SM74 Printing Pressure Too High

Dear All,

Strange errror! Half way through a press-run, the machine cuts out the feeder and the machine stops. All the 6 units have the yellow error indicating that the printing pressure across all the units is too high.

Any ideas would be greatly appreciated.

Thanks in advance,

Hiten Bhatt.

 

well . check your packing first , then check the amoint of pressure , and if all is by the book , then you may have a problem , but i guesse you will solve it it with one of the 2 above

 

I would begin by checking that the pots on each unit are in sync with the actual printing pressure.

 

Thanks for the replies.

I have checked the printing pressure and the packing, they are both ok.

Just to confirm, how would I check the exact pressure at the machine, physically?

Hiten.

 

feeler gauges in between impression cylinder and blanket cylinder with new blanket installed and packed to press manufactures spec. unit must be on impression.

 

Thanks for that, I shall try and do that and see what we get back.

Hiten

 

i would check at a few different spots on each unit. Is your press cp2000 equipped?

 

There are some digital gauges that can give you precise measurements of the pressure.

 

Probably SSK 1 or SSK 2 boards are defective since you are claiming there is a yellow error across all units. It is the main reason to stop Feeder in CP2000 machines. You need to check the functioning of these two boards. I advise to call an engineer for checking.

Goodluck

 

if you want to check back cylinder pressure its very simple. No digital gauges are needed, you dont need packing on the blankets, this is being made way more complex than it needs to be. All you need is a long feeler gauge around 12 inches long. Thickness needs to be .35mm (.014" inch). Manually select unit to impression on. Inch machine so that blanket gap and impression gap are far away from each other. Feeler gauge should slip with heavy drag between blanket cylinder bearer and impression cylinder bearer. If you dont have a heavy drag you will need to make corrections to the servo and pot to correct this. This correction is different for each machine. I would need to know what machine you have to tell you how to correct this.

 

Thanks for all the helpful replies so far.

As an update, I had a heidelberg engineer look at the press and he says that a faulty potentiometer on the coating unit was giving the press false readings.

I shall wait for him to come back and see if the potentiometer is repairable or not.

I would still like to check all the pressures as described above, the machine is SM74-6P3+L circa 2003

Hiten

 

Potentiometers are not repairable. Just have him replace it. They are not too expensive.

 

Quick update on this one...

The potentiometer was left disconnected on the coating unit.

Problem still occurring, therefore - the engineer has pin pointed it to errors with the SSK1/SSK2 cards as suggested above.

I had the cards tested, all components ok and nothing apparently wrong with the cards.

Cards back in the press, machine is behaving so far, adjusted a pressure imbalance on unit 3 - OS/DS was not the same, that is sorted.

Lets wait and see....

 

I would recommend to have the 5 volts connector at the SSR backplane checked, the connector might be loose and even if the voltage drops to 4.5 V as a result of loose connection the SSK's would randomly generate the printing pressure high error. We once faced a similar problem where the machine would stop randomly during normal production showing the printing pressure too high fault for all units, we later had to replace the connector to resolve the fault. Hope this helps.

 

Priniting Pressure

We tried all of the suggestions and everything seems ok but the error is still there. We switched the SSK boards and the 5V is connected properly. The technician and myself are baffled, are there anymore suggestions?