HSS Drill in 1144 "Stressproof" S/F - Page 3

# Thread: HSS Drill in 1144 "Stressproof" S/F

1. Originally Posted by G00 Proto
I wonder if something isn't messed up on the bar ends. Gotta figure the way Stressproof is made that the very end of the bar would have very different characteristics than the rest of the bar. An easy check would be to cutoff a couple of inches from the leading end of the bar... but I realize you Swiss guys like to set up a dozen bars then come back a couple days later and pick up your paycheck

Ha! Yeah, tomorrow I will do some math to see if the drills really ARE failing near the beginning of a new bar or if I am just making that up. It should be easy to add the amount faced and cutoff to the length of the part and divide to figure out how many parts I get per bar, etc. and go from there. Again, I would think that maybe not turning or cutoff but that .130" wide end mill would be blowing up as often at the drill if the problem was material-related. (that's a .130 wide slot with radiused corners X .090" deep in one pass, FYI)

2. Originally Posted by Nerdlinger
Ha! Yeah, tomorrow I will do some math to see if the drills really ARE failing near the beginning of a new bar or if I am just making that up. It should be easy to add the amount faced and cutoff to the length of the part and divide to figure out how many parts I get per bar, etc. and go from there. Again, I would think that maybe not turning or cutoff but that .130" wide end mill would be blowing up as often at the drill if the problem was material-related. (that's a .130 wide slot with radiused corners X .090" deep in one pass, FYI)
Not if the problem areas are located along the centerline of the bar. Would also explain how hardness tests don’t pick it up

3. I tried increasing the feed. See the attached pic for the various chips formed with their respective various feed rates. Do those look like proper 1144 chips to you? The little crumblies on the bottom of each grouping were found inside the part after I pulled the part out of the sub spindle after cutoff. I do not know if those are left from drilling (maybe the follow up countersink?) or if they made their way in there from some other op. To me they all look about the same, just thicker with the higher feed rates.

Today I broke a second cobalt drill at 200 pcs but it literally broke drilling the first hole after auto bar change! I found the slug that was cut off and it looked fine, facing and chamfering looked fine, so I have NO idea what could go wrong there BUT at the same time the coincidence is too....coincidental....to ignore, IMO. SO maybe something weird is happening mechanically during a bar change or maybe there is something different about the bars at the ends but tomorrow I should be able to force an auto bar change and see if I can reproduce the failure. Fingers crossed, haha!

4. SND
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Is that material ground, with ends squared and chamfered, or is it just regular bar stock that tends to have crappy tapered ends?

5. Originally Posted by Nerdlinger
Hi Rick!

This whole debacle started with my assumption that I "should" be able to get several hundreds of 1.5X deep holes in 1144 with a plain old HSS drill but after trying several different cutting parameters to no avail I am about to order a "real" drill and that will be an Iscar Sumo-Cham. It might be overkill but I'm hoping that a double-margin carbide insert drill with 1,000psi going through the tool will be able to put this to bed. If that still doesn't work I will try other drills I am unfamiliar with like the one you suggested. Thanks!
Sumitomo makes the kind of drill I'm talking about; someone else mentioned it as well. It just has the corners clipped like a corner chamfer end mill does, and I've used them followed by a flat bottom drill or for through holes in a few applications where we were blowing the corners off drills. The geometry looked identical to the other drills we've used form Sumitomo but I can't recall what series they were; I will try to remember to ask my tooling guy next time I see him.

6. Originally Posted by SND
Is that material ground, with ends squared and chamfered, or is it just regular bar stock that tends to have crappy tapered ends?
It’s just regular CD. I think the ends are sheared. I still have the slug from the fresh cutoff I can measure to see if it’s round.

7. Are you sure it's Stressproof? 1144 is just an alloy, whereas Stressproof is a specific drawing and heat-treating process, starting with 1144.

My experience with both is that Stressproof machines a lot nicer than 1144. Also (I have no specific data to back this up), I would expect that LaSalle is going to be pretty careful about the metallurgy of the 1144 they use to make Stressproof, whereas workaday 1144 might have wider variances in alloy constituents, and could be all over the place WRT to heat treat and temper.

Regards.

Mike

8. Originally Posted by Finegrain
Are you sure it's Stressproof? 1144 is just an alloy, whereas Stressproof is a specific drawing and heat-treating process, starting with 1144.
I agree with Mike, BTDT. If you just call for 1144 you're not, in my experience, going to automatically get Stressproof. You may get 1144 Class A which while still being 1144 is not Stressproof or equiv.

What do your MTR's say, OP?

9. Sure is a stubborn problem Nerdlinger...

Took a look at post #11, the (drill) makers advice for dropping sfpm would be correct → if it’s carbon or low alloy speed goes from 80sfpm @ 100bhn all the way down to 30sfpm @ 425bhn. Resulphurized and leaded don’t have a speed bump until you get to 275+bhn. The bright drills are usually M1,2 or 10 & all are fine for 1144.

Took a look at posts #25 & #29 → some folks say LaSalle “stressproof” has a sweet or pleasant smell when you turn it (lotta HR low alloys get similar comments cutting through the bark). Your chips look like your cutting with oil, 1144 chips for no reason.

Anyway, I’m attaching from Republic steel, Metcut & Moline tool (the famous “hole-hog”). The Republic is for screw machine-heads, the Metcut & Moline are for hole-hogs & natco’s that multi-spindle drill through bushings (bushings help the drill a crap ton). The moline also has drill thrust forces in their charts (118° chisel point type circa the 1940’s).

I would also like to know if lilrob has a constant going on that I missed in Special Ed one day (post #30 → .406x.0156x2=.0126), Moline does show 1/2” going near there for feedrate though...

Good luck
Matt

10. Originally Posted by Matt_Maguire
I would also like to know if lilrob has a constant going on that I missed in Special Ed one day (post #30 → .406x.0156x2=.0126), Moline does show 1/2” going near there for feedrate though...
Matt
My Grandpappy told my Daddy who told my Brother who told me. 1/64 per diameter per flute. Bigger Drills take a huge amount of abuse, so the bigger the Drill the greater the chipload. That's actually where I got the information though, it's not just as farce. Grandpa was Machining pre 1940's. So a lot of torque, not like the tinker toys we screw around with these days.

R

Almost forgot to add, if you want to get an almost exact match to manufacturers recommendations, you need to subtract the width of the Web (chisel point of the Drill).

11. Hot Rolled
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Originally Posted by Nerdlinger
Today I broke a second cobalt drill at 200 pcs but it literally broke drilling the first hole after auto bar change! I found the slug that was cut off and it looked fine, facing and chamfering looked fine, so I have NO idea what could go wrong there BUT at the same time the coincidence is too....coincidental....to ignore, IMO. SO maybe something weird is happening mechanically during a bar change or maybe there is something different about the bars at the ends but tomorrow I should be able to force an auto bar change and see if I can reproduce the failure. Fingers crossed, haha!

material settling/shifting in clamp with force from drilling? my guess, sticking to it for right now.

12. I have always found the 1100 series steels to seem to be more abbrassive, and will wear out tools much quicker than say the 1200 series.
(1100 series is basically a "feee machining" series IMO, so I compare to 1200 as opposed to 1000)

M42 usually holds up MUCH better than M2.
ESPECIALLY in custom ground form drills!

I've never experienced any issues with bar ends being harder that I can think of, and I Shirley wouldn't expect actual LaSalle products to be that way.
(Stress and Fatigue Proof)

I would play with the bar change routine and see if there is some oddity there.
Are you fluent with this lathe and bar feeder? Or fairly new to it?

I didn't catch what size bar you are running?
I have 5000# of well seasoned and certed 9/16 hex that I would like to move some day....
(Not sure without looking if it's Fatigue or Stress)

------------------------

Think Snow Eh!
Ox

13. There's still a "top cut" operation (or should be). I don't understand how the feeder could cause the bar to be harder than when it gets loaded. Especially in the centre of the bar.

14. Originally Posted by Nerdlinger
I tried increasing the feed. See the attached pic for the various chips formed with their respective various feed rates. Do those look like proper 1144 chips to you? The little crumblies on the bottom of each grouping were found inside the part after I pulled the part out of the sub spindle after cutoff. I do not know if those are left from drilling (maybe the follow up countersink?) or if they made their way in there from some other op. To me they all look about the same, just thicker with the higher feed rates.

Today I broke a second cobalt drill at 200 pcs but it literally broke drilling the first hole after auto bar change! I found the slug that was cut off and it looked fine, facing and chamfering looked fine, so I have NO idea what could go wrong there BUT at the same time the coincidence is too....coincidental....to ignore, IMO. SO maybe something weird is happening mechanically during a bar change or maybe there is something different about the bars at the ends but tomorrow I should be able to force an auto bar change and see if I can reproduce the failure. Fingers crossed, haha!

If the bars have sheared ends, that could be work hardening them just enough to damage the outer tips and you maybe get a few more parts then failure. This has enough carbon to get pretty hard especially when sheared after stress relief.
Try cutting all sheared ends off before loading bars (or add a parting off cycle to new bar ends), that is just a good practice anyway with sheared stock, as the ends are distorted by shearing.
(On edit, Just re read #46, “slug from cutoff” so does that mean you are doing that already? If so, never mind!)

15. Titanium
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Originally Posted by Nerdlinger
can I get 500+ holes out of a regular HSS drill in 1144
Maybe not?

I haven't read this whole thread. I realize you want the most holes as possible but I've been thinking 200 .406" holes 1/2" deep out of a HSS drill is that so awful?

If you don't know how get a cheap drill grinder, tune up the drill occasionally, preferably before it looks melted. I think this should help get more parts out of each drill. They start to squalling or raising hell I'll take a peek at it then tune it up if it needs it, should be able to use each drill until they get short and need pitched in the can..

Like I say I ain't read all of this someone may have already mentioned this? Good luck

Brent
Last edited by yardbird; 10-02-2019 at 01:17 AM. Reason: Edited post

16. Originally Posted by yardbird
Maybe not?

I haven't read this whole thread. I realize you want the most holes as possible but I've been thinking 200 .406" holes 1/2" deep out of a HSS drill is that so awful?

If you don't know how get a cheap drill grinder, tune up the drill occasionally, preferably before it looks melted. I think this should help get more parts out of each drill. They start to squalling or raising hell I'll take a peek at it then tune it up if it needs it, should be able to use each drill for quite a while.

Like I say I ain't read all of this someone may have already mentioned this? Good luck

Brent
Mat'l was not 1144, it was 4140 PH (I think*), but I counted over 600 holes with a Guhring coated (not sure, been some years) 3/8-16 tap. Maybe just switching to a good brand HSS coated drill might up the number of parts.

17. Hi guys,

After loading a new bar it cuts off the first inch or so. I’ll have to look at the packing slip to see if it was real stress proof or just “1144.” I know the hardness was 24/25 HRC.

I received the ISCAR SumoCham carbide insert drill (with 1,000 psi thru tool oil) and made 450 holes until we ran out of material for the job, and that included 2 bar changes. (300SFM, F.008 btw)

I guess the cutoff tool chipped earlier than what we’re used to on jobs like this so I’m guessing the material was just more abrasive or included....well....INCLUSIONS....of some undesirable form that was just making it hard in the tooling.

Maybe in the interest of experimentation I’ll try the HSS drill again in the next batch to see if it holds up any better but probably not, since I already paid for the Iscar tool.

Thank you, again, for your help!

18. Originally Posted by Matt_Maguire

Your chips look like your cutting with oil, 1144 chips for no reason.

Good luck
Matt
Neat charts, Matt! Thanks for sharing! It looks like they are all pretty similar in their recommendations. I am indeed cutting with oil, but what do you mean "1144 chips for no reason"??

19. Originally Posted by Ox
I didn't catch what size bar you are running?
I have 5000# of well seasoned and certed 9/16 hex that I would like to move some day....
(Not sure without looking if it's Fatigue or Stress)

------------------------

Think Snow Eh!
Ox
Hi Ox,

It looks like I was just asking too much from my HSS drill on this batch of material, since I did a couple bar changes with a new drill and had no problems (plus it is the same bar change program I've used for years!)

It's 3/4" round. Good luck finding someone desperately in need of 5,000 lbs of hex parts soon!

20. Originally Posted by yardbird
Maybe not?

I haven't read this whole thread. I realize you want the most holes as possible but I've been thinking 200 .406" holes 1/2" deep out of a HSS drill is that so awful?

Brent
Hi Brent! Maybe 200 holes isn't too bad but the reason I thought it may be is because I recently ran the same material (not from the same batch, but the same "spec") and made 1,000 .323" holes about .5" deep with HSS so I was surprised when I was only getting 150-200 .406" holes about .6" deep this time.

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