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Lathe, how much material can these inserts take off at a time?

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awaqa909

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#1
I get to be a parts puller for the cnc lathe every once in a while, the problem is, just about every time I'm over there, inserts are wearing down fast. One job I think I changed about 10 threading inserts, with 3 points on them. They only lasted about 3~ parts per point and I tried to get the max out of them. On a more recent job I was told that there used to be a guy who could run both sides of this particular part in a day. It's been 2 days and the 1st side still isn't done. This job has a lot of material to bulk off. (Far more then 1 part)

What I know about the inserts, one is a 35 deg finishing insert and the other is a 50deg? roughing insert. (I know it's not the 55) The finishing insert can only take off a few thousandths and once there is even a tiny nick in the insert, the finish goes bad. The roughing, sometimes it's worn to hell but still makes a part like its fine, other times a decent sized nick will need to flip/change the insert.

These are as close to that actual inserts we use. I'm not sure if they're the right size, but the look very similar, same brand in fact... not sure if they're good or not.
35 deg I don't know how to "decypher" tool numbers to get a angle or anything.
https://www.alibaba.com/product-det...l?spm=a2700.7724857.main07.335.6dab7e0faXbWHd
45-50deg which may be the exact insert, or a 906, as it says 907 on it.
https://www.alibaba.com/product-det...?spm=a2700.7724838.2017115.112.52920af5lt4sJM

The 45 has a .5"~ edge on it? But from what I understand we only take off .045" per pass. The 35 is longer, but it looks like there is a area for cutting that is only .300"~ long, but we only take a few grand off with that tool. I wonder if these inserts are being used to their full potential and causing premature wear. I know the bite size was increased at some point and the spindle load was lower, but not sure about the Z load. But I also don't know if it was slowed in any way. Speaking of speed, the lathe plaque says it can go 4k rpm, but only recently have I seen it top out at 1600rpm.

I once watched a video on how train axles were made. They had that lathe insert in what looked like full depth.

Thanks,
Awaqa909
 

Chipper5783

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#2
That REALLY depends on the component and the set up. The actual insert can handle one heck of a cut. Most machines, especially CNCs have lots of power. However, in order to take advantage of all that power you need a VERY strong set up (which includes the piece you are machining). I find most jobs, it is the set up or configuration of the part that is the limiting factor - the machine and the tooling can handle lots more load.

A train axle is a very robust component and it is pretty easy to hang onto - of course you can take a big cut.

You have not provided enough information to get a reasonable answer.
 

awaqa909

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That REALLY depends on the component and the set up. The actual insert can handle one heck of a cut. Most machines, especially CNCs have lots of power. However, in order to take advantage of all that power you need a VERY strong set up (which includes the piece you are machining). I find most jobs, it is the set up or configuration of the part that is the limiting factor - the machine and the tooling can handle lots more load.

A train axle is a very robust component and it is pretty easy to hang onto - of course you can take a big cut.

You have not provided enough information to get a reasonable answer.
I'm not sure what kind of info to provide. It's a 3 jaw chuck, that holds onto roughly 1/4" of material. The material is 6" diameter and maybe 1.25" thick. About a inch of material is to be bulked off, on the outer edge, as well as some bulk facing... Sorry about my terminology. Also trying not to tell too much about the part, don't want to get into any kind of trouble. I don't have the best memory of the part, so things are a bit vague. Believe it was mild steel. I'm not the programmer either, nor understand any of it.
 

Wreck™Wreck

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#4
What he said.

I roll the dice at first on a new part, high speed and DOC right off (this also greatly effects chip control as well) then dial it down if it eats tooling. The material plays a key role in this dance. If the chips get out of hand dial the feed rate up a bit in order to make the chip thick so it will break.

If you do not spend a large portion of your life herding chips you will never understand this.
 
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4gsr

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My questions to you are, what kind of material are you guys trying to cut on? And the hardness? What is the brand name of the machine along with the model number of the machine. With that I/we can give you an better idea of what you need to be doing. Get the insert numbers off the packages of the inserts being used, this will tell you the information needed for proper feeds and speeds and if it is the correct insert for the material being cut.
Ken
 

4ssss

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#6
Feeds and Speeds...............Feeds and Speeds..................That's what my shop teacher preached
 

Wreck™Wreck

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#7
Ask your employers if this is acceptable tool wear, if there is enough money in the part one insert edge per part may still ring with the sweet sound of profit. Whomever set it up chose the tools and cutting conditions, ask that person instead of random people on the Web.

Good Luck
 

Dan_S

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#8
My questions to you are, what kind of material are you guys trying to cut on? And the hardness?
I agree!

  1. What material is being turned?
  2. What inserts are they exactly?
  3. what's the depth of cut, sfpm, and feed being used?

If your're changing out inserts take a photo at the back of the pack and post it.


Whomever set it up chose the tools and cutting conditions, ask that person instead of random people on the Web.
You're assuming the person who set it up knows what they are doing. I have some friends in the industry who would tell you to assume everyone else is an idiot until they prove otherwise.
 

4gsr

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#10
Okay guys, lets be nice here. We are suppose to help, not criticize what the OP is asking about. He's trying to learn something positive here.
 

4gsr

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#11
I'm not sure what kind of info to provide. It's a 3 jaw chuck, that holds onto roughly 1/4" of material. The material is 6" diameter and maybe 1.25" thick. About a inch of material is to be bulked off, on the outer edge, as well as some bulk facing... Sorry about my terminology. Also trying not to tell too much about the part, don't want to get into any kind of trouble. I don't have the best memory of the part, so things are a bit vague. Believe it was mild steel. I'm not the programmer either, nor understand any of it.
They are chucking on about an 1/4" of the 6" OD disk that is 1-1/4" thick.

The jaws are probably sprung on the old 3-jaw chuck and more than likely were not bored out properly. And because of this, the part has probably poped out of the chuck a few times and causing all sorts of excitement. Because of this, they are just "babying" the making of the part. That's probably the reasoning of why they are taking such small cuts in machining of the parts. Also makes me wonder if they are cutting on some high strength material that is giving them HAVIC trying to cut it. Even though he said that it maybe mild steel.
 
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awaqa909

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I'm trying to learn this stuff, but its so vast it's like where do I start and what to learn that I can actually use. Plus when I'm at work I'm working more then learning and afterwards I'm burnt out. On the 80 CNMG, it generally wears out on the tip. I was thinking if we took a bigger bite, even if slowed down, it could make the tool last longer, but in the same time... Not quite sure how to say that. I've only ever seen the lathe throw a part on a partoff, because there's not much other option, as far as I know. Sometimes you can break it off, but sometimes even if setup to do that, it will partoff instead.

The part I originally started this topic for, is done. But still question if it could have gone faster. I'm sure they were old jaws, I'm not sure how often the lathes get new jaws. I think the lathe, a Mazak Nexus 250-II (something like that, I don't pay attention the the Mazak machine names) was set at 200psi for the jaws. Some some kind of steel, not stainless steel. I don't know anything about speeds and feeds. My lathe setupguy has been a machinist for 35 years or something (think he said he was 55) He used to give me setups all the time that I would complain about, in some way. Usually tolerances/specs.

Had to flip the toolholder pictures.
80 Deg rougher. CNMG432-TF IC907
IMG_2765.JPG
35 Deg finish. VNMG 331-NF IC907
IMG_2767.JPG
35 Deg finish. MVJNR 16-3C
IMG_2760.JPG
80 Deg rougher. MCLNR 16 4D 16M
IMG_2754.JPG
 

Dan_S

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#13
This page will be a good reference for you, as it tells you how to read the insert designations.

http://www.carbidedepot.com/formulas-insert-d.htm

CNMG432 & VNMG 331

TF and NF are the chip breakers and IC907 and IC907 are the carbide/coating grade.

The color coded letters tell you what material in general the insets are designed for.

P = steel
M = stainless steel
k = cast iron
N = non-ferrous material
S = heat resistant super alloys
H = hardened materials


underneath the 2d barcode, you can see it says "ISO M" on both packs and then feeds and speed, so these inserts are designed/rated for steel, but might be usable for other materials. The iscar product page will give you more details, more on that later.

under the "ISO M" are the general feeds and speed for steel

for the cnmg you have the following:
Vc - the surface feet per minute range - 660 to 990 surface feet per minute. This link shows you how to calculate it base on the part diameter and the rpm of the machine.
Fz - the recommended feed rate range - .0047"/rev to .0137"/rev
Ap - the recommended depth of cut, i.e. how much you are taking of the radius - .039" to .157"


if you are only taking .045" you are on the very low end of the range. if you don't know specific grade steel being turned, its better to shoot for the middle of the range and adjust from there imo.


If you know the specific material being turned you can go the iscar product page and get better recommendations for the surface footage.

CNMG 432-TF IC907
http://www.iscar.com/eCatalog/Grade.aspx?grade=IC907&item=5598518&fnum=60&mapp=IS&app=21


VNMG 331-NF IC907
http://www.iscar.com/eCatalog/Grade.aspx?grade=IC907&item=5566950&fnum=482&mapp=IS&app=24
 

4gsr

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#14
I'm trying to learn this stuff, but its so vast it's like where do I start and what to learn that I can actually use. Plus when I'm at work I'm working more then learning and afterwards I'm burnt out. On the 80 CNMG, it generally wears out on the tip. I was thinking if we took a bigger bite, even if slowed down, it could make the tool last longer, but in the same time... Not quite sure how to say that. I've only ever seen the lathe throw a part on a partoff, because there's not much other option, as far as I know. Sometimes you can break it off, but sometimes even if setup to do that, it will partoff instead.

The part I originally started this topic for, is done. But still question if it could have gone faster. I'm sure they were old jaws, I'm not sure how often the lathes get new jaws. I think the lathe, a Mazak Nexus 250-II (something like that, I don't pay attention the the Mazak machine names) was set at 200psi for the jaws. Some some kind of steel, not stainless steel. I don't know anything about speeds and feeds. My lathe setupguy has been a machinist for 35 years or something (think he said he was 55) He used to give me setups all the time that I would complain about, in some way. Usually tolerances/specs.

Had to flip the toolholder pictures.
80 Deg rougher. CNMG432-TF IC907
View attachment 246961
35 Deg finish. VNMG 331-NF IC907
View attachment 246962
35 Deg finish. MVJNR 16-3C
View attachment 246963
80 Deg rougher. MCLNR 16 4D 16M
View attachment 246964
There's a small chance I may know your setup guy. I'm only about 100 miles from you down here in Victoria.
 
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