What's new
What's new

Sliding Headstock vs Fixed head lathe - low volume / high mix 0.5"-2" diameter Alum

jpgirton

Plastic
Joined
Sep 18, 2020
Sliding Headstock vs Fixed head lathe - low volume / high mix 0.5"-2" diameter Alum

Seeking feedback / recommendation on moving from fixed headstock lathes with live tooling over to sliding head-stock machines. We make tons of family type parts in aluminum with internal/external threads, broaching keyways, flats, off center cross holes, and various other special features that Mazak, Nakamuras, and Mori's can handle. However would like other opinion on the pros and cons to moving that work to a sliding head machine. Volumes vary from 20pcs to 5,000 pc runs.
 
The sliding headstock machine is for parts that have a large length to diameter ratio. If your parts fit that description, you can probably make better parts faster on a Swiss.

If they are short, or larger than 32mm OD (well, there are 38mm Swiss machines out there) then you start looking at multiple spindles and turrets on a chucker. Some parts will also be better gantry-loaded than bar fed.

So without knowing what you're making, we can't really say.

LOL okay I swear you didn't have the diameter in the title at first.
 
Assuming that you'd be using the sliding headstock machine in chucker mode...

On conventional lathes, the tools are usually easier to access. On the sliding headstock machines, the tooling area can be a bit cramped- it varies by machine, though. Changing tools can be difficult and require some contortions. This matters if you're doing lots of setups where you're changing out tools often. That cramped machining area lends itself to quicker cycle times, though. The tools are all very close together giving you low chip to chip times.

Conventional lathe turrets offer more versatility than the sliding headstock, gang-tooled machines. You can fill up a conventional turret with any variety of turning tools, live tools, boring bar holders, etc. If you need 12 OD turning tools for one job and 12 ID tool holders for the next, then you can do that. With the sliding headstock machines, you are limited to what they give you. They usually give you a lot, but it has to be enough for what you need. There is some versatility, but it's not like that of the turret machines. There are some Swiss machines with turrets, so that's an option. So, I guess just make sure that whatever machines you are considering have enough of all the different tool positions you would need for your work.

And conventional lathes are usually beefier with more powerful spindles for taking heavier cuts and pushing bigger drills. You might have to change your machining strategy when changing to sliding headstock. You mentioned broaching keyways. I'd be a little concerned about having the strength to do that on a Swiss machine. You'd have to make sure the collet closer would be up to the task as well.

I don't think you'll find any sliding headstock machines that will handle your 2" diameter parts. 38 mm is the biggest I've seen.

Overall, the sliding headstock machines would be quicker and take up floor space for a lot of complex parts, but like mentioned above, it really depends on your parts.
 
Also sliding headstock machines exponentially climb in price as they grow in size. I could imagine a new 38MM machine with all the bells and whistles on a guess would be $400k or so.
 
I think they’re roughly comparable in cost. We got a 38mm sliding headstock with independent sub spindle, XYZ on both spindles, 12’ FMB magazine bar feed, and high pressure coolant system for like $275k. That might be comparable to a twin spindle, twin turret fixed headstock I would think?

In my experience the length to diameter ratio rule for Swiss work doesn’t hold much water. I’d say rather look at parts where the work can be evenly split up between the two spindles and then bobs your uncle. I got a “short” part now that, for me, is perfect...it’s 1/2” long and 1-1/8” diameter. Turn the OD, cross drill and tap three holes on the OD in the main meanwhile the sub is drilling, counterboring, and tapping a thru-hole on center.

It might be difficult to visualize the workflow if you’re not used to it but the sales rep or people here could help you if you want to share a representative sketch of a couple of those part families. We could tell you in a heartbeat if it looks like a good Swiss part.

Like wmpy said, though, I think 38 (maybe 42?) is the biggest I’ve ever heard of.

Good luck!
 
Thanks for the feedback - I had not considered accessing the tools. We have a program that is hot right now that they are looking at different machines for - but we also need to think of long term how flexible this machine might be for other programs.
 
Also sliding headstock machines exponentially climb in price as they grow in size. I could imagine a new 38MM machine with all the bells and whistles on a guess would be $400k or so.

That's a new 20mm machine with all the bells and whistles.
 
Also sliding headstock machines exponentially climb in price as they grow in size. I could imagine a new 38MM machine with all the bells and whistles on a guess would be $400k or so.

That's a new 20mm machine with all the bells and whistles.

When I left working the man 25 years ago we got some Star SR20R's for $165k, that $400k was just a guess. Looks like the price of them has increased far and above the rate of inflation. I would imagine a fully loaded 20mm has more bells and whistles now than one from the mid 90's did. I just got true data unlimited internet 6 months ago after 10 years of not watching any video or doing much downloading of technical materials. I don't go to trade shows, so other than coming here I have been living under a rock for a couple decades machine shop tech wise. I am not a 21st century machinist, but my equipment and methods are good enough to keep my customers happy and I even actually do a little medical work.
 
Take a look at the Doosan TT1300SSYY machine. Twin spindle, twin turret with Y axis on both upper and lower. Pinch turning, pinch milling, drilling in X from both sides. Quicker cycle times.
 
Yikes. Makes me wonder what hourly rate one charges for a machine like that?

As much as you can get away with. I can get $125 an hour on just a stripped 2 axis 20 year old 16mm Swiss to medical customers, I would think that could pull in the neighborhood of $250.
 
As much as you can get away with. I can get $125 an hour on just a stripped 2 axis 20 year old 16mm Swiss to medical customers, I would think that could pull in the neighborhood of $250.

That's impressive that you can get that. I was guessing around $200/hr for the new machine.
 
As much as you can get away with. I can get $125 an hour on just a stripped 2 axis 20 year old 16mm Swiss to medical customers, I would think that could pull in the neighborhood of $250.

That's impressive that you can get that. I was guessing around $200/hr for the new machine.

That is the average, it will be a little higher once I get my material sourcing down. I have found poor suppliers have infested markets they used to not. I have gotten 303 tubing that ran worse than 304 normally does. Small diameter parts are a lot more fussy when it comes to material and tooling. For the record some parts do require simple second ops that would have been taken care of with a subspindle attachment and cross milling attachment. Nothing exotic you could not do on a manual mill or lathe. I got lucky because the customer gave me no quotes they were getting from larger Swiss shops due to low volume. Of course those shops need longer running jobs due to their ratio of programmers and set up men to machines. I have a programmer and set man for two machines. Sometimes I have ran 3 different parts on one machine in a day, fortunately a lot of their parts are similar. Great group of engineers to work with, an oddity sometimes in the medical field. I was a blind squirrel finding a nut.
 
When I left working the man 25 years ago we got some Star SR20R's for $165k, that $400k was just a guess. Looks like the price of them has increased far and above the rate of inflation. I would imagine a fully loaded 20mm has more bells and whistles now than one from the mid 90's did. I just got true data unlimited internet 6 months ago after 10 years of not watching any video or doing much downloading of technical materials. I don't go to trade shows, so other than coming here I have been living under a rock for a couple decades machine shop tech wise. I am not a 21st century machinist, but my equipment and methods are good enough to keep my customers happy and I even actually do a little medical work.

You can get a 20mm machine for half that. I was just being funny because I recently had some quoted. You did say ALL the bells and whistles. I was including a programmable B axis and 12 pot ATC for the B Axis (Yeah, it exists, and yeah, it's crazy cool), or a Laser cutting head, 10 line programmable high pressure system with 2K PSI max, mist collector, firetrace fire suppression system, 12foot barfeeder, install, and 1 year warranty.

You can definitely get a decent 20mm machine for $250K or so with just what you need to run.


Edit: Forgot to include the vid of the B axis with ATC: Citizen-Cincom L20-XII with Automatic Tool Changer - IMTS 2018 - YouTube
 
You can get a 20mm machine for half that. I was just being funny because I recently had some quoted. You did say ALL the bells and whistles. I was including a programmable B axis and 12 pot ATC for the B Axis (Yeah, it exists, and yeah, it's crazy cool), or a Laser cutting head, 10 line programmable high pressure system with 2K PSI max, mist collector, firetrace fire suppression system, 12foot barfeeder, install, and 1 year warranty.

You can definitely get a decent 20mm machine for $250K or so with just what you need to run.


Edit: Forgot to include the vid of the B axis with ATC: Citizen-Cincom L20-XII with Automatic Tool Changer - IMTS 2018 - YouTube

I should rephrase that with "All the bells and whistles I currently know about." You got me, but I admitted to living under a rock for a long time. I could not even watch You Tube in 2018. I watched that video you posted, that machine is awesome! Just wondering how many heads does that thing have programming wise, when my technological advancement stopped two programs running simultaneously in a Swiss machine was the max.
Also wonder what the tech bill would be for a bad crash on the all the bells and whistles 20mm of today?, It was $5k if the techs were local back in the day, and I usually bailed the owner out and helped with re-alignments, that was 25 years ago.
 
I think you would receive VERY valuable feedback here if you could post some representative sketches of parts you’re talking about. There’s a couple Tsugami guys here, Teachme is a Citizen wiz, etc.

I’ve been able to set up my common tools well enough that changeovers aren’t the end of the world but that’s just for me in my world. In my experience Swiss is more challenging than fixed headstock but great Odin’s beard are they fast once dialed in.
 
Yikes. Makes me wonder what hourly rate one charges for a machine like that?

It's too simplistic to look at it that way.

An hour is too short of a time period to evaluate the cost efficiency of something like a well-optioned Swiss lathe. A week is more like it.

How many parts can a machine like that churn out in 168 hours? How much labor (the dominant cost in most businesses) is required to keep it going for the entire week?
 
It's too simplistic to look at it that way.

An hour is too short of a time period to evaluate the cost efficiency of something like a well-optioned Swiss lathe. A week is more like it.

How many parts can a machine like that churn out in 168 hours? How much labor (the dominant cost in most businesses) is required to keep it going for the entire week?

Thanks. I guess I hadn't thought about it like that. It makes sense that a Swiss machine that can run nearly unattended 24/7 is worth more than a typical chucker lathe that requires an operator to make parts. Unattended operating is something I'd like to work towards, but it sure is daunting.
 








 
Back
Top