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Milling Inserts and Boring/Turning Inserts

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Braveheart13

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#1
I noticed that we only had one insert for our boring bar at work and went on MSC to order more. When I found the page with the different categories on inserts, I noticed that there were Boring Inserts and Milling Inserts. I know that they both come in all shape and sizes, but both do come in the triangular shape that I was needing. Now I ordered the right one, but I got to wondering, what is the difference in those two type of inserts? And are they interchangeable?
 

Cadillac

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#2
Numbers,letters,pics?
 

BaronJ

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#3
Generally speaking, both yes and no ! Insert technology has come on in leaps and bounds in recent years. What has happened is that inserts have become more and more specialised. A different insert for each material type, different nose radius for different cuts and speeds. Almost to the point of a particular insert for every type of job.

So whilst from a hobbyist point of view they may be interchangeable, not from a commercial one !
 

benmychree

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#4
Generally, I'd think that a milling insert would be more impact resistant than a turning/boring insert.
 

mmcmdl

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#5
I have my Valenite handy reference in front of me now . I've had this for 30 years minimum . At that time they had more than 2200 insert sizes and over 6400 insert selections . Multiply that by how many companies are now selling cutters ! Buy the size insert your tooling calls for and the grade suited for the material . Edit ........since 1983. Tool seats and clamps very , chip breakers , clearance , tnr , different grades etc etc etc .
 

benmychree

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#6
Back in the day, it was easier; only perhaps 1/2 dozen manufacturers and a dozen grades for each one.
 

Bob Korves

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#7
Internal tools like boring bars need more clearance below the cutting edge than external tools do.
 

benmychree

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#8
Back in the day, it was easier, Kennametal, Vascoloy/ Ramet, Valenite, Krupp Widia. and several others, with a dozen grades, or so -----
Krupp was the inventor of carbides, one of those accidental earth shaking discoveries; they "invented" it as a material for wire drawing dies, and a worker took a broken die and sharpened it into a cutting tool and tried it out, the rest is, as they say, history.
 

benmychree

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Krupp called it "Widia metal"; translation,
"like Diamond".
 

benmychree

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#10
Internal tools like boring bars need more clearance below the cutting edge than external tools do.
But then, TP inserts have the same clearance for turning and boring ---
 

Bob Korves

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#11
But then, TP inserts have the same clearance for turning and boring ---
Yes, and many holders do not hold the insert 90 degrees to the work, either. Negative insert mounting is common, and makes for a stronger setup, where the insert itself has zero degrees clearance, which makes it stronger. A lot of the setups we use were probably invented by we machinists for expedience, not by the manufacturers.

And I do agree, John, that there are now so many styles and sizes of inserts and holders that you can have a pile of random inserts and holders with none of them compatible to get a job done. I am constantly thankful that I have a bunch of HSS laying around to make what I need.
 

benmychree

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#12
The shop where I apprenticed had no positive rake tooling at all when I worked there, only after I left in 1970 did they buy some positive rake face mills called "whisper cut"; the negative rake mills did make a lot of noise! They were against the idea of positive rake tools because the inserts had half the number of cutting edges --- saying nothing of the higher productivity of positive rake tools due to lower power consumption and the ability to take deeper cuts and the ability to attain better finishes. I constantly comment on people's gravitating to negative rake tools on this forum, where most use small low powered machines for whatever reason, including the old one about more cutting edges. The fact is that positive rake tools are much easier on the machines, and allow deeper cuts, and result in better surface finishes and usually better chip control.
And, also yes, HSS tooling is much more appropriate for the low powered machines, members seem to be resistant to learning how to grind them and go the easy (and expensive way) and use inserts, and talk of depth of cut expressed in small numbers of thousandths.
On my 9" Monarch lathe, I was using turning tools ground with simple straight relief angles, and cutting depth in steel was limited to about 1/16"; I then remembered how I was taught in school to grind a roughing tool for (mostly) use on 10" South Bend lathes such as the class had most of, it was an angled tool with a ground in chip breaker, ground on the edge of a 12" wheel; all the students were given a piece of key stock to practice on, and when he became proficient and presented the teacher with a satisfactory grind job, he was given a new 1/4" tool bit to grind and use (and keep) for the duration of the class. I ground several of them for my Monarch, and what a difference! Deeper cuts, and much better chip control! I also shortened the drive belt, it made a large difference also ---
 
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