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zuke
11-02-2002, 12:24 PM
Hi guys! I need a little help,I just started in a new shop and they're a little behind in the times.I'm trying too get'em to go to carbide inserts,but I need a little help myself.I've got an insert holder and some carbide from a previous job,but I'm not sure if they're suitable.
I'm working both H.R.S. and brass castings on the same lathe.Top speed is 745 R.P.M.
The carbides are CNMG 432-QM,and
CNMG 432-MR.Are they suitable for my applications?If not,which ones are.
Any help would be greatly appreciated!

Thrud
11-02-2002, 10:53 PM
zuke:

It depends. Their machinery may not be up to it.

To save yourself a honeywagon (manure spreader) full of hassles, I would suggest you get your boss to contact an Iscar, Kennametal, Valenite, or Sandvik Coromant dealer and have them set up a demo for them. Most dealers are happy to demo a product if the customer is willing to buy it on their approval.

You should be aware that many smaller shops run mostly HSS as it is more cost effective in their minds. It is also true that most carbide users are not using the tools to their maximum capabilities. This requires education not normally taught in a school - see if your cutting tool distributor has classes on carbide implementation. Carbide companies will come to accounts to assist them in this. All it takes is asking about it.

BrianH
11-03-2002, 08:48 PM
Good advice....I'll just talk about the inserts...

That insert would be okay on the hot-rolled, but prob. not the brass. (Are you talking about manual lathe or CNC?)

That insert is meant for taking a big chip with a lot of horsepower. My favorite insert, esp. on freer-machining stuff, is the TPG insert, usually the 332 because the bigger radius holds up better. It's a positive-rake tool, so you can get up under the chip better, as opposed to the CNMG which is a neg. rake tool with a shallow angle-of-keenness, which I think generally sucks for something like a brass casting.

Ideally, you want to look for an insert you can use on many materials, and also possibly interchange with milling cutters. The TPG is good for that; I've used that one for everything from plastic to dowel pins....

zuke
11-04-2002, 05:25 PM
Sorry I didn't get back earlier.My boss left Friday for a week of hunting,so I'm on my own till he gets back.There's a LOT of cemented carbide around the lathe,1942 stamped on it and yes it's a manual.The tool holder and carbide I got off a buddy of mine,he works in a shop that makes parts for jet engines.Yes they do a lot of hogging at first but end up with a pretty good finish in the end.The hot rolled doesn't really matter,most of it gets welded over anyhow.The brass....you know when you go into a gymnasium and see the brass fittings built into the floor?I(for now)machine those.The biggest P.I.T.A.is getting a "nice and shinny" finish on some of the wider caps,about 5.5 in dia.
What I'd like too know is what the letters after the 432 stand for,I've been given plain,tin coated(gold)and ceramic(black) coated but prefer the plain.Which letters denote finish/medium/roughing.Finishing and medium preferred.

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BrianH
11-04-2002, 06:17 PM
The "4" just means it's 1/2" across the flats and the "32" means it has a 1/32" nose radius.

And the "CNMG" means it's an 80deg. neg. rake diamond. Like I said, not a very good finisher for something soft like brass. If you have access to a tool grinder with a diamond wheel, you can put a sharper tip on an insert, then hold it sideways at an angle and put a positive-rake cutting edge on the end, then lower your tool holder to get the tip at zero (like sharpening a HSS chip-breaker).

Hope that's not TOO confusing....

zuke
11-04-2002, 06:38 PM
I've already got my tool height,and am slowly figuring out everything else.
If 32 means 1/32,what does 431 or 433 mean?and the letters that follow afterward?
I've got an Iscar manual right beside me,and it's starting to make sense.

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zuke
11-04-2002, 06:38 PM
I've already got my tool height,and am slowly figuring out everything else.
If 32 means 1/32,what does 431 or 433 mean?and the letters that follow afterward?
I've got an Iscar manual right beside me,and it's starting to make sense.

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BrianH
11-04-2002, 08:23 PM
431 is 1/62" nose radius, and 433 is 3/64" nose rad. The number doesn't nec. correspond with a fraction, it's just the methodology they came up with.

"QM" might actually be "GM" which indicates the chipbreaker...this is General-purpose mid-range. Basically a general purpose insert for a broad range of applications.

Carbide inserts are wierd...you can get designations as long as your name....

wmgeorge
11-04-2002, 08:39 PM
Brian, And the way I understand it, the bigger the radius number ie: the 433 would be a more rounded nose, smoother finish cut??

I'm using some TPG-222 on my positive rake, clamp type 1/2 inch toolholder. First time I've ever had a lathe good enough to use inserts on, and wow it worked great. I paid $45 for the Made in USA tool holder, worth every cent.
B.G.

zuke
11-04-2002, 09:37 PM
I've used inserts before,but I always let someone else have the"pleasure" of sorting which inserts to use and for what application. I just bought 5 used tool holders on e-bay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1782492764
Paid all of 16.00 for'em.Looks like 3 maybe 4 are for TNMG's the last one for SNMG's.I figure it's a cheap way to learn my way around this stuff.Looking at the last digits,it does make sense that it be rated in 1/64ths.
By the way,there's 11 letters in my last name!

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Thrud
11-05-2002, 01:10 AM
zuke:
This is how ISO classifies inserts:

xNMG - x is the letter designation of the insert shape ie: round, 55* diamond, Triangular
CxMG - x is the relief angle (N=0*)
CNxG - x is the insert tolerance
CNMx - x is the insert mounting style

-x32 - x is the edge cutting length
-4x2 - x is the insert thickness
-43x - x is the corner radius (2=1/32") metric codes are preceded by zero ie:02=o.2mm

the last three letters are optional and not controled by ISO:
-xTK - x designates right or left hand
-Rxx - xx cutting edge condition or chip control features

It is a simple system once you get used to it - looks complicated, but it is not.

Generally on an older machine you would look for positive rake inserts as they require the least horsepower. Round inserts are the toughest and have the strongest and best supported cutting edge - their large nose radius tends to chatter badly when not used aggresively (proper DOC and feed). They are used mostly on CNC machines and high horsepower manuals. Milling shells with round inserts are becoming more common because of their great strength and lower per insert cost.

zuke
11-05-2002, 03:12 PM
Thanks for the advice!The big reason for CNMG 432's is because the toolholder is free,along with a couple inserts.I also bought some toolholders on e-bay so I'll get a chance to play around a little.
My biggest concern is getting a good finish on the brass.The first pass on the brass is anywhere from .040 to .200,and being cast there are a LOT of variences till it starts coming off.
The more I look at the iscar book I've got the more sense it makes.
Like I've said,any and all advice is welcome!