What is step compared to Bar or psi?

By shanewilk5272
Published: February 15th, 2013

We have a few demags that use step instead of psi or bar. I've only been a process tech for under a year, but all of the senior techs don't seem to have a good answer as to what step really is. I know 1 bar=14.5 psi. but i have never seen anything about step. I heard something about opening valves as each step. but still not sure how you are suppose to covert it into psi. Any information on this would be great.

This system was used on

This system was used on Demags with the NCIII controller well over 20 years ago. Your conversions are wrong. Here is the right conversion: 1 step = 1.25 bar = 18 psi = 1.59% speed.

Demag made a big mistake

Demag made a big mistake going to the "Digital" molding machines. This might be why they stopped making them after only 2 years. I found a Demag manual for these press's that even has a test page for the machine. For the Injection "steps", 1 step is close to 3.11mm/sec and for the Pressure it is close to 21.03psi(178.76ppsi) per step. The problem with this is that its all theoretic and may have a variation as much as 10%. :(
I have a chart and spreadsheet to test your Demag that I gather from Demag. If you would like a copy, just text or email me

Some machines use percent (%)

Some machines use percent (%) on controller. Maybe Demags use step in lieu of %? I can't remember.
With % you have to dial in percentages and observe pressure (psi, bar,Kpa, etc) on a manometer (gauge) or trust the screen readout
If the machine is 2,200 psi max hydraulic line pressure, at 100% setting it should read VERY near that. Dial in different percentages and compare to readings

NOW decide if the machine readout is in hydraulic or plastic pressure to make things clearer. All electric pressed read in plastic pressure, but some hydraulic presses do,or can be set to do it especially German presses and other European presses.
Some presses also are or can be set volumetric for injection. This is more logical than linear.

I would like a more complete explanation of steps in Demag. I hope we are not talking of setting different fill speeds?

KOM

brent

You don't make a direct

You don't make a direct conversion, best you can do is interpolate numbers by toggling the conversion screens. Steps are not quite linear is what I've found.

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