exactly what's programmed unless you're turning the spindle very, very slowly.
And that's the main functional difference - the part about turning slowly. With real synch tapping, you can tap as fast as you like, and still get excellent results. When interpolating with, say, X and Y, you just naturally expect everything to work perfectly no matter how fast or slow the table is moving (unless you're working at extreme speeds). With synch tapping, you enjoy the same kind of accuracy and reliability. So, you can run ANY tap at speeds and feeds that are right for the tool and material, and not limited by the machine. 50 SFM for a 10-32 tap would be 1020 RPM and
31.875 IPM infeed. And, if your machine has the accelerated retract feature, you might back out of the hole at over 4000 RPM and over 100 IPM on Z. And you'd do all that with complete confidence that the tap stopped right where it belonged, instead of running into the bottom of the hole and turning to powder.
With rigid tapping (as on a Fanuc control), you get somewhat better speed and control, significantly better holes, and probably better tap life. With real synch tapping, you can get MUCH better speed, perfect depth control, and all the advantages of quality and tool life, too.
I first got my hands on a Brother TC-211 tapping center in early 1985 (the first one in the US); and I've absolutely hated spring tap holders from the moment I tapped my first hole on that unique little machine. Fanuc, and everybody else, has offered "rigid tapping" for a long time, as a way to compete with the real tapping centers; but it just isn't the same thing. It's good. It's better than plain old G84, But it's a long way from really, truly making a tap behave like it should.
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