Causes and Prevention methods of mildew spots in plastic plating-plastic plating parts

Causes and Prevention methods of mildew spots in plastic plating-plastic plating parts.
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In summer, some plastic plating factories in the south often find some small white spots on the plated parts, which are difficult to wipe off, affecting the appearance of the products and even leading to scrap. Although the electroplating process conditions are normal, it is difficult to avoid, and even appear in large quantities. This is a special electroplating problem, which is called moldy spot of electroplated parts. In the following, combined with the technological process, on the basis of discussing and analyzing its causes, the methods to prevent the occurrence of such problems in production are introduced.
technological process.
Hanging with "deoiling", "hydrophilic", "coarsening", "water washing", neutralizing "water washing" pre-immersion "catalysis", "water washing", "ungluing", "washing", "electroless nickel plating", "water washing", "flash copper", water washing, acid activation, "acid copper plating", water washing, acid activation, multi-layer nickel plating, acid washing, acid activation, bright chromium plating, water washing, drying "lower hanging equipment" inspection "packaging" into storage.
Analysis and discussion.
The mildew spots on plastic electroplating parts are formed by the attachment of mildew rot microorganisms. the source and survival conditions of mold rot microorganisms and the stage and place effectively attached to the plating parts are the key to discuss the causes and prevention methods of mildew spots.
The high temperature and humidity in the south in summer is the time for mildew and rot microorganisms. The raw materials, water, personnel and dust that enter the electroplating workshop may be brought into mildew rot microorganisms and their spores, as long as they have enough moisture (humidity). Even when other nutrients such as nitrogen, carbon, minerals and vitamins are rare, they can grow. Even if there are no external nutrients, as long as humidity, temperature, PH value and other conditions are appropriate, mold spores can develop to a certain extent depending on their own stored nutrients. It can be seen from the above technological process that electroless nickel plating bath, electroless nickel plating water washing tank, bright chromium plating water washing tank, underdried products, inspection and packaging workers' gloves, packaging and storage supplies are all important places and stages for effective attachment of mildew rot microorganisms, once moldy rot microorganisms or their spores exist and survive in these places, it will lead to mold spots on electroplated parts.
Prevention method.
According to the above discussion, the key to prevent the mildew spot of plastic plating parts is to control the source of mildew rot microorganisms, minimize the chance of contact with the products, and carry out sterilization treatment in the stage and place where they are attached effectively. try to eliminate the survival conditions of moldy microorganisms. The following specific measures can be taken in actual production:
(1) pay attention to ventilation, dust removal and sterilization in workshops and warehouses, so as to reduce or eliminate microbial pollution sources of mold rot as far as possible.
(2) keep raw materials clean and hygienic. For example, the sodium citrate solution for electroless nickel plating should be heated to about 80 ℃ before adding.
(3) the water used should be sterilized. The ion exchange resin in the water purification equipment should be regularly sterilized and cleaned with formaldehyde or ethanol; after electroless nickel plating, an appropriate amount of formaldehyde should be added to the washing tank every day, and ethanol should be used in each shift; the water used for washing after bright chromium plating must be irradiated and sterilized by ultraviolet lamp.
(4) the drying temperature and time of electroplated parts must be enough, and it is absolutely forbidden to have water on the workpiece after drying.
(5) White gauze gloves used by inspection and packaging workers must be dry and clean, and plastic film gloves should be worn inside.
(6) the packaging supplies should be clean and dry, and the desiccant and anti-mildew agent can be put into the packing box.
(7) the electroplated parts should not be placed in the workshop with high temperature and humidity for too long, and should be quickly moved to the warehouse after packing.