PDA

View Full Version : Chart for what insert to use for XXXX steel?



Carld
03-02-2010, 07:03 PM
I guess everyone knows I use mostly brazed carbide. I have lately started using inserts for special metal alloys hence my question.

Where can I find a chart or list of insert makers and what their inserts are good for?

I looked at Everedes site for an insert to use in my boring bar for Hastelloy and the site suggested CT7 which is a Cermet insert. I called and a salesman said that's not what I would suggest. I said that's what your site suggests for Hastelloy and he said he suggests TLI20. After some discussion he offered to send some samples of both to try after I told him I don't want to buy 10 inserts for find out it won't do the job.

So, from past questions to other suppliers they all suggest something different. Where can I find a site or list that is honest about what insert will work for a certain metal? I am beginning to think no one really knows what to use for a certain application and everyone has their own opinion which may or may not be right.

So far it's a crap shoot to select an insert for a certain alloy.

BadDog
03-02-2010, 08:25 PM
I've been poking around on Kennametal's site for the last day or so. They have numerous charts and pages that relate various geometries and materials/coatings to various applications. Roughing, speed, interrupted, finishing, steel, stainless, cast iron, aluminum, hard, annealed, it's all in there somewhere. Don't recall the details, but it was pretty easy to drill down from the main site, once you are into the metalworking pages. Carbide Depot had a bunch of good stuff that also might be of use.

lakeside53
03-02-2010, 08:41 PM
This issue is extemely well documented on most insert manf web sites.

The two I like are Seco and Kennametal. Each has a color coded matrix system that shows what is optimal and what still works. They lead you though the selection process.

Download the Seco Turning guide - well worth reading.. the file is called MN_2008

http://www.secotools.com/wps/portal/corp/Epi_479


Here's seco's automated tools:

http://www.secotools.com/wps/portal/northamerica/Epi_494

Glenn Wegman
03-02-2010, 09:50 PM
The other issue you will run into is that the manufacturers recommenation is most likely based on a very ridgid CNC machine using relativey correct speed and feed and plenty of flood coolant, constant surface speed, and a cutting time opf 15 to 20 minutes.

Using the same insert on a manual lathe at slow speeds and dry will definitely render different results.

That may be why the tech guy recommends something different than the website or catalog.

alanganes
03-02-2010, 10:06 PM
I have bought a small amount of holders and inserts from this guy:

http://latheinserts.com/main.sc

Small family place, decent stuff, fair pricing on the stuff I got, and he is pretty free with advice. He carries some good quality stuff even for us hobbyist types. He did some mix-and-match packaging for me so I did not have to buy big batches of inserts. And he stands behind what he sells. Seems to be a nice guy, too. Might be worth a call or an email.

All disclaimers apply: no connection, just a satisfied customer, nothing in it for me, no relation, do not point towards the sun, blah, blah, blah...

Carld
03-02-2010, 11:07 PM
Thanks for the info fellows I will dig into it. One of the reasons I have not really used inserts is because they are better suited to CNC. CNC has ball screw feeds and manual has rack and pinion or lead screw and neither one can match the smooth constant feed of the ball screw. For that reason the surface finish on manual lathes always has issues whether you use HSS, brazed carbide or inserts.

My lathe is real tight but it just will not get the surface finish I want sometimes. The shear tool has given the best results so far but finishing to a shoulder is a problem I have to solve.

I have some cheap holders that use 7 deg relief triangle inserts so I am going to look for some inserts to run tests with. I also want some for my Everede boring bars.

I'm not sure inserts will even do what I want with a manual machine, I just need to find out. I do get a much better finish with the inserts at fast speed and feed as expected. I am getting a better bore finish and that's a plus and the OD is easy to hand work so if it don't help the OD it's not an issue.

The problem with manual lathes is I can't run as fast and smooth on the last pass because I have to creep up on the final dimension where as a CNC just cuts it.

I'm just looking for a better way and better finish and maybe I'm hunting the needle in the hay stack, we'll see.

lakeside53
03-03-2010, 12:06 AM
The Seco download has a great section on surface finish. And.. each of there inserts has a graphed "envelope" of speed/feed. Very interesting to see the minimum cut depth for different insert profiles.

I asked the same question of a machinist friend a few days ago - how can I sneak up on a measurement when I'm using negative rake Diamond or W finishing insert with a 0.008 minimum cut depth?. His answer was - just cut it to final from 8 thou out, or... switch to a positive rake cermet insert (fits in the negative rake holders) for the final passes. He can take a 1/2 thou in tough metals with great surface finish. Mine are on the way...

I have a very rigid 14x40 machine with CXA tooling. No issues with surface finish if my DOC/sfm/feed is within the insert spec.

BadDog
03-03-2010, 01:43 AM
Inserts were (are) a huge learning curve for me. But I've found that name brand holders and inserts are by FAR the better way to go. I buy mostly Kennametal holders, though I've got some other brands as well. I look for things like recognizable name, carbide anvils, and more than just a screw holding the insert in place. Sometimes I can find 3/4", which my blocks will hold, but far more often, at least in the inexpensive holders I'm willing to invest in, I wind up with 1" shanks and mill them down to fit. I did the same when I had an AX sized post where the biggest it would take was 1/2". Much better and actually less exepnsive than those import things that are so often found in HSM tool collections.

I also try to standardize, with a few exceptions, on just a few geometries, so that I can keep a selection of inserts for different purposes. My main work horses are CNMG43* and TNMG43*. These are some of the most common, least expensive, and offer the widest variety. I've got name brand inserts of all sorts, rarely paying more than $0.25 each. Some polished and ground with highly positive edges intended for non-ferrous finishing, all the way to fancy molded and coated inserts intended for roughing hard/tough ferrous, and so on. I've even got a few Cermets for super fine 1000 sfpm finishing in steel, and some intended for doing as Evan shows in turning a bearing race. I bought a roughly 10" tall, 12" square *stack* including a wide range of CNMG43* selections for $80 at an auction. Mostly all name brand and still in new containers. I sold less than half of them CHEAP (or traded) and cleared the cost. Must have weighed 20 lbs. I've got a partial box containing over 50 Kennametal TPG322 polished sharp inserts (forget the code, hard and brittle for light cuts in harder material, max cut around 0.030) that I bought for $20, I and I use them for day-to-day finishing in a cut down Kennametal holders with orientations suitable for L, R, and facing. I've also got a heavy roughing Kennametal holder for the CNMG43* that uses the obtuse point that is otherwise unused. Beats the heck out of those weird proprietary inserts. And I've yet to pay more than $10 for any of my name brand insert holders (well, I did pay $20 for the odd-point CNMG just becuase they are a bit unusual).

The only exceptions to these main stream inserts (which I basically have a lifetime supply of now) are my Top-Notch threading/grooving, Sandvik parting, and a moderate/small range of heavy relief boring bar inserts. If I'm short on anything related to inserts, it's in the fine finishing area, particularly non-ferrous boring bar inserts.

I still use HSS quite regularly. Mostly for finishing (particularly for boring), form tools including rounded chamfer finishing and such, and that type of thing. But my lathe does quite nicely with the selection of inserts I've acquired, and I don't have to tax my limited patience waiting a long time when I need to reduce a diameter by a few inches.

I have no idea what will work well for you and your lathe, so good luck with the experiments. The only substantial suggestion I can provide is to go for the good used holders and inserts. My examples are provided mostly to show that there is no real need to even consider lesser options. From my experience, particularly with the current economy, you'll often pay more for less when going Chinese...

oldtiffie
03-04-2010, 01:31 AM
I guess everyone knows I use mostly brazed carbide. I have lately started using inserts for special metal alloys hence my question.

Where can I find a chart or list of insert makers and what their inserts are good for?

I looked at Everedes site for an insert to use in my boring bar for Hastelloy and the site suggested CT7 which is a Cermet insert. I called and a salesman said that's not what I would suggest. I said that's what your site suggests for Hastelloy and he said he suggests TLI20. After some discussion he offered to send some samples of both to try after I told him I don't want to buy 10 inserts for find out it won't do the job.

So, from past questions to other suppliers they all suggest something different. Where can I find a site or list that is honest about what insert will work for a certain metal? I am beginning to think no one really knows what to use for a certain application and everyone has their own opinion which may or may not be right.

So far it's a crap shoot to select an insert for a certain alloy.

Carl.

Did you ever get a satisfactory answer to this question?

If not, I may be able to help but it will require me to scan and upload about 10 images to PhotoBucket.

I'd be happy to do it and to either post them here or PM the links to you.

It will take me a day or so.

Let me know.

Glenn Wegman
03-04-2010, 05:54 AM
Try this Carl...

http://www.carbidedepot.com/app-guides.htm

PixMan
03-04-2010, 07:35 AM
I really don't think there's any one chart to match grades to steels for all the different manufacturers out there. This is a VERY competitive arena, and every maker has the best....just ask 'em.

The first thing I did was nail down the tool holders. I got ANSI/ISO standard turning holders for negative rake and a few positive rake (screw-down) insert geometries that took common inserts such as CNxx43x, DNxx43x, and recently, VNxx33x. I got at least two grades for each; one C2 class for stainless steels, cast irons and non-ferrous and a C5/C6 class for steels.

Matching the grade of insert to the material is the easy part. Matching the top form geometry (a.k.a. chipbreaker) to the depth of cut and feed rate is the hard part. There's no end to the options! I have a good variety now, obtained from (mostly) Ebay auctions. When I get one that works particularly good, I buy them from MSC or a local distributor who will often be willing to beat MSC's price. Carbide Depot is another great source with great prices.

Carld
03-04-2010, 09:18 AM
It's interesting that this thread surfaced again. I was looking for it yesterday and had to resort to finding threads I started. I have downloaded and read some of the SECO manual that was recommended and found it rich with info.

I contacted Everede Tools about their inserts and they sent some samples to test with and a manual that had a chart for what insert to use with a list of metals. The Everede chart is pretty straight forward and easy to use but the insert numbers probably don't relate to other brands of inserts. For instance what is a TL120 insert made of and how does it relate to other makers inserts?

The problem I see so far with inserts selection is there is no industry standard and each company has their own ideas on compounds and what works best.

Also, the chip load, feed and speed have a great impact on surface finish as much as the quality and type of insert used. It's almost like you have no real standard if you use different brands of inserts. It seems to me you have to select one brand and use them exclusively for best results.

Also, there is the issue of CNC vs manual and that is looking to be a real issue to me. I don't see how you production CNC machinists have an easy life with all the variables. This is proving to be an interesting learning experience.

With the brazed carbide cutters I just sharpen the tool and use it and if needed put a radius and or chip breaker on it and carry on.

This insert thing is somewhat overwhelming:confused: . Oh, and I am glad it's back on page 1 as I am sure others are as confused as I am. I just didn't want to be the one to bring it back as it didn't seem to get much interest.

Now I need some Hastelloy parts to run the test on. I may have to buy some Hastelloy and that stuff is like buying gold. Also, did you know that Chile is a major producer of copper and they are shut down now and the price of copper is going up. A lot of metal prices are based on the copper price.

Paul Alciatore
03-04-2010, 09:35 AM
I'm going sideways on this, but if you are looking for a better finish on a manual lathe, you might try extending your handwheels to a larger size, a larger radius. I think a nice finish has a lot to do with constant conditions during the cut: primarily a uniform feed rate and uniform coolant feed. I have found that adding a crude wooden extension to the handles on my S'sB cross feed made it a LOT easier to get a uniform feed when cranking by hand. And I can crank continously with one hand instead of using two and swapping between them so the other hand is free to apply coolant constantly. Both of these contribute a lot to a uniform finish.

http://img.photobucket.com/albums/v55/EPAIII/P1010005-1.jpg

Here is a shot of it in action doing some milling:

http://img.photobucket.com/albums/v55/EPAIII/P1010004-1.jpg

And here is a shot showing the difference in the finish I got:

http://img.photobucket.com/albums/v55/EPAIII/P1010006-2.jpg

The one on the left is with the handle extension and on the right without.

I should make a more permanent handle, but for now this one works just fine.

As for carbide inserts, they are OK, but I prefer HSS for a nice finish because I can touch them up to a keen edge just before and even during a cut. Also, it is easier to change the geometry if things aren't working the way I want.

Carld
03-04-2010, 11:02 AM
Paul, It's true that smoothness of feed is important and hand feeding has issues. Even with auto feed on a lathe the surface finish is affected by the gears in the feed system. It depends on each gear having no friction or jump and that just won't ever happen. The only way to eliminate the gear problem is with ball screw and motor drive as on a CNC. So it's like this, Carl, just live with it and do the best you can.

I just looked in the Enco catalog and found some good cross references for different brands. It's not complete but I bet somewhere there is a list of each manufacturer and how the grades cross over. They have a good list of what each grade/type of insert will work best on.

I haven't got an MSC catalog for a long time so I ordered a 2010 catalog to see what they show.

The part that I am doing has to be done with the compound so feed is tricky where on a CNC you just set up the feed angle and SFM and do it.

What surprises me the customer said my finish was better than one of the shops with CNC got. :confused: Maybe they didn't try hard and just slapped it out.

EDIT: Glenn, the site you posted has a lot of the info I was looking for and it's a keeper.

EDIT: I was reading some things and Cermet is a coating??? From what I read carbide is carbide and the grades go from C1 to C8 with some ISO grades in there somewhere. So it's the coatings that do the whing ding things and not always the carbide. So confusing, so interesting.

BobWarfield
03-04-2010, 12:45 PM
The trouble is the manufacturers have more grades than any of the standards call for. They're trying to optimize to the nth degree as well as push their special advantages over the other manufacturers.

Most machinists I talk to lean heavily on their tooling sales people to provide recommendations and samples, keep copious notes on how things work, and once they find a combination that works they stick to it for a long time.

Not sure how much the ballscrew thing matters for the surface finish. Some probably. Exact continuously variable feedrates and exact stop every time seem like bigger factors. There are a lot of ways to rig this up on your lathe. At the very least, put a feed motor on the leadscrew instead of using the gearing that is continuously variable and providing electrical limits to stop the motor can do the trick. I've seen this done to both axes to good effect and some commercial lathes do it too.

As for there being so many variables, I think there are just as many variables in manual machining as CNC, but CNC gives you a better ability to manage them. It's easy as you are making multiple runs to vary just one or a few variables at a time until you really get things dialed in and optimized. The CNC will do exactly what you tell it over and over, but it still needs a good machinist's judgement to tell whether the end result is better or worse.

Cheers,

BW

Glenn Wegman
03-04-2010, 12:58 PM
I was reading some things and Cermet is a coating???

Nope! Cermet is Cermet. It is in the Carbide family though.

It's east to "over think" inserts. Just get a few basics for the recommended material and try them. If you don't get the finish you are looking for, run the speed up! Most inserts like surface speed due to the edge hone or prep which is not like the edge you get when sharpening your own brazed tools. The most common problem is just running them too slow and getting torn, lousy, finishes at first.

Here's some 3" 4140 Annealed I faced at 2000 rpm (because that's all I had!)

It's got some scratches and marks in it as it's ben sitting around for a month. You can just see the diffractive finish toward the top.

http://img.photobucket.com/albums/v647/Fighter1/Arbor-1.jpg

Carld
03-04-2010, 03:44 PM
Bob, how right you are on all that you said.

Glenn, the finish on the little stub shaft is what I get at 790 rpm, .004" feed and .050" DOC on a 1045 part I am making now. It's a near mirror finish and I love it. Things get bad when I go for a lighter cut at the same speed/feed but I am working on it. I'm thinking inserts for heavy cuts and then the brazed for the finish but we'll see.

I got the MSC catalog and they have a big section on inserts so with what I have I will do some reading and crossing over and see what I can do.