# How many cnc machines should one really be running?



## awaqa909 (May 7, 2017)

In a workplace, with cnc machines, how many should 1 person be running at a time?  I keep forgetting to ask this, but a man came to the shop I work at and said something about how he used to run 8 mills and 2 lathes with another guy.  I thought of cnc machines right away, but not sure if he meant manual instead, which you can only really run one of those at a time right?

I've only ever ran a max of 2 at a time, witnessed a guy run 3.  I haven't run more then 1 in quite a while.  I've run machines where it seems like there isn't a care in the world about the machine crashing, then run machines with my hand constantly on the e-stop.

Whats your guys word on this?

Thanks,
    Awaqa909


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## BrianT (May 8, 2017)

From a production standpoint, I would imagine the part that is being made has much to do with that.  When I was much younger I was an operator and ran 3 cnc lathes and when the guy next to you went to the washroom you ran their 3 machines as well.


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## Tony Wells (May 8, 2017)

The answer is positively, absolutely.....it depends. Think about some of the trends in lights-out machining. A shop full of machines with _no one_ there running them. Then think about the machines that are loaded and unloaded by robots. Yes, those examples are CNC on a modern level, but before things got to that point, machining cells were and still are very popular in some places. Those cells may have 2 machines or maybe 8. Again, it depends.....this time on the part. Cycle time and part complexity and the amount of actual operator involvement determines how efficient a cell is. No reason one guy couldn't watch over half a dozen machines that are running 4 hour cycles with a 15 minute part change. Or so it is said. I have my own opinions on the subject, but that is not an uncommon perception in certain industries.

On the manual side of things, it is a bit different, even with tracer controlled machines. You might get by watching a couple of them without too many problems, but it does get risky when you add to the burden the operator already has. And that can cause mistakes, so it is not without an element of risk. But some of the same principles apply here. No sense in having a guy watch a machine for 2 shifts and do nothing else, as long as the operations are mature and the processes worked out so that little attention is required. On strictly manual machines, I have seen it done, and I have even run 4 large mills for days at a time. It usually was on one part with at least 4 operations. Two were on horizontals, and two on verticals. The timing wasn't just right, so at times one of the machines had to sit and wait, or unloading couldn't be done quickly enough.........but I promise, when I was doing it I was hopping all day and it made the day fly by. I was young so I didn't mind. 
More than one lathe would make me a little nervous. Depending (there's that word again) on what the ops were. I have run 2 on roughing identical parts, so it wasn't too confusing, but you had to have some dead time when changing parts unless you stalled beginning the cut on the second machine so that the stop points were staggered, time-wise. For me, it was more nerve wracking than running the 4 mills. Probably partly because of chip control. It's been a long time, and I try not to remember some of those old times.


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## Bob Korves (May 8, 2017)

That can be done with automatic screw machines and other production machines that have all the tools installed and the stock is automatically fed by bar feeders and the like.  But, we can't see the forest because the trees are in the way.




Let's think of hobby machinists as... artists...   Perhaps that will push us a bit farther down the road...  The acceleration is accelerating...  The reason they call it "lights out manufacturing" is because there are NO people in there.  I recently read that a Japanese television manufacturer makes 1 million televisions, up to 120 inch big screens, per month, in one factory, while using under 20 employees in the manufacturing portion of their business.  All done lights out.  Let that sink in for a while...


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## JimDawson (May 8, 2017)

I have run 2 manual lathes at the same time.  Also have run my manual lathe and CNC mill simultaneously.  I occasionally run a jobs on my router that have 8 or 9 hour cycle times, in that case I run it lights out, and it's done in the morning when I get up.  Nothing like getting paid for sleeping


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## coolidge (May 8, 2017)

Part/material dependent. If you are turning cast iron then 1 machine because your inserts can flame out without notice if you hit a chilled/hard part of the casting. If you are not standing there ready to stop the machine bad things will happen quickly. Another example would be a $100k stainless steel casting. Now if the CNC machine is spitting out small brass fittings, being fed with a bar stock feeder different story.


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## Paul in OKC (May 8, 2017)

Have run two manual lathes at the same time, both turning material with a feed stop. One time ran both lathes and two cnc machines. That was a busy night making a circle between them all. Not uncommon for people to runs a 3-4 machine cell, set up properly.


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## 4GSR (May 8, 2017)

Back when I was physically able, not too long ago, it was nothing unusual to have the saw cutting raw material, The big lathe turning OD's, The big mill face milling, and running the 16" Axelson, all at the same time.  Usually get about three to five minutes continuous running without interruption.  Time savings, a little.  With three of the machines running, especially the saw, always needed your attention. The only real problem with doing this was the main machine you were running, you had to pay attention to what you were doing.  So most of the time, it sat idle while you attended the other three.  Generally the saw was the only that would stay running while you were concentrating on the main machine, so you didn't mess up. (did I make sense on what I said?)

Most of the places I've worked at usually had two CNC lathes together or a CNC lathe and mill together for one person to run.  I have seen machining cells set up with three CNC machines.  Those cells, were run by one person and usually two of the three machines were running.  Was kind of hard for the operator to handle the third one. These were average size machines IMO.


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## Superburban (May 8, 2017)

I know a fellow that has 3 CNC machines, only him and 1 assistant. they get the machines set up, and let them run all knight. He say the most labor intense part of his operation, is packing the parts for shipment. What used to take 4 to 7 or 8 Employees per shift, and probably 5 to 10 machines, he does with 2 humans, and 3 machines. Of course, he only does large orders, less then 100 or so, is too labor intensive.


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## awaqa909 (May 8, 2017)

Superburban said:


> I know a fellow that has 3 CNC machines, only him and 1 assistant. they get the machines set up, and let them run all knight. He say the most labor intense part of his operation, is packing the parts for shipment. What used to take 4 to 7 or 8 Employees per shift, and probably 5 to 10 machines, he does with 2 humans, and 3 machines. Of course, he only does large orders, less then 100 or so, is too labor intensive.


How does one pull that off?  Do they not check parts?  What if a tool wears out?  Are these lathes with a bar feeder?


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## Superburban (May 8, 2017)

Stock bins, feeders, and I believe they are called touch probes that check the specs on the finished parts. Then conveyors that count, and drop the parts in big bins.


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## Wreck™Wreck (May 9, 2017)

awaqa909 said:


> How does one pull that off?  Do they not check parts?  What if a tool wears out?  Are these lathes with a bar feeder?


Statistical Process Control, every part can not be measured when producing 1000's of parts per hour for years.


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## Downunder Bob (May 25, 2017)

awaqa909 said:


> In a workplace, with cnc machines, how many should 1 person be running at a time?  I keep forgetting to ask this, but a man came to the shop I work at and said something about how he used to run 8 mills and 2 lathes with another guy.  I thought of cnc machines right away, but not sure if he meant manual instead, which you can only really run one of those at a time right?
> 
> I've only ever ran a max of 2 at a time, witnessed a guy run 3.  I haven't run more then 1 in quite a while.  I've run machines where it seems like there isn't a care in the world about the machine crashing, then run machines with my hand constantly on the e-stop.
> 
> ...



As others have said "it depends". 

But let me quote a mate of mine who runs his own commercial machine shop. He has a love/ hate relationship with CNC. He loves it because it pays the bills, He often runs 3 to 5 machines at a time, He employs no one, and depending on the job, will leave a machine or two running with the lights out while he goes home. He hates it because, as he says, "it aint machining, it's just programming". He would much rather get his hands on a normal lathe or milling machine and make one offs or just a few parts, in fact he will often charge only for the material used on such jobs, because he enjoys running the machine, and using his skill.


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