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Please recommend turning center

InternetBob

Plastic
Joined
Sep 12, 2020
My company is looking to upgrade equipment for a high aspect ratio part, OD machining only.

Steel bar is gundrilled, honed, then OD ground - one end finish featured then flipped and completed. We’re a bit labor light and are looking to consolidate some ops into one run.

I’ve looked at DMG NTX machines - very cool - I think too expensive for us.

Maybe smaller millturn, with programmable steady? Also looking at twin/twin and pulling workpiece with second spindle.

Hoping collective wisdom can shed some light on a good solution - appreciate any help
 
Diameter, length, and quantity of parts? Ballpark budget? A little more detail might help you get better feedback.
 
Size needed? Budget? Control preference?
I used to work for Doosan and they were a great value. A lot of machine for the money and less than than the bigger names. Great bang for the buck.
 
Diameter, length, and quantity of parts? Ballpark budget? A little more detail might help you get better feedback.

Part is 25”, most of the length is under .5” - spindle interfaces on either end. It’s made from 32-34rc 15-5. Volume has jumped to 12-15k for 2021 (why I’m here talking to you guys). I think we’re going to get beaten to a pulp trying to produce the way we are now.

To me, 300k seems high but possible. 500+ is likely too high. Does that help? Really appreciate any input
 
Size needed? Budget? Control preference?
I used to work for Doosan and they were a great value. A lot of machine for the money and less than than the bigger names. Great bang for the buck.

I will check out Doosan - we don’t have a control preference. I think we can stomach 300k, 500+ probably not. Willing to do what’s required to consolidate work.
 
At that length-to-diameter ratio, you definitely will have to use pinch turning, or steady-rest turning, on a typical CNC lathe.

Often parts that long and skinny are made on CNC swiss screw machines...

Talk to the machine tool companies, a challenging part like that needs their input on what equipment you need.

ToolCat
 
Have a few dealers test run your part and see if pinch turning may be of benefit to you.

Haven’t had any luck with that - we’ve been through two big distributors - with neither successfully able to pinch turn. I think it may be an option if a live steady was used (but that wasn’t available for testing).
 
Often parts that long and skinny are made on CNC swiss screw machines...

I have no idea what the max stroke is on a CNC Swiss these days, the longest I have heard mentioned here is 13". Whether you can re chuck and get a 25" part would depend on the outside configuration. More details would be needed. Also the depth of the gundrill hasn't been mentioned. That would need to be done on the front end.
 
Just a few idea for you to look in to.

I have no clue on straightness but a box turning tool is an optio but very finicky to get working.

Another option is something mentioned in my Mazak manual and that is Swiss style turning on a sub spindle machine.

Basically have a tight fitting collet/guide bushing type arrangement in the headstock side and grab the part with the sub spindle and use the sub to pull the part. The cutting tool basically only moves in the x axis and the sub spindle controls the z.

That can allow parts much longer than the typical Swiss can accommodate.

Call Mazak and for 300k they may have a solution to your problem. But I bet any sub spindle machine could accomplish this with proper programming. Mazak had this in a 20 y/o manual so it’s not anything new.
 
I would say Doosan but the dealer here in washington is Ellison and there service and support is just not there anymore ,,,I keep thinking Doosan well get a new dealer in this area and see that there customers are supported. The two Doosans I had DNM5700 and a 220LSYC seemed like nice machines but Ellison lost all of there good technicians when Mori left them ,,, Ellison is all ready closing some of there dealerships and my understanding is the washington dealership is down to 2 people . Hard to take care of your customers when you don`t have the staff to do it .
 
Haven’t had any luck with that - we’ve been through two big distributors - with neither successfully able to pinch turn. I think it may be an option if a live steady was used (but that wasn’t available for testing).

Maybe turn the part in sections. Pull the bar with the sub a few inches at a time.

You'll want high quality dead length collet chucks and centerless grind your bars (which I think you're already doing). Concentricity among sections can be held within a few tenths.
 
Talk to Selway in CA about doing a twin spindle lathe as a pseudo-swiss machine Selway Machine Tool Co. Their top apps guy has done it before on a Nakamura-Tome using light chuck pressure on the main collet and pulling the part out with the sub.
 
I think TK`s idea would work with pulling the part with the sub , it might be a good idea to find a local shop around you with a machine like your looking for and just be open and tell them you need to see if it well work for your parts and pay them by the hour to not only test out the idea but also to show you how to setup and run the part. Learning a new machine and new control is tricky and trying to do a tricky part at the same time would not be fun ,,, it sounds like your wanting to produce parts and not be a job shop so spending money to get you up and making parts fast is what you need ,,, I would start my asking your dealer what shop you should work with ,, most better dealers know there customers and could really help you
 
I will look into different twin spindle machines and see if I can get manufacturers to prove a pulling process.

I’m not a big brand guy - I guess I’ll try the US manus first -
 
I will look into different twin spindle machines and see if I can get manufacturers to prove a pulling process.

I’m not a big brand guy - I guess I’ll try the US manus first -

Most Mazaks are made in Kentucky. Some other "off shore" names are also made in the US.
 
I will look into different twin spindle machines and see if I can get manufacturers to prove a pulling process.

I’m not a big brand guy - I guess I’ll try the US manus first -

The process has been around for a while. The first time I heard of it was being done on an EMCO Turning: EMCO lathes and milling machines for CNC turning and milling at least 10 years ago. I think there was even an article in CNC West about the application. I know Methods has done it on a Nakamura-Tome NTJ like this one NTJ-100 | Methods Machine Tools but the guy who did the turn key is at Selway now so I'd be inclined to go looking there first. Fundamentally it's just a macro or a post edit that swaps a z-axis turret move for a sub-spindle movement so just about anyone should be able to pull it off.
 
The process has been around for a while. The first time I heard of it was being done on an EMCO Turning: EMCO lathes and milling machines for CNC turning and milling at least 10 years ago. I think there was even an article in CNC West about the application. I know Methods has done it on a Nakamura-Tome NTJ like this one NTJ-100 | Methods Machine Tools but the guy who did the turn key is at Selway now so I'd be inclined to go looking there first. Fundamentally it's just a macro or a post edit that swaps a z-axis turret move for a sub-spindle movement so just about anyone should be able to pull it off.


Like I mentioned earlier Mazak has been doing it for Atleast 20+ years as its in my manual from 1996.

Mazak fits the price range and keeps it to a domestic based machine.

When I called to get a quote they really were pushing for me to come and check out a machine and run it but i still haven’t gotten the quote and that was about a week ago.

So I’m betting they will be very happy to help you get a process but may be harder to get them to sell you the darn machine.
 
Part is 25”, most of the length is under .5” - spindle interfaces on either end. It’s made from 32-34rc 15-5. Volume has jumped to 12-15k for 2021 (why I’m here talking to you guys). I think we’re going to get beaten to a pulp trying to produce the way we are now.

To me, 300k seems high but possible. 500+ is likely too high. Does that help? Really appreciate any input

You wont even come close to touching a new NTX for your high budget. But they are beasts!
 








 
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