I am using a 5 color Heidelberg speedmaster and while printing solid jobs I have roller marks on the solid print. If my print speed is higher at 5000 sph the white streaks will show very clearly. Since by printing with a lower speed at 3500sph the white streaks/roller marks will not show clearly.

Is this problem confine to machine gears are worn off or my rollers are not to specification.

Thanks

I dont know if i can help but i will try, Are you still having this problem? And about how far are apart are the the marks starting at the the gripper end of the sheet going back to the tail of the sheet. or does it happen in the center of the sheet only.

Across the sheets can be worn rollers, bearings or transfer shock marks. Streaking from grip to tail edge, usually means worn dampeners, excess alcohol (in the fount not you!) or an inappropriate fount solution for the type of water in your area.

Are your rollers blinding or flashing - this would indicate settings and or worn rollers or calcium deposits.

Richard, what is your definition of blinding and flashing? are you talking about glazed rollers? we have tried new rollers, different fountain solution, even when we ran alcohol fountain we have had this problem unless we run 2 passes to cover this up. do you think it could be that we try to put more ink out that causes it to build up at the nip of the roller and after you get so much out it skids the roller, I mean in theory ink rollers can only carry so much ink when it passes thru the nip right? and the form rollers are not driven by gears they are driven by friction right? and it seems that these roller streaks are if measured go about the circum. of 1 form roller and you have 4 form rollers. we struggle with this problem when we do solids like 20X26 sheet full coverage. we get around this by running a solid plate and a 75 to 85% screen. what do you think?

Blinding is when the copper rollers don't accept ink in certain areas due to calcium buildup or emulsification of the ink due to overdampening.

Flashing - look at he rollers when you're actually running - does the surface seem matt or does it fluctuate, ie shiney/matt during each revolution? If so you need to reset to the copper roller.

Are the streaks from grip to tail or (as I'm betting) across the width of the sheet? Up the sheet - that's usually dampener setting, across the sheet it's roller or plate/blanket/impression cylinder setting.

Using a bump plate is a good idea for soilds on Komoris if you don't have auxiliary rollers - they're sold as a 'special ink kit' to assist in the printing on non-cmyk inks and solids, there' also oscillating forme roller to eliminate any tracking or ghosting on difficult soilds with knock-outs etc.

As for skidding rollers - hmmm, have you tried dropping the forme rollers with press at standstill and inked up - now try gripping the stock end with say a pair of slip joint pliers, can you turn it? No, I don't think so. The settings are usually quite firm enough to prevent the skidding effect. Are your forme dampeners geared or free rolling? Is there a 'streaky' look to the ink layer on the forme dampener - if so this may be being transferred to the plate - we've found that when setting dampener ink stripes if we follow the book we don't get a clean impression on solids - according to our Komori engineers, there can be some 'backing off' of the roller/dampener pressure when you are actually running, so we double the standard setting (ie if the book says 4 we use 8 etc) and at a stroke we reduced our roller marking and streaking to nil.

Hope that's not too long winded but these issue are never resolved easily - particularly long distance!

Ok Richard, were getting somewhere, I had a solid on today. went thru and checked; No end play in rollers, All ocilators and forms have the right nip, tryed the extra on the damping form roller like you said, have the packing under the plate and the blanket correct, Now we have elimated all of the roller marks except two marks in the middle of the sheet about 1/2" apart That has always been our problem now some colors dont show as bad but blue seems to be the worst. now what do you think?

Have you measured the distance from grip of sheet to first mark and then to the second mark? Do they correspond to the circumference of a particular forme roller? If they do try lifting that one roller off the forme but still in contact with the steel - this should act as a get you by auxiliary roller and ink reservoir feeding ink back to the remaining rollers without giving the roller mark. Have you tried other units? Are the marks in the same position there?

hey there richard, 3 forms are the same circum. 1 is just a little smaller. but first let tell you what happened today. we had a 3" inch solid on today gripper to tail and on the front of the plate we have the agfa test strip it was out of the image area but still able to pick up ink, this test strip was printing up in the same spot as our roller mark. now let me add more info; there is a mark at the gripper edge of the plate and the other mark is about 7" inches back from this which is the diameter of our form rollers. I starting to think were headed to the A form roller but i dont under stand what you mean when you said lift the form up and stay in contact with the steel. are you meaning a less strip on the form but keep the same strip to the oscilator? we have 4 forms and AB form have an oscilator right above them and the CD form is the same way and then there is a stationary copper roller between BC; By the way we have komoris we have 2/c and 5/c 28" press which have this same problem.

3 forme rollers - same circumference - this can't be - is this a sprint or a lithrone?

FYI 2001 press, standard diameter of forme rollers for lithrone
A = 71 B =68 C = 62 D = 75
recommended nip widths (stripe) A,B,C = 4mm D = 3
in cases of ghosting or repeats A=5 B=4.5 C=4 D=3
Damp forme roller =6

marks around the 290mm from grip edge are attributable to the paper transfer point ie where the sheet leaves the impression cylinder end transfers to the, err, transfer cylinder. best thing to do in this case is to lower the tack of the ink. In any case lowering the tack may assist in reducing roller marks.

Have you tried altering the copper oscillation point - ie oscillator mounted above D,C rollers should come to rest 100-150mm after plate gap has passed roller D.

Getting back to earlier comment re: setting each forme roller (in turn) off the plate completely whilst maintaining stripe to copper then test print 100 sheets. This would identify responsible roller if marking gets worse or better.

If all this fails you may have to resort to softer compound rollers - consult with your roller recoverer.

One or two other things you could try - back edge (non printing area before bevel) of plate may be transferring too much damp into roller pyramid. As a last resort try scotchbriteing/wirewooling this area and see if that affects the repeat - yes it'll pickup ink, and yes it will transfer to your blanket and impression but if it assists significantly you could always trim your packing.

And as a piece of lateral thought - delivery chains, are they tight or slack? Stop press with delivery gripper 10" away from release cam, grab hold of the gripper bar at one end and see what free movement you have fore and aft - is it the same both sides? is it tight or slack? There should only be slight movement - say 5 -10mm max and clearly both sides need to be the same.

Phew! Best get back to work Good luck

Have you tried printing a dry solid ? I have all solid plates made with the solid image going down to the puched edge off the plate . This stops any damping solution from transfering from the front edge off the plate to the inking forms and then repeating futher up the solid in the form off a bar.