im currently hard turning an OD of 3.5965. my part is currently .008 oversized. I normally don't have issues with this but this part has a groove that goes along the length of the part. currently it is hitting this groove and breaking the tips of my inserts. Would making lighter cuts helps this? I'm currently using a66n ceramic inserts. I could switch to a kbn insert if that would help.
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Largest Manufacturing Technology Community on the Web
Stay Connected:
hard turning insert help???
- Thread starter fettersp
- Start date
- Replies 24
- Views 3,101
Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
There are some CBN tips that are supposed to be good with interrupted cuts. I'd do some searching for that, and get a manufacturers recommendation for S/F for good life.
ChipSplitter
Titanium
- Joined
- May 23, 2019
- Location
- Maybe
What material?
How hard?
Current speeds & feeds?
Good solid workholding?
Tight machine?
Are you only doing a few pieces or a long run?
Answers ^^^ will help us help you.
How hard?
Current speeds & feeds?
Good solid workholding?
Tight machine?
Are you only doing a few pieces or a long run?
Answers ^^^ will help us help you.
ChipSplitter
Titanium
- Joined
- May 23, 2019
- Location
- Maybe
You could try carbide. With some TLC and the right grade you should come out fine.
I would try Seco's TP0501 grade at 150-200 SFM.
CBN typically doesn't like interruptions, carbide would likely do better.
Breaking CBN inserts will remove your profit margin quicker than Wile-E-Coyote.
I would try Seco's TP0501 grade at 150-200 SFM.
CBN typically doesn't like interruptions, carbide would likely do better.
Breaking CBN inserts will remove your profit margin quicker than Wile-E-Coyote.
Gordon Heaton
Titanium
- Joined
- Feb 19, 2007
- Location
- St. George, Utah
Carbide might be difficult with only .008 DOC in 58-60rc
Hardplates
Stainless
- Joined
- May 8, 2019
- Location
- What once was a free country
CBN and ceramic rely on heat to help plasticize the material so with an interrupted cut you actually need to increase the SFM. The greater the interruption percentage the greater the SFM.
IMO 250 is way too slow. I prefer to run fast with fine feed. A friend of mine turns hard pump impellers and spins them super fast since there is more interruption than there is cut.
IMO 250 is way too slow. I prefer to run fast with fine feed. A friend of mine turns hard pump impellers and spins them super fast since there is more interruption than there is cut.
michiganbuck
Diamond
- Joined
- Jun 28, 2012
- Location
- Mt Clemens, Michigan 48035
you know I would use the G word...sounds like a grind it job.
CarbideBob
Diamond
- Joined
- Jan 14, 2007
- Location
- Flushing/Flint, Michigan
T-land angle.
This not much of an option buying catalog standards but a higher angle could be put on your bits by a outside shop.
Trick here is to take the impact not on the cutting edge if you are chipping out.
Total failure and break on a good edge different if you pass TRS. This is hard to know which is the first to happen without spending a lot of time.
SFM seems so way slow. First thing I would do is way crank up the RPM. (that seems all wrong to everything in the gut)
In this hardness using ceramics or CBN fire is good.
There will always be an out of round problem turning this be it sub-microns or thousandths.
Grinding is better and much lower high to low but it will still be there.
250 in ceramic is way slow. Spin that puppy.
Bob
This not much of an option buying catalog standards but a higher angle could be put on your bits by a outside shop.
Trick here is to take the impact not on the cutting edge if you are chipping out.
Total failure and break on a good edge different if you pass TRS. This is hard to know which is the first to happen without spending a lot of time.
SFM seems so way slow. First thing I would do is way crank up the RPM. (that seems all wrong to everything in the gut)
In this hardness using ceramics or CBN fire is good.
There will always be an out of round problem turning this be it sub-microns or thousandths.
Grinding is better and much lower high to low but it will still be there.
250 in ceramic is way slow. Spin that puppy.
Bob
Shop Supply Guru
Hot Rolled
- Joined
- May 3, 2016
- Location
- Ohio USA
Reach out to me tomorrow and we can talk over the application and I’ll send over trial tools. If this is the shop I’m thinking it is I’d love to help!
ChipSplitter
Titanium
- Joined
- May 23, 2019
- Location
- Maybe
We've used this exact insert in 60Rc...: EDP: 5523024 - Part Number: CCMT060202FA TT5080 - Series: CCMT FA Chipbreaker
And that was barely .008" IIRC. YMMV
Or you could do like Hardplates and CarbideBob said and just kick the SFM way up with CBN.
hvnlymachining
Hot Rolled
- Joined
- Jun 21, 2019
- Location
- St.Onge
we've had very good luck with the Kennametal Kyon Ky3000 grade inserts, keep it under .020 depth of cut if you want more than one pass per edge. I have taken .0005 cuts with good success but I hear it's not recommended for best service life.
I just faced some Rockwell C 62-ish hard bushings last week without a bit of trouble, left a beautiful finish too. the "chip" is more of a nearly liquid string glowing a bright orange or red on hard materials and it won't break a real chip. we always run dry just because we have only ran it on manual machines. just as an experiment dad faced and turned down an old pickup axle with the same inserts right on through the lug stud holes, and made a tool with the remaining stub with just one cutting edge of the insert. they're our go to on interrupted cuts in hard stuff now. Good luck!
I just faced some Rockwell C 62-ish hard bushings last week without a bit of trouble, left a beautiful finish too. the "chip" is more of a nearly liquid string glowing a bright orange or red on hard materials and it won't break a real chip. we always run dry just because we have only ran it on manual machines. just as an experiment dad faced and turned down an old pickup axle with the same inserts right on through the lug stud holes, and made a tool with the remaining stub with just one cutting edge of the insert. they're our go to on interrupted cuts in hard stuff now. Good luck!
Mud
Diamond
- Joined
- May 20, 2002
- Location
- South Central PA
FWIW I use Sumitomo BN200 CBN on interrupted cuts with great success. BN250 is a little harder, the harder grades above that chip easier. BN200 and BN250 are very forgiving for me, I can take very light cuts when needed, and they last a long time without chipping.
Dan from Oakland
Titanium
- Joined
- Sep 15, 2005
- Location
- Oakland, CA
Can you break the corner on the edges of the groove before turning? We bore 62Rc gears that have an internal keyway, and simply breaking the edge on the keyways makes the CBN tools last much longer.
gregormarwick
Diamond
- Joined
- Feb 7, 2007
- Location
- Aberdeen, UK
I have done a fair bit of hard interrupted turning with Sandvik CBN grade 7115* and had great results. I agree that surface speed is too low. I would normally start at around 120m/min, which is basically 400sfm.
I've had more failures than successes trying to hard turn with ceramics, always just go straight to CBN now.
*I think that grade is superceded now though - I think 7315 is the current equivalent.
I've had more failures than successes trying to hard turn with ceramics, always just go straight to CBN now.
*I think that grade is superceded now though - I think 7315 is the current equivalent.
ADFToolmaker
Cast Iron
- Joined
- Mar 12, 2012
- Location
- Hamilton, New Zealand
What's your secret for getting H13 up to 60hrc?
Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
Might be surface hardness after supplemental carbon or nitrogen diffusion, in some conditions Rc can be over 70:
Evaluation of carbon diffusion in heat treatment of H13 tool steel under different atmospheric conditions - ScienceDirect
EmGo
Diamond
- Joined
- Apr 14, 2018
You and me together forever, Buck.
Are you scared yet ?
I don't know why people are so afraid of grinding ....
michiganbuck
Diamond
- Joined
- Jun 28, 2012
- Location
- Mt Clemens, Michigan 48035
I have been out of selecting inserts for some time. We tried and had success with c-6 grades like carboloy 350-370 and valentine Vic 67 (if I’m remembering right) for interrupted hard steel. The carboloy we had them put a negative top edge land, guessing 7* negative and a width of about .005 with being sharp edged. This is much like a cast iron insert..It seemed the negitive edge gave better heat aborbtion and caused less friction cratering.
We had some jobs that a hone edge edge would reduce start-up chipping. A brush on a wire wheel or on a bright boy weel would break in an insert and so it would get past start-up chipping. Some times just .001 -.002 edge roll/radius.
Carboloy was right down the street and we would do testing new grades and experimental grades. I even had some of the grade mix data at one time.
But for 3 1/2 x 5" long and only 4 parts with .008-take it seems one could grind them in less time than it takes to read these PM posts.
We had some jobs that a hone edge edge would reduce start-up chipping. A brush on a wire wheel or on a bright boy weel would break in an insert and so it would get past start-up chipping. Some times just .001 -.002 edge roll/radius.
Carboloy was right down the street and we would do testing new grades and experimental grades. I even had some of the grade mix data at one time.
But for 3 1/2 x 5" long and only 4 parts with .008-take it seems one could grind them in less time than it takes to read these PM posts.
