Causes and solutions of partial ghosting failure i

2022-08-09
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Causes and solutions of printing local ghosting fault

local ghosting is such an extension that the gauge held by the gauge is the original gauge of the sample in its free state. It is a common printing fault and one of the main reasons for defective products and waste products. Understanding the causes of local ghosting can help us solve the problem quickly

I. local ghosting caused by mechanical failure

gear wear, local damage to gears, large gear clearance, etc. will produce large vibration during pressure closing, resulting in local ghosting

II. Local ghosting caused by printing materials

1 Paper quality factor

if the filling material of the paper is unevenly distributed and the sizing is uneven, it will cause uneven thickness of the paper, and it is very easy to produce local ghosting during printing. The position of this ghosting is not fixed, sometimes absent, sometimes light and sometimes heavy. And in the printing process, there are often phenomena such as galling and powder dropping

2. The paper is not well preserved

because the temperature and humidity when the paper is stored cannot meet the requirements, the paper is deformed greatly, and local ghosting is easy to occur during printing. This ghosting spreads along the deformation direction of the paper, and the position is not fixed, sometimes not, sometimes light and sometimes heavy

the quality of paper is one of the important factors causing local ghosting. Therefore, when ghosting occurs, the paper factor should be considered first after eliminating the mechanical reasons

III. local ghosting caused by poor blanket and liner

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2) the blanket is not tight

the blanket is not tight, and the local ghosting produced is at the trailing tip, and the direction is fixed

3) the rubber blanket is not good, and the tension between the left and right is inconsistent

this phenomenon is generally due to the different lengths of both sides of the rubber blanket. After being installed, one side is tight, the other side is not tight, and the local ghost is on the side that is not tight

4) the blanket is damaged

the blanket has large indentation or cracks, which will produce local ghosting. If the damaged part is in the embossing area, it is easy to solve. However, if the damaged part is not in the embossing area, it is often difficult to judge

5) aging of rubber layout part

due to the erosion of some parts of the blanket by organic solvents, the eroded parts of the blanket lose their original elasticity and are prone to local ghosting

6) local ghosting produced when the printing paper is changed from small size to large size

this is because the original embossing area is under long-term stress, and its elastic deformation is inconsistent with the elastic deformation of the original non embossing area. However, this phenomenon generally disappears after being pressed for a period of time

2. Poor liner and liner paper produce local ghosting

1) the quality factor of the liner itself

uneven thickness of the liner will also produce ghosting, which is difficult for ordinary people to think of

2) the liner is damaged and deformed after long-term use

if the liner is replaced with a new blanket, local ghosting will occur during printing, and the liner factor should be considered first

3) the backing paper is wrinkled

the backing paper is not placed properly, causing the backing paper to wrinkle and local ghosting

3. There are foreign objects under the blanket and liner

which is also the main reason for local ghosting. Therefore, the operator should be careful when loading the blanket to avoid foreign matters remaining under the blanket or liner

IV. local ghosting caused by poor pad paper of the printing plate

local ghosting will also occur if the pad paper is not placed properly or there are foreign objects under the printing plate. If you carefully observe it with a magnifying glass, you will find that the point deformation is large

v. partial ghosting caused by tooth picking failure

1 The spring force of the gripper is inconsistent

due to the inconsistent gripper force on both sides of the gripper, the paper displaces or deforms during printing, resulting in local ghosting. The electronic and microcomputer controlled products launched by the factory are of different grades

2. Some teeth are blocked

1) when printing small-size paper for a long time, the teeth blocked by dust are not cleaned when changing to large-size paper, resulting in inconsistent teeth holding force and local ghosting

2) local ghosting may also occur if the teeth are not cleaned for a long time or some teeth are damaged

VI. other factors

1 Plate making factor

due to errors in plate making, local ghosting will be caused

2. The printing plate is not tensioned

the printing plate is not tensioned, causing displacement during printing, causing local ghosting

3. There is dirt on the impression cylinder

4. The paper is not in place, causing the paper to wrinkle

in short, there are many reasons for local ghosting, and more influencing factors need to be analyzed and summarized together

(Chen Min, Huai'an Press)

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