Buying Guide: Selecting Carbide Inserts for Metalworking

Last but not least is the whole topic of insert nomenclature. It&#;s a deep subject, one filled with exceptions and cutting tool-specific rules. Regardless, most manufacturers follow the ANSI or ISO tool identification system (and sometimes both). We won&#;t get into the details here except to say that it uses an alphanumeric code to specifies an insert&#;s shape (round, square, triangular, etc.), clearance angle (neutral to positive), tolerance (some inserts are pressed to size, while others are ground), the size of the locating hole (if any) and clamping method, its size and thickness, corner radii, and various other defining features (see the chart above for an example).

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Complex naming systems aside, however, choosing the right insert for your machining application isn&#;t as difficult as it might appear. That&#;s because cutting tool manufacturers have developed online tool advisors that walk machinists and programmers through the tool selection process. For example, Kennametal&#;s NOVO prompts users to answer questions about the metal removal process (milling, turning, or holemaking), the machine tool that will be used, workpiece material and removal amount, and expected depths of cut. It then generates a machining strategy along with insert and toolholder suggestions, ordering information, product availability, feed and speed recommendations, and more.

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Long story short, carbide insert selection is much easier than it once was, even though the number of cutting tool options has grown exponentially since the days of brazed carbide and HSS tool bits. Download a catalog, log in to NOVO, or give your local cutting tool representative a call. You&#;ll be making chips in no time.

Following that stereotypical newbie process I've bought one of the typical carbide insert tooling sets that you get from the usual chinese import sites. (And for those that always choose to chime in about HSS I have some of that also and will grind it up when I get to it).

Back to the carbide inserts though, I'm genuinely surprised at how blunt most of the inserts are. I can easily push my finger onto the cutting edge without cutting myself. Except for the threading inserts and the grooving tool which do feel a bit sharp.

My past experience tells me that blunt tools can dangerous tools so I want to make sure that this is normal before I try and turn some steel with them and potentially do some damage.

I do understand that different materials require different insert types/grades/sharpness. I have a small cnc and all the milling cutters i have for it (even the carbide ones) are extremely sharp.
From the CNC I know that Aluminum, plastic and wood need sharp cutters and from drilling I know that steel likes sharp drill bits but maybe that's a HSS drilling thing only. I've never drilled steel with a carbide.

So are these cutter inserts meant to be sharp (drill bit sharp) or is the rounded looking top of the cutting edge actually normal? Am I worrying over nothing?

I know straight up that I wouldn't go near aluminum with these. Plastic I expect will be safe to try it on because failure there won't damage anything other than the plastic. I expect that blunt inserts on steel are probably just going to chatter and/or screech loudly, like trying to drill with a blunt drill bit or a drill on reverse.

If there's anything I think that the typical youtubers who have machinist backgrounds and training leave it's it's the really simple stuff like the answers to questions like these

I've got a tuv lathe inbound (they're on backorder) and it's my first lathe. I'm a hobbyist and not a trained machinist so I've never been educated in any of this stuff. I suppose you could say I'm somewhat of a stereotypical newbie having sat through a ton of you tube videos trying to learn all I can. I do however have a lot of grey in my beard and a shed full of tools that do get used so to my credit I'm smart enough to have not killed myself doing something stupid using them. I would like to continue that patternFollowing that stereotypical newbie process I've bought one of the typical carbide insert tooling sets that you get from the usual chinese import sites.(And for those that always choose to chime in about HSS I have some of that also and will grind it up when I get to it).Back to the carbide inserts though, I'm genuinely surprised at how blunt most of the inserts are. I can easily push my finger onto the cutting edge without cutting myself. Except for the threading inserts and the grooving tool which do feel a bit sharp.My past experience tells me that blunt tools can dangerous tools so I want to make sure that this is normal before I try and turn some steel with them and potentially do some damage.I do understand that different materials require different insert types/grades/sharpness. I have a small cnc and all the milling cutters i have for it (even the carbide ones) are extremely sharp.From the CNC I know that Aluminum, plastic and wood need sharp cutters and from drilling I know that steel likes sharp drill bits but maybe that's a HSS drilling thing only. I've never drilled steel with a carbide.So are these cutter inserts meant to be sharp (drill bit sharp) or is the rounded looking top of the cutting edge actually normal? Am I worrying over nothing?I know straight up that I wouldn't go near aluminum with these. Plastic I expect will be safe to try it on because failure there won't damage anything other than the plastic. I expect that blunt inserts on steel are probably just going to chatter and/or screech loudly, like trying to drill with a blunt drill bit or a drill on reverse.If there's anything I think that the typical youtubers who have machinist backgrounds and training leave it's it's the really simple stuff like the answers to questions like these