CFM requirements for auto's

[chubsetc]

I have been researching lower cost auto's for a while now and don't quite understand why when you take an all pneumatic press and give it a servo indexer you actually increase the CFM requirement.  I would think that adding the electric indexer would lower it.   As an example M&R just released their info on the Diamondback S (servo indexer) and the 8/7 requires 32 CFM where as the all Pneumatic standard Diamondback 8/7 requires only 21.5 CFM.  This obviously forces you into a larger compressor on top of the cost increase for the servo.  Just wondering why this is the case.

[spotcolorsupply]

Basically the servo indexer increases the speed of the press...

The stroke, and chopper cylinders use the bulk of the CFM...

So because of the increased number of cycles per hour the press actually uses more CFM.

Keep in mind you are only cutting the air out of the index. The choppers, Lift, and Stroke are all still air... and are running faster than in an air drive machine.

[chubsetc]

So are you saying the CFM rating is based on the full-out speed of the press and at the same press speed the servo press will use less air than the all pneumatic?  So an 8/7 being operated by just 1 person is going to run basically at the same speed as the pneumatic drive because the main factor is not press capability but operator capability thus a larger compressor isn't needed?

[Evo]

So are you saying the CFM rating is based on the full-out speed of the press and at the same press speed the servo press will use less air than the all pneumatic?  So an 8/7 being operated by just 1 person is going to run basically at the same speed as the pneumatic drive because the main factor is not press capability but operator capability thus a larger compressor isn't needed?

Essentially yes, but I would give M&R a call and ask them. Press specs from most manufacturers list the maximum CFM that would be required to run the press full blast.


BTW - the Diamondback S 8/7 listed specs on the M&R site say it requires 23 CFM, not 32. So that is only 1.5 CFM more than the standard Diamondback 8/7. There is a bump up in electrical spec required but it's nothing earth shattering. (10A @ 208v)

Still, I'm betting the "S" model will print much, much faster for that small jump in required spec.

[spotcolorsupply]

So are you saying the CFM rating is based on the full-out speed of the press and at the same press speed the servo press will use less air than the all pneumatic?  So an 8/7 being operated by just 1 person is going to run basically at the same speed as the pneumatic drive because the main factor is not press capability but operator capability thus a larger compressor isn't needed?

Evo is right... The difference is almost nothing. And yes it is based on the full speed of the press running all colors.

[mk162]

This reminds me of printing for the olympics, when we had 2 autos, each printing white tees with at least 6 colors.  It was the only time that the compressor couldn't keep up.  We had to rent one for 2 weeks.  If both presses were running flat out on a 2 or 3 color design, it wasn't a problem, but once all of the heads got going, it was a problem.

I would contact M&R, my guess is they have the numbers figured for running at different speeds.

But, I wouldn't skimp on the compressor.  We overbought for 1 press, but when we had 2, it wasn't always enough, but it got us by.

[chubsetc]

Thanks for the replys, if the cfm rating is only 2 more than that shouldn't warrent a larger compressor.  By the way, I took the CFM rating off the printable pdf file which says 32 CFM, the specs directly on the webpage say 23.  If anyone from M&R sees this you might want to check that out.

[244]

Thanks for the replys, if the cfm rating is only 2 more than that shouldn't warrent a larger compressor.  By the way, I took the CFM rating off the printable pdf file which says 32 CFM, the specs directly on the webpage say 23.  If anyone from M&R sees this you might want to check that out.

The first CFM air requirements were wrong. Our engineering department has corrected it and the lower one is correct. BTW all of our requirements are for maximum cycle speeds which almost no one does but to be safe we always quote the max.

[mk162]

Rich, you should create a spreadsheet for the machines so people are aware of what to look for.  I know it's safest to go max, but it's nice to know that if you are a 1 man shop, you will probably use XX amount of air and electric.

I will say that after running several all air presses, I am looking forward to eventually moving to servo and AC heads.

[jasonl]

I own the first Diamondback S and I was adviced to get a 7.5 hp compressor to run it, so I did.  I ran large presses with ac heads for over 13 years and then bought the S.  COULDNT BE MORE HAPPY!  My numbers are as fast as ones I used to run on presses that cost 4 times as much as the S.

[chubsetc]

Jason, how many heads/platens do you have on your press? 

[jasonl]

8 color, 10 station