Accordion Chip When Drilling

T

T_Dubs

Plastic

Joined

Jan 17, 2020

• Mar 21, 2021

• #1

New here, new to CNC. Just trying to learn stuff.

Never seen this before but also haven't ever used a 3 flute drill. I didn't figure it should matter much.

Drilling .322" hole is titanium. Using a Guhring 3 flute carbide drill, 80 SFM, 8IPM feed, comes out to .0084 per rev, .0028 per tooth. Is that too fast? Seems super slow, but haven't done much with titanium.

Thoughts on feed or speed?

Thanks,

 

TeachMePlease

Diamond

Joined

Feb 11, 2014

Location

FL

• Mar 22, 2021

• #2

What kind of Titanium? That makes a big difference. Depending on your coolant situation, 80SFM is in the ballpark, you can get up to 120ish if you've got great coolant delivery and/or high pressure coolant (in Ti6Al4V). You could up the feed some, to try to break that chip. But I've never run a drill that big in Ti, all my stuff is tiny, so that's just a gut feeling.

 

J

josephk

Aluminum

Joined

May 16, 2018

Location

Hudson Valley NY

• Mar 22, 2021

• #3

I had the same chip when drilling thru 3/4" set-screws(C45) with a 3/8" carbide drill, 2 flutes, no TSC,
116 SFM, .0035 IPR,

 

Last edited: Mar 22, 2021

M

metalmadness

Hot Rolled

Joined

Nov 25, 2015

• Mar 22, 2021

• #4

+1 on feed rate increase, need to break the chip

 

T

T_Dubs

Plastic

Joined

Jan 17, 2020

• Mar 22, 2021

• #5

It is 6Al4V.

I'll try increasing the feed a little, but I'm already passed the "recommended" feed from guhring.

I also don't know if there is any harm in it as it runs now. Time will tell if I lose a drill every 10 holes or something. The long chip isn't a huge deal as I'm only drilling .850 deep.

 

T

T_Dubs

Plastic

Joined

Jan 17, 2020

• Mar 22, 2021

• #6

Minor update. I increased the feed t 10 and 12 IPM with no real change. At 12 IPM, the chips came out a much darker color so obviously getting much hotter. When the drill bit retracts, it is smoking and bubbling coolant off of it. I think I'll slow the feed to try to make the drill bit last a little longer. I think the problem is I can't get coolant down in the hole to cool it while it is cutting.

As for the chips, I think it is just a result of the drill bit. It isn't split point and without a pilot, I think that is just what I'm going to get. Once I break/toast these, I'll look for something better that will cut better.

Thanks for the help!!

 

litlerob1

Diamond

Joined

Nov 4, 2013

Location

Utah, USA

• Mar 23, 2021

• #7

Maintain the same time feed, but slow down your Spindle.

R

 

Matt_Maguire

Stainless

Joined

Oct 17, 2011

Location

West-Central Illinois, USA

• Mar 23, 2021

• #8

Which titanium? I have HSS drill recipes from 100sfpm down to 15sfpm with feeds from .003”ipt down to .0015”ipt? You can do the 3-5X speed up-bump with carbide, not sure about the feed though.

I swear I’ve never seen a drill chip flowed & folded back on itself like that either … What does the break out side look like?

Good luck,
Matt

 

Mike1974

Diamond

Joined

Nov 5, 2014

Location

Tampa area

• Mar 23, 2021

• #9

TeachMePlease said:

What kind of Titanium? That makes a big difference. Depending on your coolant situation, 80SFM is in the ballpark, you can get up to 120ish if you've got great coolant delivery and/or high pressure coolant (in Ti6Al4V). You could up the feed some, to try to break that chip. But I've never run a drill that big in Ti, all my stuff is tiny, so that's just a gut feeling.

Click to expand...

<disclaimer>
I don't know shit about titanium, but that chip looks like too slow feed to me...

(carry on)

 

T

T_Dubs

Plastic

Joined

Jan 17, 2020

• Mar 25, 2021

• #10

I think it has to be the drill. It cuts good and leaves great surface finish from start to finish, clean exit, no burr or anything. I've ordered a different drill from Maritool to try just for the heck of it, or in case these 2 break or something.

I've tried 40-100 SFM and .001-.005 feed per tooth all with the same type of chip. Not sure if its a bad thing, but on the higher feeds, the drill was smoking hot bubbling coolant as it went back into the tool changer.