Printing machine rubber roller basic knowledge
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The ink roller on the press is mainly used to transfer ink. In order to distribute the ink rapidly and evenly between the ink rollers, the printing machine is usually arranged in an alternating manner between a soft ink roller and a hard ink roller to make good contact between adjacent ink rollers.
Soft ink rollers (commonly known as rubber rollers) are generally made of high-grade polymers such as vulcanized natural rubber, synthetic rubber, gelatin, and polyurethane; rigid ink rollers (commonly referred to as metal rollers), generally iron Made of copper or other metal materials. The rubber roller and the metal roller themselves have good lipophilicity, so that the ink is well wetted and adhered on the surface, which is a prerequisite for ensuring the transfer of ink between the ink rollers.
Rubber roller manufacturing process
-Main raw materials: high molecular polymers, vulcanizing agents, plasticizers, fillers, accelerators
-Main process and function: mixing - filtration - curing treatment - grinding - polishing
1. Mixing: Control the content of each component, heat drying temperature, etc., to stabilize the hardness and composition.
2. Filtration: Make the colloid even and free of impurities. This is especially important for high-speed printing presses: uniform force during high-speed operation, uniform transmission of energy due to various factors, even when expanding or contracting, so that uniformity can be maintained, so that only relying on adjustment can reduce or avoid adverse effects.
3. Curing: Stabilize the speed-increasing agent by heating, pressurizing and vulcanizing to minimize the shrinkage of the rubber when subjected to external force. The soft and ductile compound is made into a solid material with a certain degree of softness, which is more suitable for ink transfer and transfer.
4. Grinding and polishing: The key to determining the dimensional accuracy and surface area of the rubber roller, especially the arc treatment of the alcohol water roller. The rubber surface looks smooth, but under a high magnification magnifier, there are many small bumps and depressions. These raised and recessed portions increase the surface area of the rubber roller, making it superior in ink transfer and transfer properties.
This process requires a constant temperature: the temperature is too high, the surface is easily charred, and peeling occurs when printing is short-time. The temperature is too low, and the part is easily embrittled, resulting in a decrease in ink transfer performance.
Rubber roller performance requirements
- Inclusive - affinity for water and ink
- Elasticity - Is it possible to express pressure correctly; good elastic pressure is obvious
- Indentation reflection - the basis for correct adjustment of printing pressure
- Vibration absorption - Prevents up and down, resonance (at high speed)
- Abrasion resistance - maintains high surface area, anti-glaze ability and maintains inclusiveness
- Energy transfer performance - to ensure that it does not accumulate energy, does not reflect energy
- Corrosion resistance - good chemical resistance, helping to extend life
- Conductivity - antistatic, non-adsorbing ink and paper
- Heat transfer - Extends its life and reduces the time to adjust the pressure
- High temperature resistance - extended rubber roller life (especially for high speed machines)
Rubber roller hardness
The hardness of the rubber roller is an important performance of the performance of the rubber roller. The specific performance is as follows:
- Soft - good inclusiveness, high elasticity, strong pressure resistance, good vibration absorption, good indentation reflection, large adjustment range of pressure
- Has a certain hardness - not easy to be corroded and worn, strong resistance to high temperature, rapid pressure performance, so the hardness of the rubber roller needs to be moderate: too soft, poor corrosion resistance, easy to gather energy; too hard, the ability of ink transfer is reduced, the vibration absorption is poor, easy Gradually destroy the precision design of the printing press. Therefore, it is necessary to select the correct gel type and hardness according to the appropriate printing pressure and other printing suitability.
Attachment: Indentation performance of the rubber roller (indentation width - rubber roller pressure)
- Increase the indentation width by 50% relative to the need to increase the pressure of the roller by 250%
- Increase the indentation width by 100% compared to the need to increase the roller pressure by 750%
- Try to lighten the pressure of the rubber roller