The relationship between flexible printing failure and printing plate The flexographic printing method develops rapidly in China, and the technical capabilities of various manufacturers are uneven. Various problems often occur in the printing process. This article is a summary of the experience of a flexo professional and technical staff in handling customer complaints, and is now shared with everyone....

Case 1: Paste/blocking, phenomenon: the side of the printing plate is sticky or the word groove is blocked.

the reason:

A ink distribution is uniform, it is recommended to use a good dispersion of ink.

There are impurities in the B ink. It is recommended to filter the ink.

C text, graphics and dots are not suitable for printing. Recommendation: Consider the printing capabilities of the press and redesign.

D ink fountain roller pressure is not appropriate. Recommendation: Use reasonable pressure.

Between the anilox roller and the printing plate, the pressure between the printing plate and the substrate is not properly adjusted. It is recommended to adjust the pressure reasonably.

F The ink of other units is strung on the plate. Recommendation: Adjust the dry state and solvent volatility between the various color groups.

G ink has high viscosity and large amount of ink. Recommendation: Reduce the viscosity.

The H ink dries too quickly and blocks the plate groove. Recommendation: Properly add slow drying agent

Relationship with the plate:

1. The plate embossing is too shallow. Recommendation: It is best to use the halving method for the plate relief and the base. For example: KY394JM-A base 2.00MM.

2. The gap between the fonts is tight and the white is too shallow. Recommendation: Check the film blackness and reduce the main exposure time or make a partial plate mask.

Case 2: Graphic bleeding. Phenomenon: The pigment in the pattern is dissolved and diffused.

the reason:

A ink is poorly dried. Recommendation: Use a suitable solvent.

B is affected by plasticizers or fuels in the substrate. Recommendation: Avoid using fuel colorants.

C Ink stability (dispersed before printing). Recommendation: Mix well before using or replacing a more stable ink.

Relationship with the printing 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 solvent is not used properly. Recommendation: Use a suitable solvent to balance.

C is received in the hot roll state. Recommendation: Cool the print before the roll.

D winding pressure is too large. Recommendation: Reduce the winding pressure.

Relationship with the printing plate: None.

Case 4: Flossing, Phenomenon: Graphic has irregular edges

the reason:

A anilox roller and plate pressure is not appropriate. Recommendation: Adjust the pressure.

The B layout ink dries quickly. Recommendation: Cover the ink fountain and use the appropriate solvent.

C plate reuse is not clean. Recommendation: Wash the plate and reuse it.

D plate is destroyed when cleaning. Recommendation: Use a suitable cleaning agent.

E ink fountain roller pressure is not good. Recommendation: Adjust properly.

The F anilox roller does not match the plate. Recommendation: Replace the anilox roller or plate (depending on the print pattern).

G ink viscosity is not good. Recommendation: Replace the anilox roller.

The surface of the H substrate is rough. Recommendation: Replace the anilox roller.

Relationship with the plate:

1, the pattern is imaginary. Recommendation: If the film is qualified, increase the exposure time.

2. The plate is not sticky. Recommendation: Fully de-stick the plate.

Case 5: Lack of printing, phenomenon: thin lines and dot blots are not clear, there are white spots in the pattern, and the lines are curved.

the reason:

A embossing force is too light. Recommendation: Appropriately increase the pressure.

B press is poorly adjusted. Recommendation: Adjust the printing mechanism to make it work in balance.

C plate scrolling. Recommendation: Check the ovality of the plate cylinder and gear.

D The amount of ink transferred is too large. Recommendation: Control the amount of ink transferred.

E ink has a high viscosity. Recommendation: Properly reduce ink viscosity.

F printing double-sided adhesive thickness is uneven or there are bubbles when the version is installed.

G printing dots are missing / lines are bent. Recommendation: Consider the compatibility of the ink solvent with the plate.

Relationship with the plate:

1, the printing plate is awkward. Recommendation: Check if the film is qualified or enhances exposure time.

2. The thickness of the plate is not uniform. Recommendation: Use a qualified media.

3. The washing time is too long or the brush is too hard. Recommendation: Replace the used brush with the appropriate plate wash time.

4, the hardness of the printing plate. Recommendation: A dot print on thin lines, using a higher hardness, for example: KY394JM-AShoreA38° (for carton printing). B uses a resilient pad. C uses a more flexible double-sided tape.

Case 6: Foaming. Phenomenon: The ink is foaming.

the reason:

For the internal friction of A ink, it is recommended to use a suitable defoamer.

B ink roller pressure is equal to the circumferential speed of the anilox roller, it is recommended to reduce the speed ratio of the two.

There are excessive fluctuations in the C ink cycle. It is recommended to check the oil pump impeller and gear.

Relationship with the printing plate: None.

Case 7: The print is brittle. Phenomenon: The printed surface is damaged when bent.

the reason:

The high heat in the drying system reduces the moisture and plasticizer in the substrate.

Recommendations: 1. Control the temperature of the coil. 2. Supply water vapor after drying. 3. The substrate passes through the wetting chamber.

Relationship with the printing 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:

A ink transfer system has poor ink transfer and low ink transfer. It is recommended to increase the ink flow rate appropriately.

Excessive use of B defoamer, it is recommended to use defoamer properly.

Relationship with the printing plate: None.

Case 9: Pattern overprinting is not allowed. Phenomenon: The printed pattern is misplaced and the level is not clear.

the reason:

The thickness of the A-loaded tape is inconsistent. It is recommended to use double-sided tape of uniform thickness.

The diameter of the B plate is different. It is recommended to check whether the diameter of the plate is the same.

C loading technology is poor, it is recommended: pay attention to the security school position.

D substrate stretch / shrink, it is recommended: pay attention to the material removal mechanism and temperature.

E bearing body is dirty and worn. It is recommended to clean the bearing and replace the bearing with large wear.

Relationship with the plate:

A version of the film is not registered, it is recommended to: correct the film alignment.

The thickness of the B version is inconsistent. It is recommended to use the same brand and the same type of plate.

C plate drying temperature is high and there is no reply. It is recommended to use a temperature of about 65 °C to dry and then dry for a period of time to allow the plate to resume and continue the plate making process.

When making a plate, consider the length of each plate making time. It is recommended to determine whether the main exposure time is appropriately lengthened according to the graphic distribution.

Case 10: Poor ink coverage, phenomenon: spots and strips.

the reason:

A ink viscosity is low, it is recommended to: properly increase the viscosity of the ink.

B ink drying too fast, it is recommended to add slow dry agent.

C Quantitative roller damage, it is recommended to replace the dosing roller.

D Anilox roller is damaged, it is recommended to replace the anilox roller.

E scraper wear, it is recommended to increase the ink flow.

There are impurities and oil stains on the G substrate. It is recommended to check the substrate.

Relationship with the plate:

A plate is too sticky, it is recommended to control the time to remove the glue.

B version cleaning / wiping bad, it is recommended: clean the layout (with residue), replace the washing water.

Case 11: There is no part of the pattern printed.

the reason:

A version is too loose, it is recommended: the version is tight.

B stickers have bubbles or dirt underneath. It is recommended to wipe the back of the plate and the base of the plate when applying the plate and pay attention to the bubble problem.

C-hanging film base has deformation phenomenon, it is recommended to use a stable quality of the hanging glue.

D tape is poorly viscous, it is recommended to use a more adhesive double-sided tape.

E printing pressure is too large, it is recommended to: properly reduce the pressure.

F ink drying too fast, it is recommended to add slow drying agent to the ink.

G paper, dust, dirt, suggestion: check the substrate.

Relationship with the plate:

A negative film density is low, it is recommended to use a reasonable negative film density.

B is too shallow, it is recommended to reduce back exposure.

C Washing time is insufficient / brush pressure is not enough, it is recommended to adjust the brush distance and use a reasonable plate washing time.

Case 12: There are stripes at the beginning and end of the picture. Phenomenon: warping.

the reason:

A has no edge banding. It is recommended to pay attention to the edge of the plate when attaching or adding edge sealant.

B-loaded tape is not sticky enough. It is recommended to pay attention to the stickiness of the adhesive tape.

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