Machine Tapping

Oh, heck. They also list aluminum on their chart at 90-100. Now I am really confused.

At 95 that comes out as 6.175. That makes more sense, but then it becomes a problem to turn that slow and still apply full power with most machines guys like me can afford.

And why do they list aluminum at 90-100 and many of the milling sites list aluminum from 500 to as much as 1200?

I had thought up until this moment SFM was SFM.

It all depends on the tap I would say.. If its a standard HSS tap with no coatings, we normally run them at 100 RPM with oil in steels, and coolant in plastic or aluminium. If we get into some type of production, then we look at better taps so we can get faster feedrates.

We tend not to push a tap too hard, because it is normally a final operation, and its a bitch to drill them out if they break.

??

Maybe the operation does matter.

I totally hosed that one hey Tim. LOL.

I run pretty conservative numbers to make sure my customers have reliability and efficiency.

Generally, I run taps at 1/3 the drilling RPM and plan on needing 200% of the HP requirement for drilling. ...Cut tap, HSS.

I use the following chart to estimate those numbers:

Thanks, Joe. You those are going in the binder I keep out in the shop.

Man, I have a radial arm drill and a heavy duty CNC mill and i only go about 1/3 of these numbers. IMHO, a typical HSM ain't got a chance with light equipment at these speeds. Keep in mind these numbers are for production shops.

Just my 2 cents

Karl

Karl is mostly right here when it comes to RPM. The charts are conservative in some respects (lower RPM than some achieve with the same HSS tooling) but they do presume proper coolant, sharp tooling, rigid set-up, etc.

The numbers work just fine for me on my cheapo drill presseses here in the shop, but I'm very careful to always use lubrication such as cutting oil, etc.

As for the feed rate... Most people can't "program" their feed rate so it's not a huge issue. with almost all materials, a lesser feed rate won't do much harm. In stainless, the exact opposite is true. A lesser feed rate causes more heat build up and that is a very bad thing in stainless.

Overall, on a manaully fed drill press with some sort of cutting fluid to cool the drill, the numbers on that chart should be safe for just about everything you do.

Obviously, I do it in a NON home shop enviroment, but in aluminum....6061, for example, I'll run at between 600 and 800 RPM with flood water soluble coolant.

For a REAL production run....a few thousand holes, I'll set up the reversing tapping head on the VMC and spin that at about 2500 RPM

But that is just me....your mileage may vary

Mike

A Fanuc Robodrill (CAT 40 VMC) will peck tap 1/4-20 UNC holes at 10,000 RPM. That's not just me. Your mileage won't vary.

That would necessitate some pretty fast reversals, no?

I don't doubt that at all...I am, however, using a fairly old Hurco that couldn't spin that fast with a bullet at the set-up dudes head....that's me, by the way.

And the reason for the 2500 speed is that that is all the faster the head is rated at. I have a smaller one that I use for taps #10 and under that will take up to 4500.

Mike

At 10,000 RPM, a 20 TPI tap would travel 8.33 inches per second.

At 2,500 RPM, 2.08 inches per second.

And real "look ahead" on the part of the control. The decade three Fanuc controls have a real kinematics model integrated into them. You definitely want to bolt these things to the floor. Depending on the model, they will feed as fast as 4,000 IPM. The spindles are an integral design and all of the communication is through fiber optic cables. Don't miss an opportunity to see one running in a shop that knows what they are up to.

What is really interesting about these things is the amount of processing that is done on the drives. The feed back loop is only marginally closed.

Yea, these production guys live in a whole 'nuther world.

All my CNC tapping is at 100 RPM and that's plenty fast. For the one of jobs I do increasing tap speed from 100 to 10,000 RPM would save a couple minutes out of my day. And maybe not that, I use machine run time to set up the next op or clean the shop. Or if its a long program, start making parts on another machine.

Anyway, if you can do something else while your machine runs; speed is not an issue for us HSM types. Now breaking a tap in a part IS.

Again, just my two cents. I go slow and try real hard not to f*ck up and break s*it. Takes less effort in the long run.

Karl

I feel the same, yet, the production world is fascinating.

John R. Carroll wrote in rec.crafts.metalworking on Wed, 15 Dec 2010 17:11:57 -0800:

At work we just got two new robodrills. Smaller than CAT 40. And boy can it move. It was tapping some small parts so fast, you couldn't see the spindle stop and reverse. If tapping blind holes with a roll (forming) tap, you have to go slow to give the coolant a chance to escape. The thing sounds like a dental drill when milling.

I've seen these walk a long way (relatively) in as little as a single shift.

Or use taps relieved for this purpose. They have a small (0.020") hole through the center of them. The hole is made with a wire that gets disolved out at the end of the manufacturing process. You might want to pass that along.

Something else. Measure the thread depth between holes. Your jaw will drop when you see how close thay are to being identical.

I hear that. Lately my jobs all take hours and even days rather than minutes. I spent the last week designing and building 3 unique parts for somebody else and modifying one somebody else made for them so it would actually work. My anxiety level has been above my eyebrows. If it was not for having to stop and watch the machines run and go take care of my clients at my day job I don't think I'ld have relaxed at all. LOL. It's one of the most fun week I have had in a long time.