Chipping WNMX insert 1044 steel

T

twr

Hot Rolled

Joined

Mar 18, 2014

Location

Kitchener Ont. Canada

• Jan 22, 2021

• #1

Hi i am turning 8" long and 5" dia bar down to 3" 1044 steel with a iscar wnmx 454 insert and its chipping the insert on entering, i broke 2 inserts so far. Running at 750/850 rpm and .016 ipr. and .120 DOC I have been plunging at .005 ipr should i not be doing a plunge at .005 and just stick with .016 ipr? Any other ideas to why it maybe chipping on entering? I have been standing over machine with may hand on the Estop.

 

Y

yardbird

Titanium

Joined

Jul 3, 2013

Location

Indiana

• Jan 22, 2021

• #2

Hey Tracy, Is that cold rolled? You're not using G96 surface feed?

I'd run it about 500 600 sfm feed at .012 see if that doesn't help?

If this is better you could up the DOC but it's not always wise to mess with shit that's working. Lol...

I don't know that particular insert. .03 rad? What do you mean plung?

Brent

 

T

twr

Hot Rolled

Joined

Mar 18, 2014

Location

Kitchener Ont. Canada

• Jan 23, 2021

• #3

Hi Brent yes its cold rolled, i am using CSS 750rpm and limited at 850rpm i dont like that bar spinning to fast. So it starts .200 in front of the part and moves in at .005 ipr then when it touches the part it ramps up to .016 ipr, its called plunge speed in my software. Insert has a .063 Radius the box says .079-.197 DOC. and 490-1150 SFM. I did try .012 and it will not break the chip i had to increase to .016.

 

A

atex57

Stainless

Joined

Sep 6, 2006

Location

SW Wisconsin

• Jan 23, 2021

• #4

Get rid of that huge nose radius. That stuff should cut like butter with the speeds and feeds you are using.

When you say "CSS 750 RPM " do you mean RPM or SFM?

On another thought, are you sure they are not counterfeit inserts?

Ed.

 

EmGo

Diamond

Joined

Apr 14, 2018

Location

in the middle of the edge of the center

• Jan 23, 2021

• #5

Are you facing or turning ? Not clear from your description. Outboard end is unsupported, I bet ? Insert chipping says to me the end of the bar is vibrating on entry. Either get a center in there to support it better or go to a more ductile insert grade. Personally, I have better luck with cnmg's than w-shape inserts. The extra corner is tempting but after you chip one or two off, it's not as good a deal. The c's seem to take a beating better, and you can get cheapies easier if you are stuck with the chipping because you can't change the process.

If there's nothing else you can do, and you have an extra tool station, toss a cnmg in there using the wide angle to get the bar past the first clunk-clunk-clunk cut. But if the work is vibrating when you start the cut, then you'll still probably chip your too-fragile inserts.

 

T

twr

Hot Rolled

Joined

Mar 18, 2014

Location

Kitchener Ont. Canada

• Jan 23, 2021

• #6

Counterfeit inserts, i hope not i bought them from a surplus machine dealer in the USA that does large volume. Its 750 rpm but limited to 850 rpm so CSS should be 1050 to 1150. I am wondering if its chipping because is coming into the cut to slow if that makes since at only 005ipr till it touches the part?

 

T

twr

Hot Rolled

Joined

Mar 18, 2014

Location

Kitchener Ont. Canada

• Jan 23, 2021

• #7

EmanuelGoldstein said:

Are you facing or turning ? Not clear from your description. Outboard end is unsupported, I bet ? Insert chipping says to me the end of the bar is vibrating on entry. Either get a center in there to support it better or go to a more ductile insert grade. Personally, I have better luck with cnmg's than w-shape inserts. The extra corner is tempting but after you chip one or two off, it's not as good a deal. The c's seem to take a beating better, and you can get cheapies easier if you are stuck with the chipping because you can't change the process.

Click to expand...

Hi i am facing first then turning and its when turning the insert chips. No i am not using a tailstock. I have to drill the bar to and my tailstock is moved manual so i am not using it. I am thinking you are right and i should be using the tailstock but its a PITA and i only have 2 more parts to finish.

 

EmGo

Diamond

Joined

Apr 14, 2018

Location

in the middle of the edge of the center

• Jan 23, 2021

• #8

twr said:

No i am not using a tailstock.

Click to expand...

Unless you have a 15" hydraulic chuck with honkin' big jaws, dollars to donuts the part is vibrating. Try it with the tailstock once, betcha the problem goes away.

 

T

twr

Hot Rolled

Joined

Mar 18, 2014

Location

Kitchener Ont. Canada

• Jan 23, 2021

• #9

Hi its a 10" chuck with gripper jaws, i think your right! I hate my tailstock i wish it had a servo to move it!

 

EmGo

Diamond

Joined

Apr 14, 2018

Location

in the middle of the edge of the center

• Jan 23, 2021

• #10

twr said:

I hate my tailstock i wish it had a servo to move it!

Click to expand...

Some of them have a pin on the carriage that you drop intp the tailstock to drag it along with. If yours doesn't, you can make something like that.

Still no fun, but a little better than dragging it along by hand.

The best one I can think of had an airlift system - punped air under the tailstock, so it slid along real easy. You could do that, too. Might be easier.

Last one I had wasn't too much fun to move, either

 

T

twr

Hot Rolled

Joined

Mar 18, 2014

Location

Kitchener Ont. Canada

• Jan 23, 2021

• #11

Hi its on a rack so you turn a big nut to move it along, It does have a hydraulic quill but its just a crap old setup and a PITA!

 

T

twr

Hot Rolled

Joined

Mar 18, 2014

Location

Kitchener Ont. Canada

• Jan 23, 2021

• #12

Hi I got them done without chipping anymore inserts. I backed the speed down and DOC next time I will be using the tailstock!