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PAD Knowledge
Pad printing is the technicality of using indirect elasticity Silicon printing pad. Now is the most popular printing method in surface printing .
A: Theorem
It is easy to operate. First, etching the designed pattern onto the steel plate. Spray on printing ink and use the Silicon printing pad to transfer the pattern onto the surface of the products.
B: Method of printing
There are several methods of spray printing ink on the steel plate. We will use a extendable doctor blade to scrape out the excess printing ink. The ink remained on the etched area in the steel plate now will be solidify. The printing pad will pick up the ink clot.
C: Pick up and print
The ink clot after pick up by the printing pad will evaporate, the remains will stick onto the surface of the article tensely. The shape of printing pad is designed specially that can exhale all the air between steel plate and pad by the action of press.
D: The matching of ink and pad in working procedure
There are several methods of spray printing ink on the steel plate.We will use a extendable doctor blade to scrape out the excess printing ink. The ink remained on the etched area in the steel plate now will be solidify. The printing pad will pick up the ink clot.
E: Etching steel plate
Mainly steel plate:
1. Thick steel plate
2. Steel strip
3. Plastic Film plate ( can exposure)
For all picture is used the photographic to make a film. We place the film on the developed steel plate and expose it under UV light. The plate without picture will become a protect layer, wash out the picture area (use water and alcohol mixture to wash plastic film plate). Raised to dry. The steel plate will put into hydrochloric acid for etching. This procedure must be work carefully. The production fixtures of this high quality steel plate etching system need about $3000, according to the demand of customer. Customer can choose the plate with their choice. Thick steel plate is the most suitable for production but the printing quality not as good as the other. Normality, steel strip will have a developer coating on it. It is easy to use. In the case of printing quality, plastic film plate is the best. But working procedure is the most difficult one. On the other way, the depth of etching and the quality of plate will influence the result of printing.
F: Silicon printing (transit) pad
Printing pad is made by elasticity silicon. Different shape of pad is act to pick up the ink clot from the picture on the plate and transit it to the different article. This action will influence by the following.
1. Shape of the pad
2. Hardness of the pad
3. Smooth surface of the pad
4. Material of the pad
Standard printing pad is circle, square and rectangle. Which shape of pad we should use is according to the size and shape of printing pattern . Ink transit effect is the best while the silicon pad is harder. And the hardness of the pad is influence by the adding of silicon oil. The ideal surface of the printing pad is smoothly and shiny. By using a cloth, fully with thinner to clean the surface of the pad. It will provide a good condition to work. After 50,000 times of working, we should be change a new pad carefully while the abrasion is appeared.
G: Ink
We should use the ink with a high contain of pigment. Quick to dry resin and the evaporation of the thinner is quick. There are several kinds of ink of customer to choose for printing on different material. In pad printing, the use of ink is low but the price of ink is high. Therefore the ink for screen printing is not suitable for pad printing because its ink is not easy to dry and the contain of pigment is only 5 %.
H: Sealed ink cup printer
There is another choice of sealed ink cup printer instead of open ink tray printer. The ink is stored in the ink cup after scrape from the steel plate by the doctor blade. Because the ink cup is sealed, the solvent can’t be evaporated. The ink will keep in the most stable condition for long time working. Operate of ink must be pretty serious. Otherwise we need to change a new ink tray with the expensive cost due to the careless.
I. Main points of pad printing
From film to etching steel plate:Use the film to exposure with the pattern onto the developed steel plate. After etching, a steel plate can be used for pad printing.
From silicon pad to steel plate:This time the silicon pad will press on the steel plate and pick up the ink clot create on the steel plate while raising up.
From silicon pad to article:Silicon pad press on the article, the ink clot will stick on the surface of product.
From silicon pad to release article:The doctor blade will scrape out the excess printing ink from the steel plate while the silicon pad is raising up. The pad can do again to pick up the ink clot for another printing.