Chip Control - Episode One - The Mild Turning
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- Опубліковано 5 лют 2025
- Here's a quick chip control video for John Saunders (NYC CNC) and anyone else with a lower HP machine who is struggling to break a chip when turning gummy materials.
Material is 1018 hot rolled steel, ~2" rough OD.
Machine is a PM1660 manual engine lathe.
Tools used:
Turning Insert = Mitsubishi CNMP432 US735
Speeds & Feeds:
Rough Turning = 600 RPM (~315 SFM @ 2" OD), 0.200" DOC (on the OD), 0.008 IPR Feed
Fashions by Carhartt & Old Navy.
Hat by Otto.
Shoes by New Balance.
Body by Burrito & Tater Tot, with special considerations from BBQ Pork.
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No animals were harmed during the making of this video, but some were consumed just before, and probably right after too.
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Bumper music is "The Real Folk Blues" performed by Sapphire.
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Thanks for the video. This is the information I need to try and get a good assortment of carbide inserts as I switch to carbide with my Grizzly G4003G 12" lathe. I need to be able to cut a variety of stock without having to take out a second mortgage. So knowing what will cut the widest variety and last the longest at what speeds and feeds is invaluable but doesn't seem readily available. I look forward to any more videos you may present. Take care. Doug
Glad you found the video helpful.
Thanks for watching!
Thanks for the specifics on your insert selection. I am in the range that you are talking about, wanting the negative tools for many reasons, and also wanting the positive benefits. This should help allot. R.J.
Glad it was of some use to you.
Thanks for watching!
I would like you to explain about how to set the proper DOC and SFM based on the catalog charts. I often find myself only with the catalog and don't really have the insert's box
Which company's inserts are you using? If you can give me the brand and the insert size/shape/grade/chipbreaker, I'll see what I can come up with.
A good rule of thumb for a manual machine is to start at about half the stated SFM in the catalog for the given grade, start your radial DOC at 1X-2X the nose radius of the insert, and then push the axial feed rate until the chip starts to break reliably (bird nesting goes away). For instance, a CNMG432 insert has a 1/32" nose radius, so you'd start your radial DOC at a minimum of 1/32" to 1/16" and then keep increasing the axial feed rate from say 0.005" per rev until you get a manageable chip that breaks reliably. Once you've found your feed rate sweet spot, you can increase your radial DOC until you run into stability/rigidity issues or you run out of HP on the spindle. You may need to vary the axial feed rate up or down a bit to maintain proper chip control at the new deeper radial DOC's.
It's been my experience that the numbers on the packs are good to get you into the ballpark, but they tend to be overly optimistic on all fronts when being used on a manual machine. Most engine lathes just aren't as powerful or rigid as your average slant bed CNC lathe, so you can't rely on cutting data that's been optimized for them when running an engine lathe.
Like so many things in manual machine work, there a lot of trial and error involved in dialing in an insert for the first time.
nice video. Thanks. I only need a quality chip breaker tool for aluminum only.
is there a better, best, brand for this feature?
My go-to insert for aluminum turning comes from a company on eBay called Max-Pro tools.
They sell a purpose made insert that is fully polished and has razor sharp positive geometry cutting edges along with a pretty aggressive chipbreaker to cut down on the aluminum wool production. They make CNMG and DNMG inserts with nose radii down to just 0.005" (perfect for taking those 0.010" finish passes).
Arno also makes a very nice high positive insert for alum and brass, but they don't offer nose radii under 0.015".
Indeed. Great info man
Thank you, sir.
Great info keep em comin
Doesn't say what chip breaker it is at the end....just gives the grade
Chipbreaker is Mitsubishi "PP".
A CNMG would bog down my colchester even at 1mm DOC 0.1mm/rev feedrate...on aluminum! If I were to have only 2 tools that would be a screw clamp parting tool that can do turning and has a wiper effect, and a grooving insert boring bar. You can then just swap inserts or grind yours to do threading and everything else!
The real folk blues!
Indeed.
See you around, Space Cowboy.
I'm in Toronto, and need to order a stack of inserts. I know literally nothing about inserts other than my shop currently uses CNMG and DNMG (finishing) tips. My main foreman is thinking about switching over to WNMG as there would be six cutting tips instead of four. Do you know anything about CNMG vs WNMG for geometry as to which lasts longer and is more cost effective?
Pretty much universally, any chipbreaker and grade you can get in a CNMG style insert, you can get in a WNMG (at least from all the big name brands).
Economically, there's no down side to the WNMG because, as you said, they have six cutting tips instead of four per insert.
The included angle of the tip is 80°, which is the same as a CNMG, so for external work, there is almost nothing that a CNMG can do that a WNMG cannot. For internal work the WNMG takes up more room because it is a physically bigger insert (wider insert = larger minimum bore size for a given boring bar). This also makes the inserts more expensive (lower production volume + more tungsten used = more expensive insert), but that cost difference is more than offset by the addition of two more cutting edges.
Other than that, I see no downside.
For a wealth of info on inserts, I suggest first going to CarbideDepot(dot)(COM) and reading all their technical references (there are many), then go download and read the turning catalog from your three or five favorite vendors. Their catalogs will tell you many things that you won't find anywhere else. They should be your first line of reference when deciding what insert grade/coating you need for a given application.
I currently use CNMG inserts because that's what I've got (there's something to be said for inertia, it slows down your ability to change direction, but it makes up for that in cash outlay savings), and they're cheap and easy to find on the surplus market. I get almost everything I use off of eBay, they cost pennies on the dollar vs MSC/Travers/Etc, but you MUST know what you're looking at, or you'll get screwed or buy stuff that won't work at all for your application.
If I was buying new, exclusively from supply houses, and I didn't already have a huge stock of CNMG inserts and holders, I'd definitely be going with the WNMG.
Look at what you're using in a CNMG right now and then call and ask the MFG (or just look it up in their catalog yourself) about getting that same grade and chipbreaker in a WNMG. Chances are very good that they'll have the exact same insert available in the newer WNMG style.
Thanks for your reply. I placed an order for 10 CNMG432 10 DNMG431 10 TNMG431 and 10 WNMG (rip wallet). We don't have a holder for turning with WNMG, so I ordered one as well and the folks I dealt with were kind enough to 50% the cost. The timing was a bit pressing to order as the previous owners at the shop stopped purchasing inserts when they knew they were selling it, and the supplier guaranteed delivery by tomorrow. I've bookmarked the technical reference site you mentioned and will for sure research more as these new inserts begin to deplete. While stockpiling the inserts I need in the future I will for sure source from eBay.
I didn't understand what you meant by "there's something to be said for inertia" were you referring to changing a shop over from CNMG to WNMG or were you talking about the actual CNMG performance?
The supplier interestingly enough had the CNMGs and WNMGs priced the same so I'm curious to see how they hold up in the long run. Will ask the main foreman who does most of this kind of turning to keep track of how long they last in terms of hours of use.
I meant Institutional Inertia, or the tendency for a shop to keep doing what it has been doing because that is the path of least resistance. Every company has it to some extent, though it has been my experience that the bigger and/or older a company is, the larger the inertia it possesses (like a snowball rolling downhill).
see ya later space cowboy