Looking for help honing carbide inserts

Hello,
The shop that I work at has special order carbide inserts, and due to
heavy feed to speed ratios on our machines, we have found it necessary
to hone the inserts. To keep them in tolerance (.002 hone) we have put
them in a tumbler with some stones and silicon carbide sludge... this
method because its worked for us on lighter hones. This time though,
the inserts are all chipping to hell! I tried putting even one piece
at a time to fix it in case they were bumping each other, no help.
Now I am getting the blame from my boss, and whether it is somehow my
fault or not, getting the blame is just unacceptable.
Any advice from those experienced in honing carbide??
Thanks,
Erik
Reply to
Erik G
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So to make the fragile, easily broken pieces of carbide sharper, you put them in a bouncing box of rocks?
This is a troll, right?
Gunner
"Veterans, and anyone sensible, take cover when there's incoming. A cloud of testosterone makes a piss poor flack shield."
Reply to
Gunner
Actually, the stones make the carbide edges duller...the purpose is to take the sharp edges off very evenly, making the carbide more durable in heavy cutting operations...but i'm still inclined to agree with you that it's a far from brilliant process. In most instances it actually works, though.
Gunner wrote:
necessary
though,
Reply to
Erik G
I'm no rocket scientist, but I would think that if you changed the tumbling medium to either a finer grit or a softer material, it might help. You're really only polishing the edges away, right? Ron
Reply to
doo
You can't get them honed by the manufacturer? Sure, probably add to cost, but isn't what you are doing now adding the the cost as well?
michael
Reply to
michael
Seems to me you are just breaking down the edge, I bet it can be done easily by chemically attacking the binder with acid.
Reply to
bamboo
I gather you have far too many to do them by hand? Breaking the edge of carbide roughing inserts used to be the norm when I broke into the trade. The recommendation was to hone a .005" 45 degree angle on the cutting edge, which prolonged insert life considerably. For those that may not understand, negative rake inserts do not touch at the tip when in use, but cut back on the insert top, location depending on depth of cut and feed rate. It's commonly referenced as the "false cutting edge".
I'd suggest a quick stroke with a diamond hone on each face and tip------I think you could get them quite close with just a little effort.
Harold
Reply to
Harold and Susan Vordos
Or pick up one of the small bench top "lapping" machines that are collecting dust in many machine shops, holdovers from days when inserts were quite expensive.
They use a diamond wheel in the shape of a donut, held in place by magnets, so you may swap between grits quickly. They will spin at slow rpms either fixe or in a reciprocating motion, with a quickly setable table with angle gauges.
I love mine, as inserts are expensive for me. Mine is a Leonard Grind-Lap, but the name has been changed a number of times over the years, nearly all being made in Santa Ana, California.
They turn slow enough to also work marvelously well on HSS also.
Gunner
"War is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and patriotic feeling which thinks that nothing is worth war is much worse. The person who has nothing for which he is willing to fight, nothing which is more important than his own personal safety, is a miserable creature and has no chance of being free unless made and kept so by the exertions of better men than himself." - John Stewart Mill
Reply to
Gunner
Something you might try.
I examined on of the new cnc drill pointers that "honed" the drill after sharpening. Turned out they used an abrasive brush. Brush had blue plastic bristles. Located what appeard to be the same bruch in a local hardware store. Tried using it on regroud drills and HSS lathe tools. Does a wonderful job of honing, much better than I can do by hand in just a few seconds. I don't think the hardware store abrasive brush would work with carbide [I will try later today] but there should be plastic brush with SiC [diamond? borazon?] in place of AlOx abrasives. Something better than visegrips may be required to hold the inserts. Whats your volume?
GmcD
Reply to
F. George McDuffee
Silicon carbide in the brush is pretty common.
Reply to
bamboo
Thanks for all the feedback everyone.... The inserts are in large volume, a few hundred at a time. They have rake underneath them...so the hone needs to be somewhat exact... its expensive to let our vendor hone them, and they do a poor job... I think Im going to talk them into buying a silicon carbide deburring wheel bonded with nylon (3M makes one i think). Then i will see if i can dress the form of the insert on it and throw it on a surface grinder with the insert tipped about 45 degrees... its worth a shot. i may try some form of brush hone with silicon carbide also...
Reply to
Erik G
I did 10 inserts this weekend with my old lapper in about as long as it took to type this post.
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner

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