Drilling on Haas...

This is for my curiosity, I ran into a problem today with one of our machines. We are running a part right now that we are drilling a hole all the way through, please for give me for not knowing the drill size, but we check the hole to see if it is the correct size by using Gage pins.

We use a 0.387 pin for the low tolerance, if it goes all the way through it is correct, and if the Gage pin of 0.392 does not fit all the way through thin it is at the high tolerance. We had one or two parts that the gage pin went straight through. Not one after the other but about 1 in every 20 parts, why is that? I know I am not explaining this the best but just curious!

The parts are copper, and they are sitting against a fixture.

Are you torquing the vise?

Yes it is, and it is copper

Chips getting stuck on the drill? How deep is the hole?

Wow, so much information missing to answer that question.

- Which copper alloy?
- Spot drilling?
- Drill - Actual size, material, tip grind, coolant through?
- Feeds, speeds, coolant, etc
- Depth of hole (material thickness, if through)
- Gauge pins for a drilled hole? You have a 0.005" window there, while a drill is usually a roughing tool.
- Part holding details could be critical too

Maybe some of this won't matter after others are answered, but really? You need to give specifics when you ask a question like this.

^^^^ what was said......
Which copper and hardness?
unless it's a wide open tolerance, drilling to finish size can be iffy. Spotting helps a lot. Drill type and condition can make or break the process... Speed and feed, and coolant also affect things.
The fact that it's a Haas machine is most likely not important.....
(IMHO)

I do know we are not using a center drill before we drill the hole, I will get all of those questions answered tomorrow when I go in and ask the Program writer

crb06 said:

I do know we are not using a center drill before we drill the hole, I will get all of those questions answered tomorrow when I go in and ask the Program writer

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It's great that you're really digging in and trying to learn all of this, but watch out for guys that think you might be "pestering" them with questions. Some of them may even start getting defensive because they think you're questioning their knowledge and or skill at doing their job. Insecurity even in grown men is commonplace. This can put you in a very bad position in very little time.

I hate to even mention it because I don't want to deter you from seeking out knowledge on your own, but there is a time for quietly watching and learning as well. Sometimes all you can do is point out what you think might be a problem and listen to what your more experienced co-workers have to say without adding much yourself. Then you find out the most likely "true" answer on your own, but you also keep that information to yourself for now. In time, you'll know enough that you won't have to ask and you can quickly spot the inevitable BS you'll get from others.

crb06 said:

Not one after the other but about 1 in every 20 parts

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hy crb i would definetly consider it luck with high probability, and i would go gambling : roulete, casino, national lotery, etc

... at least i would now that is me beeing lucky

but i doubt the a normal human has 5% chance of luck ... but maybe you are in that tiny class

good luck

I think your problem is... COPPER!
I had a similar problem just yesterday... 7.5mm drill followed by a 8mm reamer.

First part came out great and in spec. Next part sounded funky when the reamer went in so I stopped it to check. The finish inside the hole looked more like a rough tapped finish from the drill in some spots... Yup the hole was not round!

Make sure that your drill is running nice and true in the holder (I use ER collets). Then reduce the feed on your drill about 10-15% (15 was the sweet spot for me). Try not to full retract peck and if it isn't too deep don't peck at all so that the chip comes out nicely up the flutes of the drill. If any of the copper gets stuck on the drill you are going to get the size messing you around. Mine was 4xD so I pecked 4 times and it seemed to break the chip off nicely and away from the hole without full retract between pecks (my particular machine that I was using for these parts is setup to only retract 0.1mm per peck with G73). I used a plain old HSS drill as short as I could hold it in my collet and the same with a HSS reamer but not too short as not to get coolant down the hole while in operation. I cannot exaggerate this enough... Blast the crap out of it with coolant right to or as close as possible to where it's drilling.

For future reference I landed up reducing my reaming feed 20% as well and my holes were in spec. The rest of my run of parts came out great. Good luck!

It's because a chip got stuck in the drill flutes or in the hole. Its not rocket surgery.

Thank you everyone for your reply's! I asked the programmer and he said the same thing as all of you, that the chips could be getting stuck in the flutes of the drill, he told me as well that if the drill was getting dull that the holes would be undersized....

crb06 said:

Thank you everyone for your reply's! I asked the programmer and he said the same thing as all of you, that the chips could be getting stuck in the flutes of the drill, he told me as well that if the drill was getting dull that the holes would be undersized....

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.
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material sticks to cutting edge its called false cutting edge. when cutting edges are uneven drill tip wanders cutting hole bigger. as picture shows drill lost one flute cutting edge and the .409 drill drilled closer to .450 dia holes 11 times and did not break.

crb06 said:

the programmer ... said the same thing as all of you

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maybe one of these answers is from your programmer

NAST555 said:

I think your problem is... COPPER!

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You nailed it. 'Cause all copper "alloys" machine the same...

[Edit: Some may not catch the sarcasm here, but it is definitely present.]

We ended up just replacing the drill with a 25/64th drill