carbide drill not wearing well

[HEAVY METAL]

i using an sgs 103 series carbide drill 31/64 dia. 4140 pre-hard is the material i'm machining.

drill depth 1.0 thru no peck. sgs book says 115 sfm .003 per rev. (for tool steel 40 rc and below) this is a 3 flute drill. drill did about a 100 holes then started making some serious noise. the tip seemed to be discolored like it was getting hot. should i try peck drilling . i thought this carbide drill would hold up alot better. the feed per tooth seems conservative enough maybe to slow but that is what book recs.

any have any thoughts on this problem

 

 

thanks heavy

[Bruce Caulley]

The material sounds like it might be more than 40rc. Through coolant? If not I would give g83 or equivalent a try.

 

HTH Bruce

[Psychomill]

I'm thinking a series 103 is not the best choice. I use it in aluminum a lot but thats about it. Try a series 135. Good finish, good hole size, good wear. Sounds more like you're sticking, causing heat

 

[medaq]

Check run out on the tool?

 

Jim

[Mike Whitten CAD/CAM Contractors]

Heavy,

 

quote:

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drill did about a 100 holes

---

This does not sound all that bad to me. Consider just sharpening the drills and run em!

 

Thanks,

Mike

[cblythe3d]

Don,t drill thru for best drill life with SC drills. As the corner breaks down, a heavy work hardened burr is formed, leading to accelerated decrepatude. Pull it out of the hole just before completion then break thru with a stub cobalt. This works especially well for 3 flute high feed drills.

[crazy^millman]

I would not spot or center drill with this drill takes aways something like 60% of the life. I would look to thru the tool coolant and as little as peck as possible if you have this capabilities.

 

JYJ

[robk]

I would not peck with solid carbide drill. Definitely no spot drilling (unless your spot drill has the same tip angle). Is the drill coated? If so you need to recoat it after re-sharpening. If you're going too slow than you'll burn it up... 100 holes @ 1" deep is not acceptable. I do have 3 flute drills in here, but always had better luck with 2 flute.

[CNCme]

Good Day,

 

+1 Cbly

 

The break-thru on hard matl. will destroy most

drills...If anything peck the last break-thru @

small amounts.

In my case, I drill for endmill entry, so a minimal break-thru will do it, so an endmill

will not to have to centercut break-thru.

 

 

Tony G

CNCiT Precision Machine - Hudson,NH

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Almost Employed Senior Programmer

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[jeff]

If you must break thru,the thing I found works best is slowing the rpm's down and increasing the feed just before the full dia breaks thru.

this works especially well with hss/super cobalt spade drills on a lathe.

 

Have you ever tried the ChamDrill Jet drills from Iscar?

Very very good.

Mitsubishi,Tungalloy and OSG are the only 3 brands of solid carbide drills I buy.

[HEAVY METAL]

yea im not to happy with these drills. tried some T-A drills and they seem to do better . this is with their tin coated insert not carbide.