Questions |
Check programme |
Causes |
Answers |
Exposure
virtuality
(halation)
|
Exposure operation |
Plate rumple |
Be careful to improve ways of holding plates.Enforcement should meet natural strain and straight. |
Exposure |
Light source is too near to the plate |
Adjust the distance between light source and plates higher than the plate diagonal. |
Exposure |
Dirt on the film and the exposure glass. |
Clean film and glass with clean soft cloth and glass cleaner.Reduce the stains and spots on the exposure glass as much as possible. |
Exposure
imbalance |
Exposure |
Light source is too near to the plate |
Adjust the distance between light source and plates higher than the plate diagonal. |
Exposure |
Light source is not placed correctly |
Place the light source correctly.Put the plate right under the light source. |
Image defects |
Exposure |
Spots on the exposure glass in the exposure frame |
Clean film and exposure glass with clean cloth and glass cleaner.Reduce spots on the glass as much as possible. |
Low run length |
Exposure |
Underexpose negative plate |
Check the solid steps after the plate is exposed through gray scale.Increase exposure. |
Development |
Overdevelop |
Check the dilution of the developer,developing temperature and developing time. |
Adjust printing pressure,roller pressure |
Pressure between plate cylinder and blanket cylinder is too high. |
Decrease plate cylinder-blanket cylinder pressure and check regularly. |
Blanket |
Elasticity of the blanket becomes worse |
Replace blanket |
Operation |
Overexpose the positive plate |
Check the clear steps after the plate is exposed,Reduce exposure |
Fountain solution |
Concentration change of fountain solution |
Use fountain solution replenishment equipment |
Ink shortage |
Gumming |
Gum solution is too thick or coating is not uniform |
Dilute the gum solution or adjust coating method of gum solution to make gum coating uniform |
Baking |
Baking solution is too thick |
Coat the baking solution uniformly on the plate surface with sponge. |
| Adjust printing pressure |
The pressure between the plate cylinder and blanket cylinder or the pressure between the printing cylinder and blanket cylinder is too low. |
Increase the pressure between the plate cylinder and blanket cylinder and the pressure between the printing cylinder and blanket cylinder and check regularly. |
The contact pressure between plate cylinder and ink roller is too low. |
Increase the contact pressure between plate cylinder and ink roller.Check regularly. |
The contact pressure between fountain roller is not right |
Adjust the contact pressure between fountain rollers. |
Blanket |
Rough,deformed |
Check regularly and recover well. |
Fountain solution |
Fountain solution is too much. |
Adjust the contact pressure between fountain rollers. |
Dot gain |
Exposure |
Overexpose(negative)
Underexpose(positive)
|
Check exposure |
Development |
Underexpose(positive) |
Check the concentration,temperature of developer and developing time. |
Adjustment of printing pressure |
The pressure between plate cylinder and blanket cylinder or between printing cylinder and blanket cylinder is too high. |
Check the print pressure regularly. |
Adjust the ink in the in filler |
Accepting ink is too much |
Reduce the ink on the roller |
Fountain solution |
Ink is over-emusified |
Check fountain solution |
Dot loss |
Exposure |
Overexpose(positive) |
Check the clear steps of gray scale |
Development |
Overexpose(positive) |
Develop under the control of gray scale.Check the develop activity. |
Adjust printing pressure |
The pressure between plate cylinder and blanket cylinder or between printing cylinder and blanket cylinder is too low. |
Check the pressure between plate cylinder and blanket cylinder or printing cylinder and between printing cylinder and blanket cylinder. |
Plate contamination |
Fountain solution |
Fountain solution is not enough |
Increase the amounts of fountain solution. |
Scum |
Exposure |
Exposure time is too long (negative). |
Check the solid steps. |
| Under-exposure (positive). |
Check the clear steps. |
| Development |
Under-exposure (positive). |
Develop under the control of gray scale and check developer activty. |
| Retouchment |
Image remover is not removed compeletely. |
Rinse and remove the image remover after retouchment. |
| No gumming |
Gumming gum solution. |
| Gumming |
Gum solution is diluted too much. |
Concentrate gum solution. |
| Baking |
Baking solution is too thin. |
Adjust the coating weight of baking solution. |
| Adjustment of printing pressure |
The contact pressure between ink rollers is too high |
Decrease the contact pressure between ink rollers and check regularly. |
| Fountain solution |
Fountain solution is deficient |
Increase the amounts of fountain solution. |
| The concentration of fountain solution is too low |
Increase the concentration of fountain solution. |
| Rubber cover is aging |
Replace the rubber cover. |
| Ink in the filler |
Accepting ink is too much. |
Reduce ink on the ink roller. |
| Printing plate is starting |
Plate scratch,fingerprint,spots |
After cleaning the plates with cleaner for plates,wipe plate surface well immediately . |
| Blanket in transfer |
Blanket is aging |
Replace blanket |
| Ink color |
Adjust roller pressure |
The roller is aging |
Check the roller pressure regularly |
| The amounts of fountain solution |
Over-emusified ink |
Check fountain solution |
| Double image |
Adjust roller pressure |
The pressure of fountain water rollers is not right |
Check the roller pressure regularly |
| Fountain solution |
Fountain solution is too much |
Reduce fountain solution. |
| Ink color is too light |
Fountain solution |
Ink is over-emusified.Fountain solution is too much |
Reduce fountain solution and check fountain solution |
