Carbide drilling with TSC deep holes

[Stove]

Currently running MITS MVS carbide drills with TSC 1000psi pump on haas vf6ss and having issues with tool life and drills breaking. Drills are being used to drill waterlines in mold bases (typically p-20 material) so depth ranges from 2in to 12in, F&S example for a .343 DIA is 19.5 @ 2200 RPM with SFM @ 195 which gives us a .0045 FPT. This is on the lower end of the range of S&F we have from the manufacture. If we are drilling thru other holes we slow the feed down in about half and that helps along with stepping drills when drilling over 6+ inches so we use a drill up to 6in and then a longer drill past that. Haven't gotten much help from sales rep so curios to hear if other people are having same issues or know of a solution. As far as drilling process its all been done by the manufactures book with the short pilot drill and then bringing in the long drill into the hole slowly then turning on TSC and ramping RPM with a dwell to allow RPM and TSC time to ramp up.

 

[DouglasJRizzo]

Usually, with that style drill, you would "soft start" - in other words, the first 1/4" or so, have a very reduced feedrate, then drill at normal feed, then a "soft exit" where you would reduce feedrate once again as the drill exits the part.
When encountering water lines, and other internal cavities, the "soft start/soft exit" plan would probably help.

I use Kennametal KSEM drills up to about 6" deep in 4140, 4340 and Chrome-Moly all the time with excellent tool life.

 

[Stove]

What would you consider as excellent tool life? I've had a 7/16 drill 8in long drill about 40ft before sending to resharpen. I've also had that same drill chip after 10inches of drilling... am open to new drill suggestions and will have to look into Kennametal.

 

[dandrummerman21]

Are they mostly breaking when a cross hole is existant? I'm not necessarily saying while the cross hole is being broken into, but rather if you've drilled thru one, and start drilling at normal speeds, does it seem to break there more?

If so, I wonder if a chip gets caught between the flutes of the drill and partially inside a cross hole, causing a jam.

What's the tool look like when it breaks (assuming you can get it out). Any chips or wear on the cutting edge? If it looks really nice, I would suggest its a chip evacuation issue of some sort.

Last thing I would suggest, maybe stick with cobalt/hss for the long drills. Yes it will take longer, but what do your drills cost? couple hundred bucks?

 

[Stove]

Are they mostly breaking when a cross hole is existant? I'm not necessarily saying while the cross hole is being broken into, but rather if you've drilled thru one, and start drilling at normal speeds, does it seem to break there more?

If so, I wonder if a chip gets caught between the flutes of the drill and partially inside a cross hole, causing a jam.

What's the tool look like when it breaks (assuming you can get it out). Any chips or wear on the cutting edge? If it looks really nice, I would suggest its a chip evacuation issue of some sort.

Last thing I would suggest, maybe stick with cobalt/hss for the long drills. Yes it will take longer, but what do your drills cost? couple hundred bucks?

I've had 2 break in the plate while drilling a normal hole, no cross hole, just drilling 6in and made it about 4in into it and snapped in half... nothing left of them after having to hammer them out with a chisel. Other drills have chipped right at the center point of the drill like when it started the whole it hit something. because of that we have been checking every hole for chips before drilling and making sure its a clean entry. going through holes typically has a couple crunching of chips in cross hole but once a little past it smooths out and the chips actually exit through the cross holes along with some of the collant from the TSC

 

[TeachMePlease]

Mits are waaaaay high up there on drill quality...

What's your runout look like?

 

[Stove]

Mits are waaaaay high up there on drill quality...

What's your runout look like?

.001 to .002 on the 12in long drills

 

[BT Fabrication]

whats the alignment of the machine like?

 

[Stove]

whats the alignment of the machine like?

just checked it last week and everything was good. machine is only 6 months old

 

[Mr.Chipeater]

.001 to .002 on the 12in long drills

What kind of holder? Also, any chance of the TSC dropping pressure causing a momentary drop in coolant flow? The TSC unit on our UMC gives us lots of headaches and we seem to get much better TSC drill tool life on our 30 year old Mori.

 

[Stove]

What kind of holder? Also, any chance of the TSC dropping pressure causing a momentary drop in coolant flow? The TSC unit on our UMC gives us lots of headaches and we seem to get much better TSC drill tool life on our 30 year old Mori.

Redline collet holders, tsc pressure seems consistent through out the cycle. but would be nice if the pump wasnt regulated as much so we could have more pressure on the deep holes, example would be the 7/16 drill has a max psi of 550 based on how that pump is programmed

 

[Ni200]

What are you doing in the very beginning? How are you spotting the hole and creating the bushing for the longer drills to enter?

I'm sure you know, any drifting will cause a carbide drill to just simply break. Also, just to be sure, you are not pecking correct?

Are you spot/using a stub drill to at least 2xD and reaming/boring a bushing to encompass 1 full helix of a flute, and then using the extra long drill?

 

[Stove]

What are you doing in the very beginning? How are you spotting the hole and creating the bushing for the longer drills to enter?

I'm sure you know, any drifting will cause a carbide drill to just simply break. Also, just to be sure, you are not pecking correct?

Are you spot/using a stub drill to at least 2xD and reaming/boring a bushing to encompass 1 full helix of a flute, and then using the extra long drill?

Using a short pilot drill to start the hole that is same size as the drill we are gonna use for the hole. Pilots are nice and leave a machines like finish on the walls so don’t see that being an issue.

Anything past 6in we are peaking. Manufacturer said the drills are capable of it and is necessary to clear chips because there isn’t enough psi from the pump to clear chips in those deeper holes or if there is a cross hole

 

[Ni200]

Using a short pilot drill to start the hole that is same size as the drill we are gonna use for the hole. Pilots are nice and leave a machines like finish on the walls so don’t see that being an issue.

Anything past 6in we are peaking. Manufacturer said the drills are capable of it and is necessary to clear chips because there isn’t enough psi from the pump to clear chips in those deeper holes or if there is a cross hole

That may start to cause a lot of problems with the drill rapiding back down crushing any breakaway chips, as well as the RPM/TSC creating a wobble effect on the exit, then chipping the ends of the flutes on reentry. Do you 5% rapid once the drill begins the pecking? You maybe getting chips packing into those waterlines and once the drill rapids back into the hole re-engages the hardened chips while moving too quickly thus your breaking issues.

Have you just tried to drill all the way without pecking? Since your breaking drill anyways it may be beneficial to give it a go and see if you can find goldilocks zone of feed/speed where you do not need to peck at all.

Also what does your pecking depth look like? I don't use TSC and regularly drill X15-20D holes in high temp alloys for thermocouples and typically use the 3-2-1-.5D reduction rule, they are not carbide drill, but I can drill those all day with no trouble.

 

[Stove]

That may start to cause a lot of problems with the drill rapiding back down crushing any breakaway chips, as well as the RPM/TSC creating a wobble effect on the exit, then chipping the ends of the flutes on reentry. Do you 5% rapid once the drill begins the pecking? You maybe getting chips packing into those waterlines and once the drill rapids back into the hole re-engages the hardened chips while moving too quickly thus your breaking issues.

Have you just tried to drill all the way without pecking? Since your breaking drill anyways it may be beneficial to give it a go and see if you can find goldilocks zone of feed/speed where you do not need to peck at all.

Also what does your pecking depth look like? I don't use TSC and regularly drill X15-20D holes in high temp alloys for thermocouples and typically use the 3-2-1-.5D reduction rule, they are not carbide drill, but I can drill those all day with no trouble.

Drill never leaves the hole when peaking just comes up to where it starts in the pilot hole. When there is a cross hole chips are pushed out from the tsc so everything is clear and sounds good like no chips are being caught. Have tried drilling all the way only to e stop the machine because the flutes filled with chips and and would have broke the drill. Pecking at 1x Dia.

Both times the drills broke was mid way through drilling cycle going down 6in they just snapped around the 3-4in mark. No through holes no chip overload nothing that would cause that to be reasonable and drills were fairly new and checked constantly because weve had issues and are new to tsc drilling with carbide

 

[BT Fabrication]

what coolant and typical concentration is running in the machine?

 

[Stove]

what coolant and typical concentration is running in the machine?

Metalworks trim coolant mixed with water and is at 7 on the refracter

 

[dandrummerman21]

Might not be the exact cause of anything, but a couple things to adjust or change:

1: make sure the tip of the long drill is the same or smaller than the pilot drill. If the long drill is 135, the short drill should be 135 or 140.

2: make sure that the return distance in your drilling canned cycle is not very small. No idea what the setting would be on a haas, but you don't want it to rapid back down to .005" above the last depth it reached. Maybe .020" to give any possible remaining chips time to move. There shouldn't be chips with the coolant thru, but just an idea.

3: slow your rapids down for retracts, or hardcode pecks so your retracts are more gentle. I've seen suggestions before of people making their own macro g-code for their own peck cycle. Ideally, you would want to feed the drill up a few thousanths at a modest feedrate before rapid up to clear chips. I don't know if your haas' canned cycles have any provision for that or if you would have to do it yourself.


These might not solve it but you could look into it.

 

[Archer120x]

Why are you pecking? With TSC, I don't peck.

 

[thedude31]

I would check your coolant pressure. you should not have any issues at those speeds. I use to work in mold a few years back and would use the same type of drills. I would normally start a hole with a stub carbide drill (same tip angle) going as deep as .250 then chase it with a 8 inch mits and one shotting the hole to 7inches. I would reduce the rpm and feed when entering the hole and stop about .1 above ramp up dwell a few seconds and let it rip. This was done in a Matsuura Mx 520 with great coolant pressure.

I forgot to mention I was drilling h13 and 1 drill would handle 80 holes (46ft in depth) before replacing.