First pull register

[Prepper]

We have a Heidelberg 72SP and image punched film that we plate onto punched plates so our image on plates should be in good register. From there we mount the plates on the pins on the plate clamps of the press. I've had a hard time understanding why our first pull register isn't nearly dead on but the pressmen say they mount the plate, then tighten it down and make any adjustments if needed and then before they mount the next run they have to re-zero the plate clamps and that is where they have some variation is how close to perfect they can do that and then also that different operators tightening things down differenty has quite an effect on it also.

Along the same lines, what is the amount of side to side and around the cylinder adjustment they have at the console on this press? Is it possible with everything being punched and pinned that it would be possible to line it up on the fly and not have to stop and adjust the plates, or at least very much?

Just looking for whatever input anyone has on this process,
Thanks

 

[Al Ferrari]

Have you raised these questions with the press manufacturer? Or do you not have a relationship with them?

Perhaps the zero settings for at least some of the plate clamps are a bit off.

Al

 

[akiyama_king]

this machine is obviously at the very newst 1994, so over time the sepeate sections of the front edge of the clamp (the bit they Zero) are never going to get perfectly Zeroed, and also no printer can mount a plate perfectly straight anyway so even if the clamps were perfect theyll still have to twist something

Althuh on my last press you dont have to zero the clamp as you only twist the back dge of the clamp which doesnt matter if it is not centred

Circumfrentially ( around the cylinder) they have near enough no limit because they can swing the cylinders if needed (but when we have to swing a cylinder We start to huff and puff alot)

Lateraly (Across) im not too sure because i rarely have to go to the limit, but it hinkt hey have just over 2 mill

 

[Al Ferrari]

I would be inclined to agree with that, but note that KBA claims that on their Genus press, the plates go on in register every time (their claim, not mine).

Al

 

[akiyama_king]

I would be inclined to agree with that, but note that KBA claims that on their Genus press, the plates go on in register every time (their claim, not mine).

Al

Wow, KBA seem to love pressmen, i read somewere that on its new press, it actually regisers the Plates according to the Register marks before even taking a pull,
and thats on a B1 press,

no wonder were all losing are jobs

 

[rbailleu]

yeah I saw that at graph expo simuchanger and plate scanner to put in register. pretty soon we won't even need a human to operate the press. just a trained monkey like sales.

 

[RobC]

One simple thing that we did that improved the alignment of our plates was to simply put more pressure by hand to hold the plate in place. This almost eliminated any swing moves. We have our plate punch angled at about 75 degrees, - trying to use gravity to keep the plate against the edge of the punch. Then we use one hand and press the plate VERY firmly downward against the edge of the plate punch to keep it from backing away slightly when the punch handle is pulled.

 

[KRizzo]

KRizzo Director of Technical and Lean Services

KRizzo Director of Technical and Lean Services

1. Test film and plate punch squareness accuracy. Punchase should be set vertically at
about 60 decgree angle.
2. Test plate making (film or CTP) accuracy with register grids.
3. Perform maintenance to plate clamps and re-set clamp pressure.
4. Test the plate cylinders and pin system and re-set to true zero points with register grid
plates
5. When mounting plates on impression, snug up tail edge plate clamps from middle to out
side edges.
> Do not snug up lead edge clamps. If they need snugging, then the maintenance you
did was not thoruogh, do it again. or you did not properly snug up the plate in the first
place.

These test are commonly performed by Printing Industries of America.

Ken Rizzo
Director Technical and Lean Services
Center for Technology and Research
Printing Industries of America

 

[PSchw]

The front plate clamp is the most important one. If this is not zeroed to the cylinder correct you will have variations.
Ken is right the press can only repeat the accuracy of the pre-press. There are new plate clamps out which all allow the pressman to zero themselves the other style is with a pin system the plate clamp is zeroed to the plate cylinder now the holes in either the plate clamp or the cylinder will wear out and your press register will be off.
If you need more info about plate clamps contact me by email [email protected]

 

[otherthoughts]

For what it's worth

For what it's worth

The last press I ran was a Heidelberg MOFPH. Not the same as a 72SP, but it is probably a fair comparison here.

On the first pull
I expected all crop marks to be printing in contact with each other at the lead edge of the sheet. At the tail end of the sheet I expected the same 75% of the time.

In other words, all lateral and circumferential register marks should be no more than a line's width away from being in perfect register on the first pull.

If one press crew/shift achieves accurate results regularly,(Indicating that the press zero's are accurate), then every crew/shift on that press should be capable of it as well.

If the first pull regularly has one or more colors greater than a line's width out of register, regardless of the crew. Then look for a pattern,for example

"the magenta marks are usually low and to the left on the drive side of the press on the first pull".​

Of course such a pattern would indicate that the zero's on the magenta unit are not set accurately.

To test the accuracy of your plate-making reliability with "punched film", expose the same piece of punched film(like magenta for example) 4 times in a row to the very same plate. Removing and replacing the punched film each and every time between these 4 exposures. After developing the test plate, If these four exposures register dot for dot, then you are Golden. If however the four exposures are all over the place, look into why that is.

Alternatively, you could burn an entire 4 color job on one plate. The results of this test plate are ostensibly what you provide to the press-room in terms of registration.

Regards
otherthoughts

 

[KRizzo]

The same goes for CTP equipment. Expose the Printing Industries of America Register Test Grid twice through the CTP unit, but don't process the plate till after the second exposure. Then examine it with a minimum of 20X magnifier.

Ken Rizzo
Director
Center for Technology and Research

 

[PeterA]

What happens is that pressmen distorte the plate - the only option u have is to sell the press and get one with semi auto platemounting - I did that in 1992
Peter

 

[KRizzo]

First pull yield is a segment of the Lean Manufacturing tool "Quick Changeover". I have seen many presses and makereadies in many plants over the years. I have seen manually mounted plates on presses vertually achieve first pull register. It's all in the list I provided earlier.