Sharpening carbide inserts

Just wondering how many of you all practice this & with what kind of success.

I've seen guys in the past touch up turning inserts but it seemed to me that they were lucky to make it through more than one or 2 passes before having to touch it up again.It also seemed that they were concentrating on touching up the outer edge of the insert down past the worn area.

I started playing around a few years ago touching up TPG & CNMG/SNMG inserts.After trying a few different methods I finally got it to where I could make one box of inserts last the equivalant of 3 or 4 boxes.And maybe it's just Psychosomatic but it almost seems like the inserts cut better than new after touching them up.So recently I tried my luck with milling inserts,mostly APKT,SPG & SEKR/SEAN inserts.Same thing,,they cut great & seem to last longer than the brand new edge did.They're a little harder to grind but the results are the same.

Most machinists that I know do not practice this so I'm wondering how many of you sharpen you're own carbide inserts.

I guess it depends on how your going at it, I've touched them up just to finish a job, or waiting for a new box of inserts to show up. I actually do it all the time on part off tools. For an insert that I'm really getting after it with, where I'm depending on the coating, geometry and edgeprep, I would be way too scared.

I've been running the Sandvik R390s a lot lately, and when an insert starts to go, its out of there, those cutter bodies are not cheap. Running 1400 sfm in 1018 or 1000sfm in 4140, I'm not going to take the chance, it only takes a second to lose the whole tool, I've got the collection to prove it. I save them and will back off the speed and putter through a short job with beat up inserts if I have too, touch them up if they are really bad, or use a beat up set of inserts to get a certain radius, I certainly wouldn't trust a hand sharpened insert to get after it like a factory edge, thats being penny wise and dollar foolish.

I've been doing this for quite a while. I bought one of the Accu-Finnish series II machines and it does a wonderful job on inserts. I can get a better finish with a light feed when using a sharpened insert. The downside is that I have to touch off again because after I sharpen an insert they are rarely exact. I take off as much as it requires to get a new edge. Once I have sharpened them to the point that the chipbreaking groove stops working then I toss them, however by the time I get to that stage the insert has usually done as much work as I usually get out of 3 inserts. I also use it to "adjust" the geometry of an insert if I have a special job. I have ground them to make special a thread when I have a one off jobs that doesn't justify buying a dedicated threading insert. You can usually cobble up a holder out of key stock or other handy material to get the job done.

-brian

How much can you really grind off a SEAN ? I hate to replace those in the facemills - that gets expesive fast! Wondering about how grinding will affect the chipbreaker geometry.

i touch them up to remove a built up edge. it also depends if you are paying for them out of your own pocket or not.

Damon, try Mitsubishi inserts. We've been using them for roughing lately and they hold up decently, and are very CHEAP. If I recall, last batch purchased was $2 or $3 an insert. These are SENN however, more of a utility tolerance class. I get around the looser tolerance on i.c. and etc. by measuring and grouping like-sized inserts.

There once was a Co. that specialized in regrinding inserts. They would do a slight grind, on the entire periphery, & prefered to make the corner radii larger, so they could clean up the wear. I do not know if they are still in business, I kinda doubt it. It does not seem cost effective...

If you have 250 or more of the same insert to sharpen check out randjtool.com. They offer a patented insert sharpening that allows the inserts to seat in the original pocket. No loss of tool life either.

I always resharpe what I use and get logner toollife the second time around, but i only sharpen by grinding the top leaving the geometry alone. I went so far as to grind new inserts before using them in order to not waste any time with a brand new insert.

Those round corner radii, horrible.

Its amazing how standards get lowered and then the crow accepts the lower standards (going from sharp corners to round corners, e.g.)as the norm.