PRESSROOM TROUBLESHOOTING CHART
Contents
1. Nick in doctor blade Press out of alignment A roller out of alignment Build up of ink tape or foreign matter on press Too much heat one web such As polyethytlene Suggested Remedy Be sure printing sections are locked firmly in place when impression is properly set Check concentricity of plate cylinder and gears plate cylinder shaft for flexing journals and bearings for excessive wear consider nature of printing plate design Check for dried ink in gear teeth Keep fountains and Reservoirs covered Add Normal propyl acetate Add rich true solvent To return ink to proper balance Filter particles out in circulation system and clean plates and anilox Check plates Add antifoam to ink Check fountain guards ink sling rings and pans for over flow leaks Sharp spot on anilox can cut fountain roll Polish anilox and grind streak out of fountain roll Hone or replace doctor blade Check press alignment Check individual rolls for alignment Clean all rolls of foreign matter Reduce web temperature 10 Table 13 1 PRESSROOM TROUBLESHOOTING CHART Continued Defects How Recognized Probable Causes Suggested Remedy 5 Web guides not operating or 5 Check and clean web set properly Guides regularly per manufacturer s instructions Set web guides and position cores so that web will unwind and rewind at an equal measu2. Excessively fine type design or anilox screen selection Souring or precipitation ion of ink vehicle solids caused by moisture absorption by the solvent in wet film Too much pressure Rubber roller too soft Excessive plate inking 3 6 Suggested Remedy Proper ink selection one having more hold out Capability Add wax to ink Set proper pressure between ink transfer roll and plate Use proper solvents and fountain covers Control pressure setting of Ink roller nip Select proper ink rollers for design and material being printed Maintain proper ink Viscosity Check often Clean or dust material when necessary And avoid having ink too tacky Use static eliminator bars Use well dispersed inks Strain ink 3 Check design for suitability for flexo work i e sufficient open areas proper type face etc 4 See section under Souring Check pressure settings Use 10 points higher durometer Select finer metering roll or improve wipe 4 PRESSROOM TROUBLESHOOTI NG CHART Continued Defects Film curl Flat process Printing Ghosting Halo How Recognized Curl over on edges cellophane Lack of contrast Hazy milky A faint image of a plate portion within a printed solid A hazy colorless image of the print on in line unprinted areas of film An unwanted line surrounding a printed image
3. film temperature 2 Introduce moisture into afterdryer chamber or tunnel 3 Direct web through remoisturing chamber Adjust plate thickness to achieve pitch line 1 Proper solvent selection 2 Properly balanced between color dryers no excessive air movement in vicinity of plates or rolls by fans or open windows doors etc 3 Use fountain covers 4 Proper selection of ink for material being printed 5 Wash plates after color approval and before full speed run 1 Use of proper solvents 2 Controlled ink viscosities Make viscosity cup every checks every 20 to 30 minutes 3 Adequate and balanced drying system to accommodate press speeds 3 PRESSROOM TROUBLESHOOTING CHART Defects How Recognized Ink penetration of paper Tacky surface of Feathering Irregular string like Fil in edges around print often on trailing edges Piling or specking of excess ink on and around printing surface of plates especially with relation to small type and screen dots Probable Cause 4 Improper ink jai Lack of slip Improper pressure between ink transfer roll and and plate Ink drying on the plate or anilox Improper setting of ink roller nip Improper ink rollers Uncontrolled ink viscosity 6 Lint being picked up from material on plate 7 Static electricity 1 Specks of ink pigment 2 3 Foreign matter in ink
4. Double edge printing Probable Cause 8 em j Ink drying too fast Curl toward coated side Curl away from coated side Poor molds and plates Excessive plate pressure Viscosity too low Contamination of primary colors by any other color Two in line plates being inked from same area of the metering roll before re inking or the meeting roll can take place Improperly cleaned metering roll Moisture or solvent trapped in rewound roll and migrated onto the back of the wrap of film Excess pressure between plate and material Poor plates or makeready Cupped edges of plate Plate cylinder running out of Round Plate durometer too hard 2 1 Suggested Remedy Use slower solvent Speed up press Excessive moisture Introduce heat edges Use heat guns Lack of moisture Introduce moisture to edges Use moist sponge Prepare molds to proper floor Print with kiss impression Use compressible stickyback Raise viscosity Replace with pure transparent process colors Change diameter of plate cylinder or change speed differential of fountain roll to metering roll Thorough cleaning with proper brush Adequate solvent removal drying and reduced tension Reset plate pressure and ink viscosity Perform necessary makeready Make new plates and new plate mould avoid cupping Ch
5. PRESSROOM TROUBLESHOOTING CHART Adhesion poor ink Bleed Blocking Ink fails to adhere to material Fails tape test Fails crinkle test Fails scuff test An undercolor wetting into an overcolor Diffused or migrating colors Undesired adhesion two web surfaces 1 Improper ink formula 2 Ink thinned too much destroyed 3 Insufficient heat too low web temperature 4 Lack of treatment of some materials 5 Surface of stock may be contaminated 1 Undercolor drying too slowly or overcolor drying too fast 2 Effect of some stocks or materials on dye stuffs 1 Improper ink drying 2 trapped solvents 3 Excessive pressure in rewind 4 Softening of preapplied coatings 5 Web rewound too warm 6 Web rewound with excess surface moisture 1 Make certain you have the correct ink for the kind and grade of stock being run 2 Restore and hold ink 3 viscosity at optimum point Add fresh ink or resin binder Increase heat and or air volume 4 Check surface of the adequate treatment 5 Check with supplier check advisability and effectiveness of applying washcoat before printing 1 Use faster or slower preceding colors must be dry enough to receive subsequent colors laid down 2 Avoid use of dye colorants when unknown plasticizers are likely to be involved 1 Proper solvent balance 2 effective drying system or solvent balance 3 Reduc
6. arly Select anilox roll with lower cell volume or ink carrying capacity Add fresh ink and bring to proper viscosity Adjust roller nip to allow more ink on metering roll Consult roller manufacturer for proper specification for printing on given materials Replace with new or re engraved roll Thoroughly mix ink from container before adding to fountain Add pigment concentrate toner Add fresh ink and bring to proper viscosity Add varnish to increase tack Remake plates if mottled appearance is evident on surface Also examine plate mold for same mottle pattern Check wear condition of anilox lands Replace anilox roll 6 PRESSROOM TROUBLESHOOTING CHART Continued Defects Misregister Moire How Recognized 4 10 One part of design 1 not correctly positioned with another 2 Undesirable dot 1 pattern in process Printing Probable Cause Foreign matter on surface of plates Dirty or pitted impression cylinders Unevenly absorptive materials Uneven surface materials Ink starvation from anilox Contaminated Ink Ink lacks proper flow 10 Incorrect plate up plates not mounted in register Incorrect web tensions Incorrect draw roll adjustment Excessive web temperatures Failure to center press register compensators before putting job in press Idle rolls dragging or running intermitte
7. aterial some materials supplier 2 Failure of ink to form 2 Increase ink film thickness continuous ink film check impression anilox roll laydown to plate and plate to stock add impression if setting is too light Add pinhole compound to ink If 2 or 3 fails to correct condition call your inkmaker PRESSROOM TROUBLESHOOTING CHART Continued 8 Defects Plate swelling Poor ink Transfer Screening Skip print How Recognized Dimensionally larger softer than when mounted on cylinder Insufficient ink being applied to stock A definite pattern of small holes appearing in surface of solid Areas of plate failing to print Probable Cause Dirt on impression cylinder Ink drying too fast Worn anilox Ink or solvents not compatible with printing plates Ink reduced too much Ink drying on plates Surface of stock not receptive to ink Improper pressure among ink roller transfer roller and plate Ink drying too fast on anilox roll and failing to to transfer properly to printing plate Worn anilox roll Poor plates or makeready Impressions set to light Suggested Remedy 3 Clean impression cylinders 4 Use slower solvent or speed up press 5 Examine wear condition of anilox lands replace with new or reengraved roll 1 Check ink and solvents being used with your inkmaker and plate supplier 1 Rebuild tack and color stre
8. e rewind tension 4 Use solvents that do not attack prior coatings 5 Reduce web temperature by chilling within 10 0F of room temperature or reducing dryer temperature 6 Avoid rewinding excess surface moisture into finished roll Avoid overchilling that condenses moisture on web prior to rewind Brittleness Chatter Drying to Fast 2 Table 13 1 PRESSROOM TROUBLESHOOTING CHART Continued How Recognized Stock or material that When flexed Parallel lines of misprint Ink drying on plates and or roller and and failing to transfer to substrate Drying too slow One color bleeding into another improper trapping ink pickoff or transfer to press rollers and or plates Ink offset or blocking Probably Cause 6 Web rewound with excess surface moisture Excess heat in drying system causing release of moisture and plasticizer from paper or film Gear bottoming below pitch line 1 Improper use of solvents 2 Uncontrolled or unrestricted air movement in the in the vicinity of plates and rollers 3 Failure to use fountain covers 4 Improper ink for material 5 Dried ink on plates from start up 1 Use of improper solvents 2 Ink viscosity too heavy 3 Inadequate or unbalanced drying system Suggested Remedy 6 Avoid rewinding excess surface moisture into finished roll Avoid overchilling that condenses moisture on web prior to rewind 1 Control web or
9. eck plate cylinder shafts and journals and gears for run out Use recommended rubber plates For printing given materials 5 PRESSROOM TROUBLESHOOTING CHART Continued Defects How recognized Ink heavy Excess ink on anilox Strong roll or plates Ink weak thin Lacking color strength Ink mottling Spotted or speckled appearance of solid print Dark or colored intermittent streaks usually in a light color 1 Probable Cause Stickyback too thin and too firm Insufficient solvent and or high viscosity Improper setting of ink Roller nip Improper ink rollers for ink transfer Solvent imbalance Anilox doctor blade improperly set Improper anilox Too much solvent or viscosity too low Improper setting of ink roller nip Improper ink rollers for ink transfer Worn anilox roll Ink settled Excess extender varnish Ink too weak or too thin and loss of tack Surface of plates uneven Anilox roll cell walls too wide Suggested Remedy Use compressible stickyback Reduce ink to proper viscosity Properly adjust roller nip Increase or decrease nip pressure Consult roller manufacturer for proper specification for printing on given materials and type of printing to be processed Consult your ink formulator for optimum make up solvent mixture Adjust doctor blade to shave meeting roll more cle
10. irable odor in 1 Retained solvents 1 Balance solvents and check for Printed substrate proper solvent 2 Check dryer efficiency and Temperature w Increase between color drying 4 Reduce line speed Offset Transfer of ink to 1 Ink not dry at rewind 1 Use faster solvents Check Or set off opposite side of between color and final dryers material than that on for obstructions and adequate air which it was printed and temperature Reduce ink viscosity to minimum acceptable increase wipe between the fountain and anilox rolls 2 Trapped Solvents 2 Same as above Reduce ink film to minimum acceptable 3 Excess pressure in roll 3 Reduce rewind tension 4 Film treated on both sides 4 Avoid excess pressure in rewound for printing so that ink rolls Apply offset powder to web contacts opposite before rewinding overprint with treated surface such as nonblocking varnish if necessary 5 Films with plasticizers 5 Same as remedy number 4 subject to migration such as some vinyl film Pickoff First down ink 1 First color too slow 1 Add fast solvent to first color Ink transferring to increase between color dryer Subsequent plates temperature 2 Second color too fast 2 Add slow solvent to overprinting color Check dryer 3 Second down color too 3 Increase press operating speed high in viscosity and or reduce viscosity of second down color Pinholing Small holes in 1 Physical surface of 1 Consult your m
11. ngth by addition of fresh ink or extender or both 2 See defect Drying too fast Retard drying with slower drying solvent or thinner consult inkmaker 3 Verify ink formulation with ink supplier for given material check for souring add anti pinhole compound check stock for treatment 4 Adjust pressure 1 Use fountain covers retard drying speed of of ink Adjust exhaust on between color dryers 2 Examine wear condition of anilox lands Replace with new or reengraved anilox 1 Check impressions to determine accuracy of plates Secure new plates or do necessary makeready 2 Readjust impression settings Defects Souring ink Separation Or kick out Streaks or Smears Streaks in web direction Web Weave 9 Table 13 1 PRESSROOM TROUBLESHOOTING CHART continued How Recognized Thixatropic loss Of flow curdling Curdling and thixatropic much Like souring Blobs of lighter or darker Color in unwanted Areas on web Continuous dark lines through print Web failing to track or follow a true course through the press Probable Cause 3 Failure to lock down deck 4 Plate cylinder bounce Excessive moisture in ink due to Humidity Presence of wrong solvent or excessive diluent Gel particles are undissolved Uneven plates Foam bubbles being printed Ink splash dripping onto web Damaged fountain or anilox roll
12. ntly Press out of line Gauge variations in stock Anilox screen count too similar to plate screen count for instance a 165 line anilox plate can cause moire because of harmonic 85 x 2 170 too close to 165 line Improper screen angles Suggested Remedy 4 Wash plates thoroughly 5 Clean impression cylinders thoroughly of all foreign matter inks waxes etc 6 Softer plates sometimes may help more opaque ink may help 7 Softer plates should be tried 8 Adjust with richer or slower drying solvent 9 Clean and strain ink or replace with fresh ink Consult ink supplier for reformulation Study plate up mounting and makeready procedures 2 Study procedures involving auxiliary equipment P I V speed variators unwind and rewind tension controls 3 Check draw roll parallel constant side to side pressure centre wear condition 4 Reduce dryer temperatures 5 Center forward backward and side register compensators before manually keying in job register 6 Free all idle rolls so that they turn Freely mechanically Drive at web speed if necessary 7 Check and record press alignment 1 Change anilox Select a screen count appropriate for tone work Refer to chapter 14 on process printing 2 Refer to chapter on process for Proper screen angles 7 PRESSROOM TROUBLESHOOTING CHART Continued Defects How Recognized Probable Cause Suggested Remedy Odor Undes
13. rement from the end of the respective shafts 6 Gauge problems with 6 Replace roll of stock with new roll Wrinkling Wrinkles in 1 Baggy substrate 1 Tape rollers at web edge substrate to draw out wrinkles 2 Equipment misalignment 2 Adjust all roller alignment
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