The flexographic printing method has developed rapidly in China, and the corresponding theoretical basis is relatively weak. Various problems and phenomena occur in the printing process. I make a KY flexo supplier technical staff, and often go to the factory technical service, for the printing process. In the event of a failure, there are always complaints of "uncertainty" and "unclear responsibility": (print making, ink supply, paper defects, etc.) Therefore, I made some expositions on the relationship between flexographic printing faults and processing and printing plates, and exchanged and negotiated with the printing industry.
Case 1: Paste/blocked version, phenomenon: The printed image has more ink stuck on the side of the image or the word groove is blocked.
the reason:
A evenly distributed ink, it is recommended: use good ink dispersion.
B Ink contains impurities, it is recommended: filter ink.
C text, patterns, and dots are not suitable for printing. Recommendation: Consider the printing capabilities of the press and redesign.
D Ink roller pressure is improper. Recommendation: Use reasonable pressure.
E Between the anilox roller and the printing plate, the pressure adjustment between the printing plate and the substrate is not proper. It is recommended that: reasonably adjust the pressure.
F. The ink string of the other unit is on the plate. Advice: Adjust the dryness and solvent volatility between color groups.
G ink has a high viscosity and a large amount of ink. Recommendation: Lower the viscosity.
The H ink dries too quickly, blocking the plate groove. Recommendation: Add Slow Drying Agent Properly
The relationship with the plate:
1, plate embossed too shallow. Recommendation: It is best to use a bisecting method for the printing plate relief and substrate. For example: KY394JM-A base 2.00MM.
2. The spaces between the fonts are tight and white. Advice: Check the darkness of the film and reduce the main exposure time or make part of the plate mask.
Case II: Graphic bleeding. Phenomenon: The pigment in the pattern is dissolved for diffusion flow.
the reason:
A ink is poorly dried. Recommendation: Use an appropriate solvent.
B is affected by the plasticizer or fuel in the printing material. Recommendation: Avoid using fuel colorants.
C ink stability (dispersed before printing). Suggestion: Stir thoroughly before use or replace the ink with strong stability.
Relationship with the plate: None.
Case 3: Adhesion, Phenomenon: The two surfaces adhere to each other (dirty)
the reason:
A ink is poorly dried. Recommendation: Use a complete drying system.
B. Improper use of solvent. Recommendation: Use an appropriate solvent to balance.
C receives the material in hot rolled condition. Recommendation: Cool the print before coiling.
D overwhelming pressure. Recommendation: Reduce rewind pressure.
Relationship with the plate: None.
Case 4: Fleeting, Phenomenon: Graphic with irregular flash
A Anilox roller and plate pressure are not proper. Advice: Adjust pressure.
The B layout ink dries quickly. Suggestion: The ink fountain is capped and the appropriate solvent is used.
C plate reuse is not clean. Recommendation: Wash the plate and use it again.
Destruction of D plate cleaning. Recommendation: Use an appropriate cleaning agent.
E Ink roller pressure is improper. Recommendation: Adjust properly.
F Anilox roller does not match the plate. Recommendation: Replace the anilox roll or plate (depending on the print pattern).
G ink viscosity is not proper. Recommendation: Replace the anilox roller.
The surface of the H printing material is rough. Recommendation: Replace the anilox roller.
Relationship with the plate:
1, the pattern is made virtual. Recommendation: Whether the film is qualified or not, increase the exposure time.
2, improper printing plate to stick. Advice: Adhere to the plate fully.
Case 5: Out of Print, Phenomenon: Thin lines and dot blots are unclear, white dots in the pattern, and curved lines.
the reason:
A stamping force is too light. Advice: Increase stress properly.
B printer is poorly adjusted. Recommendation: Adjust the printing mechanism so that it is balanced.
C plate scroll jump. Recommendation: Check the ovality of the plate cylinder and gear.
D has a large amount of ink. Recommendation: Control the amount of ink transferred.
E ink viscosity. Recommendation: Reduce ink viscosity properly.
F printing double-sided adhesive uneven thickness or air bubbles when installed.
G missing print dots/curved lines. Recommendation: Consider ink solvent compatibility with plate.
Relationship with the plate:
1. The printing plate is shown to be false. Recommendation: Check the film for eligibility or enhanced exposure time.
2. The thickness of the plate is not uniform. Recommendation: Use a qualified plate.
3, wash version is too long or brush too hard. Suggestion: Use appropriate wash time and replace the brushes used.
4, the hardness of the plate. Suggestion: A dot fine line printing, using a higher hardness, such as: KY394JM-A ShoreA38 ° (for carton printing). B uses a resilient pad. C uses a more flexible double-sided adhesive.
Case 6: Foaming. Phenomenon: The ink is blistering.
the reason:
A internal friction of the ink, it is recommended to use an appropriate defoamer.
B. The ink fountain roller pressure is equal to the anilox roller peripheral speed. It is recommended to reduce the speed ratio of the two.
C There is excessive fluctuation in the ink circulation. It is recommended to check the oil pump impeller and gear.
Relationship with the plate: None.
Case 7: Brittle print. Phenomenon: The printed surface is broken when bent.
the reason:
High heat in the drying system reduces moisture and plasticizers in the substrate.
Suggestions: 1. Control the temperature of the coil. 2. Supply water vapor after drying. 3. The substrate passes through the wetting chamber.
Relationship with the plate: None.
Case 8: When the ink is covered, it is light and heavy. Phenomenon: There are vertical stripes on the printed pattern.
the reason:
The A-ink transfer system has poor ink transmission and low ink transfer. It is recommended that the ink flow be increased appropriately.
B excessive use of defoamer, it is recommended: the rational use of defoamers.
Relationship with the plate: None.
Case 9: Pattern overprinting is not allowed. Phenomenon: Dislocations and levels of printing patterns are not clear.
the reason:
The thickness of the A-size tape is inconsistent. It is recommended to use a double-sided tape with the same thickness.
B version of the roller diameter is different, it is recommended: Check the version so the diameter is the same.
C is poor in loading technology. It is recommended to pay attention to the safety printing school.
D. The substrate is stretched/contracted. It is recommended: Pay attention to the feeding mechanism and temperature.
E The bearing body is dirty and worn. It is recommended that: Clean the bearings and replace the more worn bearings.
Relationship with the plate:
A plate-making film does not register, it is recommended: correct film alignment.
The thickness of version B is inconsistent. It is recommended that the same brand and the same type of material be used.
C plate drying temperature is high and there is no reply, it is recommended: Use a temperature of about 65 °C baking and drying and then left at room temperature for a period of time to allow the plate to resume the plate-making process.
When considering the length of the plate making process for each color, it is recommended to: Determine whether the main exposure time should be lengthened appropriately according to the graphic distribution.
Case 10: Poor ink coverage, phenomenon: spots and stripes.
the reason:
A ink viscosity is low, it is recommended: properly increase the viscosity of the ink.
B. The ink is drying too fast. It is advisable to add a slow drying agent as appropriate.
C. The sizing roller is damaged. Recommendation: Replace the metering roller.
D The anilox roll is damaged. It is recommended to replace the anilox roll.
E blade wear, it is recommended: increase the ink flow.
G The substrate has impurities, oil stains, etc. It is advisable to check the substrate.
Relationship with the plate:
A plate is too sticky, it is recommended: to control the de-bonding time.
B version cleaning / wiping bad, it is recommended: clean the layout (with residue), replace the wash water.
Case 11: Something printed without a pattern.
the reason:
A version is too loose, it is recommended: tight version.
There are bubbles or dirt on the bottom of the B version. It is recommended to clean the back of the plate and the base of the attached plate when attaching the plate and pay attention to the air bubble problem.
There are deformations on the base of the C-hanging plate. It is recommended that: the use of a stable-quality platen glue.
D tape has poor adhesiveness. It is recommended to use a more adhesive double-sided tape.
E Printing pressure is too high, it is recommended: reduce the pressure properly.
The F ink dries too quickly. It is recommended that slow drying agents be added to the ink.
G Paper, dust, dirt, advice: Check the substrate.
Relationship with the plate:
A negative film density is low, it is recommended: use a reasonable negative film density.
B printed too shallow, it is recommended: reduce back exposure.
C. Insufficient washing time/brush pressure is not enough. It is recommended to adjust the brush distance and use reasonable washing time.
Case 12: Stripes appear in the head and tail of the picture. Phenomenon: Alice.
the reason:
A has no edge banding. It is recommended that you stick to the edge or seal the edge when sticking.
B adhesive tape is not sticky, it is recommended: pay attention to adhesive tape stickiness.
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Case 1: Paste/blocked version, phenomenon: The printed image has more ink stuck on the side of the image or the word groove is blocked.
the reason:
A evenly distributed ink, it is recommended: use good ink dispersion.
B Ink contains impurities, it is recommended: filter ink.
C text, patterns, and dots are not suitable for printing. Recommendation: Consider the printing capabilities of the press and redesign.
D Ink roller pressure is improper. Recommendation: Use reasonable pressure.
E Between the anilox roller and the printing plate, the pressure adjustment between the printing plate and the substrate is not proper. It is recommended that: reasonably adjust the pressure.
F. The ink string of the other unit is on the plate. Advice: Adjust the dryness and solvent volatility between color groups.
G ink has a high viscosity and a large amount of ink. Recommendation: Lower the viscosity.
The H ink dries too quickly, blocking the plate groove. Recommendation: Add Slow Drying Agent Properly
The relationship with the plate:
1, plate embossed too shallow. Recommendation: It is best to use a bisecting method for the printing plate relief and substrate. For example: KY394JM-A base 2.00MM.
2. The spaces between the fonts are tight and white. Advice: Check the darkness of the film and reduce the main exposure time or make part of the plate mask.
Case II: Graphic bleeding. Phenomenon: The pigment in the pattern is dissolved for diffusion flow.
the reason:
A ink is poorly dried. Recommendation: Use an appropriate solvent.
B is affected by the plasticizer or fuel in the printing material. Recommendation: Avoid using fuel colorants.
C ink stability (dispersed before printing). Suggestion: Stir thoroughly before use or replace the ink with strong stability.
Relationship with the plate: None.
Case 3: Adhesion, Phenomenon: The two surfaces adhere to each other (dirty)
the reason:
A ink is poorly dried. Recommendation: Use a complete drying system.
B. Improper use of solvent. Recommendation: Use an appropriate solvent to balance.
C receives the material in hot rolled condition. Recommendation: Cool the print before coiling.
D overwhelming pressure. Recommendation: Reduce rewind pressure.
Relationship with the plate: None.
Case 4: Fleeting, Phenomenon: Graphic with irregular flash
A Anilox roller and plate pressure are not proper. Advice: Adjust pressure.
The B layout ink dries quickly. Suggestion: The ink fountain is capped and the appropriate solvent is used.
C plate reuse is not clean. Recommendation: Wash the plate and use it again.
Destruction of D plate cleaning. Recommendation: Use an appropriate cleaning agent.
E Ink roller pressure is improper. Recommendation: Adjust properly.
F Anilox roller does not match the plate. Recommendation: Replace the anilox roll or plate (depending on the print pattern).
G ink viscosity is not proper. Recommendation: Replace the anilox roller.
The surface of the H printing material is rough. Recommendation: Replace the anilox roller.
Relationship with the plate:
1, the pattern is made virtual. Recommendation: Whether the film is qualified or not, increase the exposure time.
2, improper printing plate to stick. Advice: Adhere to the plate fully.
Case 5: Out of Print, Phenomenon: Thin lines and dot blots are unclear, white dots in the pattern, and curved lines.
the reason:
A stamping force is too light. Advice: Increase stress properly.
B printer is poorly adjusted. Recommendation: Adjust the printing mechanism so that it is balanced.
C plate scroll jump. Recommendation: Check the ovality of the plate cylinder and gear.
D has a large amount of ink. Recommendation: Control the amount of ink transferred.
E ink viscosity. Recommendation: Reduce ink viscosity properly.
F printing double-sided adhesive uneven thickness or air bubbles when installed.
G missing print dots/curved lines. Recommendation: Consider ink solvent compatibility with plate.
Relationship with the plate:
1. The printing plate is shown to be false. Recommendation: Check the film for eligibility or enhanced exposure time.
2. The thickness of the plate is not uniform. Recommendation: Use a qualified plate.
3, wash version is too long or brush too hard. Suggestion: Use appropriate wash time and replace the brushes used.
4, the hardness of the plate. Suggestion: A dot fine line printing, using a higher hardness, such as: KY394JM-A ShoreA38 ° (for carton printing). B uses a resilient pad. C uses a more flexible double-sided adhesive.
Case 6: Foaming. Phenomenon: The ink is blistering.
the reason:
A internal friction of the ink, it is recommended to use an appropriate defoamer.
B. The ink fountain roller pressure is equal to the anilox roller peripheral speed. It is recommended to reduce the speed ratio of the two.
C There is excessive fluctuation in the ink circulation. It is recommended to check the oil pump impeller and gear.
Relationship with the plate: None.
Case 7: Brittle print. Phenomenon: The printed surface is broken when bent.
the reason:
High heat in the drying system reduces moisture and plasticizers in the substrate.
Suggestions: 1. Control the temperature of the coil. 2. Supply water vapor after drying. 3. The substrate passes through the wetting chamber.
Relationship with the plate: None.
Case 8: When the ink is covered, it is light and heavy. Phenomenon: There are vertical stripes on the printed pattern.
the reason:
The A-ink transfer system has poor ink transmission and low ink transfer. It is recommended that the ink flow be increased appropriately.
B excessive use of defoamer, it is recommended: the rational use of defoamers.
Relationship with the plate: None.
Case 9: Pattern overprinting is not allowed. Phenomenon: Dislocations and levels of printing patterns are not clear.
the reason:
The thickness of the A-size tape is inconsistent. It is recommended to use a double-sided tape with the same thickness.
B version of the roller diameter is different, it is recommended: Check the version so the diameter is the same.
C is poor in loading technology. It is recommended to pay attention to the safety printing school.
D. The substrate is stretched/contracted. It is recommended: Pay attention to the feeding mechanism and temperature.
E The bearing body is dirty and worn. It is recommended that: Clean the bearings and replace the more worn bearings.
Relationship with the plate:
A plate-making film does not register, it is recommended: correct film alignment.
The thickness of version B is inconsistent. It is recommended that the same brand and the same type of material be used.
C plate drying temperature is high and there is no reply, it is recommended: Use a temperature of about 65 °C baking and drying and then left at room temperature for a period of time to allow the plate to resume the plate-making process.
When considering the length of the plate making process for each color, it is recommended to: Determine whether the main exposure time should be lengthened appropriately according to the graphic distribution.
Case 10: Poor ink coverage, phenomenon: spots and stripes.
the reason:
A ink viscosity is low, it is recommended: properly increase the viscosity of the ink.
B. The ink is drying too fast. It is advisable to add a slow drying agent as appropriate.
C. The sizing roller is damaged. Recommendation: Replace the metering roller.
D The anilox roll is damaged. It is recommended to replace the anilox roll.
E blade wear, it is recommended: increase the ink flow.
G The substrate has impurities, oil stains, etc. It is advisable to check the substrate.
Relationship with the plate:
A plate is too sticky, it is recommended: to control the de-bonding time.
B version cleaning / wiping bad, it is recommended: clean the layout (with residue), replace the wash water.
Case 11: Something printed without a pattern.
the reason:
A version is too loose, it is recommended: tight version.
There are bubbles or dirt on the bottom of the B version. It is recommended to clean the back of the plate and the base of the attached plate when attaching the plate and pay attention to the air bubble problem.
There are deformations on the base of the C-hanging plate. It is recommended that: the use of a stable-quality platen glue.
D tape has poor adhesiveness. It is recommended to use a more adhesive double-sided tape.
E Printing pressure is too high, it is recommended: reduce the pressure properly.
The F ink dries too quickly. It is recommended that slow drying agents be added to the ink.
G Paper, dust, dirt, advice: Check the substrate.
Relationship with the plate:
A negative film density is low, it is recommended: use a reasonable negative film density.
B printed too shallow, it is recommended: reduce back exposure.
C. Insufficient washing time/brush pressure is not enough. It is recommended to adjust the brush distance and use reasonable washing time.
Case 12: Stripes appear in the head and tail of the picture. Phenomenon: Alice.
the reason:
A has no edge banding. It is recommended that you stick to the edge or seal the edge when sticking.
B adhesive tape is not sticky, it is recommended: pay attention to adhesive tape stickiness.
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