Microdrilling

[danrudolph]

I've been working on several small Ti parts with 10xD holes between .0200 and .0255. I've got prototype parts made, but the drilling cycle is too conservative.

I see there being 3 main variables: feed rate (.0001/rev), peck depth (.002), spindle/live tool speed. I am limited to 8000 RPM on main and 4500 RPM on my live drill. I am at the low end of the SFM from the mfg recommendation of 80.

What is the best approach to improving the drill cycle?

[UK-Engineer]

Depending on your machine and cost you might want to go down route of high frequency spindles from the likes of Ibag.

http://www.ibagnorthamerica.com/pdfs...e-Brochure.pdf

thanks

[SwissType1]

depending on the make and model of your machine, Genswiss may have a high speed attachment that will help get your SFM where it needs to be.

www.genswiss.com/swissmachines.htm

[HSPMInc]

I have a similar part out of Ti that has an .028 hole in it. I run it at 3500 rpm, .0005 in/rev of feed and .01 drill pecks. Works like a champ, and I get great life out of the drills.

[danrudolph]

Thanks for the info. We are looking at adding an NSK or IBAG spindle as soon as possible.

For those of you that use high speed spindles, do you run them at full speed or throttle them down to hit a precise SFM? Is there a down side to running at full speed?

[UK-Engineer]

"For those of you that use high speed spindles, do you run them at full speed or throttle them down to hit a precise SFM? Is there a down side to running at full speed?"

Hi,

The Ibag models i use include a speed regulator up to maximum of 80,000 rpm so you could regulate speed in line with correct cutting speed. I have one job running where we don't exceed 50,000 rpm and we've had pretty much faultless reliability

I'd imagine the downside to running at full speed would be the same as anything else with issues like bearing life wear etc probably being proportional to the speed you run at - speak to their technical people who'll know best.

Anyway good luck with the Ibag/ NSK option - I've not used NSK recently but the Ibag is a good product

[danrudolph]

Update:

We purchased an NSK 24,000 RPM air spindle for the A20. We knew this would solve the problem but it was $2,000 we were trying not to spend. But now, we are running the main spindle a 4k and the NSK at 24k. We dropped the drilling cycle time by half, increasing the feed and peck distance. ROI on the spindle will be about a week.

The parts look amazing and done in 2/3's the time. The fixed length from the guidebushing that the geared live tool gave us was too much and we were getting .0015 to .002" runout on our parts.

Only thing left to do is use an M code to turn the air spindle off and on.

Thanks!

[ProProcess]

Originally Posted by danrudolph ...Only thing left to do is use an M code to turn the air spindle off and on. ...

If you have a High Pressure Coolant Pump, you are likely not using the Air Blow option for the Knock-Out.

We route our NSK Air spindles through the Knock-Out Air Blast solenoid and control it programmaticlly with M72/M73.

Good luck!

[danrudolph]

Thanks for the tip. However, we are using only the air blast for part ejection. The parts we make have a very thin walls (.002") and some have an angled face which has to be free of knicks. So we can not use the knockout device and are forced to use air only.

We have 5 M codes available to use, so it's just a matter of getting a solenoid and tying it in.