What's the benefit of Ceramic inserts?

Ken from ontario

H-M Supporter - Silver Member
H-M Supporter - Silver Member
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I was recommended to buy an SCLCR tool holder until I get more comfortable grinding HSS , I followed the advice and got one with a couple of carbide inserts (plus a couple of HSS inserts) anyhow the carbide inserts broke when the workpiece(store bought M8 bolts) got a little too loose in the chuck.

Now I'm looking on ebay to buy a package of these CCMT 21-51 inserts, there are so many choices that's mind boggling, then I see some carbide inserts are advertized as "Ceramic", what's the advantage of getting ceramic? sounds gimmicky to me unless there's something that makes them better that I am not aware of.
What do you think of these Ceramic inserts?
 
Ceramic, and all the myriad combinations are generally used for either hard-turning, or extremely abrasive materials. Remember, materials get hot at high stress like the shearing action at high speed, so while it does get hot, it also gets soft. Ceramic has a much higher hot hardness than even carbide. It's granular structure lends itself to heat resistance as well as abrasion resistance.

For normal turning of average metals, it actually doesn't perform as well as carbide, IMO. Even for hard turning, I go to CBN inserts before ceramics. But they do have their uses.
 
I have limited experience with Cermet inserts but I do have some TPG made in Japan that are 320.5. They are wickedly sharp and do as fine a job of taking light cuts as anything I have used. They are uncoated and hold up well as long as I stay away from interrupted cuts and scale. Only reason I ended up with them was they were cheap at the time on ebay.
 
I was given some cermet inserts many years ago by a tool salesman, and experimented with them; I was impressed with the amount of abuse they were able to tolerate, but not enough to buy any ---
 
Ceramics are not for your general lathe work materials. They are used for as stated your hardened materials and are super brittle that don t take abuse like interupted cuts. I would think your modern cnc s may take advantage of the super high cutting speeds for certain aplications. For a home shop maybe facing a flywheel Is one application a ceramic may be used.
 
Ceramics are not for your general lathe work materials. They are used for as stated your hardened materials and are super brittle that don t take abuse like interupted cuts. I would think your modern cnc s may take advantage of the super high cutting speeds for certain aplications. For a home shop maybe facing a flywheel Is one application a ceramic may be used.
If a flywheel had any heat checks (cracks in the face, ceramic would not be advised; I would use a Kennametal K-6 or its equivalent, or a ceremet insert might be also used, they are a lot tougher than straight ceramic.
 
If a flywheel had any cracks or heat checks it would be junked as too much material,would need to be removed if at all possible to clear the issue. Ceramics aren t tough there brittle as ever. Cermet and ceramics are different animals for different applications. I ve used ceramics on flywheels on more than one occasion. That s what our machine shop at the time used but not to say there may be something better but there is always someone with something bigger better and faster. It did the job.
 
Just did a quick search as there is so much out there when it comes to tooling. Ceramic kennametal kyon for flywheels. Had no idea what is was at the time or,even if thats what is was. I am sure theres more than one way to skin a cat.
 
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