Identification of Corrosion Causes of Offset Presses

offset printing machine is a lithographic printing machine. Its working principle is based on the principle of indirect printing. The graphics and text on the printing plate are continuously transferred between the blanket and the printing medium to achieve a certain contact pressure, thereby transferring the graphics and text to the required printing medium.
offset printing machine is suitable for some prints with high printing quality requirements, rich colors, high printing accuracy and small layout size. When printing, due to the high elasticity of the blanket, it can better adapt to printing materials of different sizes and perform well in printing accuracy.
In the case of identification of corrosion causes of offset printing machines, Zhongke Testing can provide corrosion cause identification services of offset printing machines.

1. Causes of corrosion from the outside in
In any electroplating solution, regardless of the pH value, certain hydrogen ions will be produced due to the electrolysis of water molecules. When metal precipitates at the cathode, it is usually accompanied by hydrogen precipitation.
chrome plating solution is one of the most serious hydrogen evolution solutions, and hydrogen evolution has a great impact on the coating. Hydrogen adsorbed in the pores of the base metal or intermediate coating will expand as the temperature of the surrounding medium increases, causing small bumps in the coating. When hydrogen sits on the surface of the plate cylinder, it prevents metal ions from depositing in these parts, causing pitting in the coating, a potential hazard for "pitting" of the chromium layer.
2. The cause of corrosion is from the inside out.
generally has obvious small bumps, which are mainly caused by improper surface treatment before chrome plating and poor combination of the chromium layer and the copper layer. In addition, some ingredients in some inks are corrosive to the chromium plating layer on the surface of the printing plate. They corrode the copper under the chromium layer through blisters on the chrome plated surface, causing the copper and chromium layers to peel off.

GB/T 17861-1999 Office machinery Offset printing machine Installation characteristics of printing plate
JB/T 14058-2022 Curved letterpress offset printing machine
JB/T 14057-2022 Flat letterpress offset printing machine
JB/T 12152-2015 Office machinery Small offset printing press Reliability requirements and test methods
JB/T 8267-2015 Office machinery Small offset printing machine
JB/T 5433-1991 Metal plate platform offset printing machine

According to the information provided by the client, the company installed an offset printing press purchased from a printing equipment company in the workshop in June of
In view of this, the client requested the user to add dehumidification equipment in the workshop to maintain a constant temperature and humidity in the workshop environment. However, it was still unable to control the rapid corrosion and rust of the equipment, and this phenomenon continued to worsen.
Therefore, the equipment user suspected that the equipment had quality problems, failed to conduct a qualified acceptance of the equipment sold by the client, and applied for product quality analysis of its equipment.
was entrusted by the client to conduct identification and analysis of the causes of rapid corrosion of the metal parts of the offset printing machine involved.
identification analysis results: The
expert group analyzed the relevant information, on-site investigation and test results of the "offset printing machine" involved in the case. After discussion, the opinions are as follows: The external materials used by the offset printing machine contain chlorine and form HCl gas in the environment around the equipment. The working environment of the equipment is too humid, causing rapid corrosion of metal parts in the hydrochloric acid environment or the electrochemical action of chlorine ions.
also recommends:
1. Identify and prohibit the use of materials with high chloride ion content;
2. Strictly control the working environment humidity of the equipment to meet the environmental use conditions of the equipment;
3. The equipment workshop should appropriately adopt external air circulation methods to ensure a certain number of air changes;
04. Thoroughly derust and clean the rusted areas of the equipment to remove chlorine ions attached to their surfaces.
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