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Surface treatment method of screw fastener

2021-03-23

Fasteners generally need to undergo surface treatment. There are many types of surface treatments for standard parts. Commonly used are electroplating, oxidation, phosphating, and non-electrolytic zinc flake coating treatments. However, electroplated fasteners occupies a large proportion in the actual use of fasteners. Especially in industries and fields such as automobiles, tractors, home appliances, instrumentation, aerospace, communications, etc., it is more widely used. However, for threaded screws, not only is it required to have a certain degree of anti-corrosion ability in use, but also the interchangeability of threads must be guaranteed, which can also be referred to as screwability here. In order to simultaneously meet the dual use performance of "anti-corrosion" and "interchangeability" required by threaded fasteners in use, it is very necessary to formulate special plating standards.
Three points for attention in the pretreatment process of non-standard screw spraying
One: What is spraying. Spraying is a coating method in which spray guns or disc atomizers are used to disperse into uniform and fine droplets by means of pressure or centrifugal force and apply to the surface of the object to be coated.
Two: Hardware spraying process selection. Metal spraying can be divided into air spraying, airless spraying, electrostatic spraying and various derived methods of the above basic spraying forms, such as large flow and low pressure atomization spraying, thermal spraying, automatic spraying, multi-group spraying, etc. The spraying treatment method should be determined according to the use of different materials.
Three: Conventional hardware non-standard screw spray pretreatment. Degreasing and degreasing → water washing → pickling and rust removal → water washing → neutralization → water washing → surface conditioning → phosphating → water washing → drying → painting / electrostatic powder spraying (normal conditions for degreasing and oil removal, pickling and rust removal process The process must be greater than 25 minutes).
1: When there is no rusty workpiece, the processing flow is as follows. Pre-degreasing→degreasing→hot water washing→cold water washing→cold water washing→pre-table adjustment→table adjustment→phosphating→cold water washing→pure water washing (1)→pure water washing (2).
2: When there is a rusty workpiece, the processing flow is as follows. Pre-degreasing → degreasing → hot water washing → cold water washing → pickling → cold water washing → meter adjustment → phosphating → cold water washing → pure water washing (1) → pure water washing (2)
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