① The oil stains, rust spots and oxide layer on the surface of the work piece are cleaned and degreased by the chemical method, and there is no grease, turbid liquid and other dirt, and the surface is completely wetted by water.
② The workpiece after pickling has no visually visible corrosion such as oxides and rust spots, and its surface color is basically uniform.
2. Phosphating treatment process of movable shelves:
① Phosphating treatment is mainly carried out by dipping method.
② Phosphating treatment takes zinc-calcium phosphate dihydrogen phosphate as the main component solution. After preparation and adjustment of the phosphating bath, it is carried out in accordance with the requirements of the process regulations.
③ After phosphating, the workpiece is thoroughly washed with flowing water to improve the cleaning quality of the surface of the workpiece. At the same time, the hot complex acid solution is used for sealing treatment.
④ After phosphating and washing with water, use a dryer to process and dry it before spraying.
⑤ The time between the workpiece after phosphating and the spray time is generally not more than 24 hours.
3. Appearance of dense frame phosphating film:
① The color of the workpiece after phosphating is gray, and the film is densely crystallized, continuous and uniform.
② The film thickness is generally controlled to 5 mm.
③ Phosphating surface inspection, using the inspection solution, observe the drip change from sky blue to light yellow or light red, and do not change color within the specified time. The finished product is put into storage and transferred to the spraying process.
4. Movable shelves electrostatic spray technology:
① Plastic powder is sprayed and cured into film by high frequency and high voltage electrostatic equipment. The curing temperature is controlled at 180°C, and the time is controlled in the range of 10 to 15 minutes.
② Color requirements, consistent color, even and smooth plastic surface, no scratches.
③ Inspection standard:
A. Thickness: 45-50 microns Press magnetic thickness gauge
B. Adhesion: Level 2 According to GB-1720-79
C. Impact resistance: 45-50kg/cm according to GB-1732-79
D. Gloss: ﹥85% according to GB-1734-79
E. Appearance: No obvious flow marks, stain marks, bubbles.
