The powder coating is widely used in die casting aluminum parts. Though the surface treatment process is mature, and the effect is good, defects still inevitably arise. Here are the defects with solutions.
1.There will be color difference when powder coating.
a.Ensure that the coating thickness of the aluminum alloy die-casting part is uniform;
b. The temperature distribution of the curing furnace is uniform;
c. It should be classified according to the material, thickness, shape and size of aluminum alloy die-casting parts, and then set different baking time for baking and curing, which may reduce the color difference of the coating film;
d. When replacing the paint, clean the parts and try to stagger the materials with different color difference.
e. Improve the quality of the powder to ensure that the L, a, b of the powder are not much different.
2.Aluminum alloy die-casting parts have yellowing, loss of light, etc.
a.Use high quality powder coating;
b. Wipe clean after pre-treatment, clean the debris before painting;
c. Select the appropriate curing temperature and time, the curing furnace increases the hot air circulation to ensure the proper distance between the workpiece and the heat source;
d. Thoroughly clean the powder supply barrel, recovery system, powder feeding tube, spray gun, spray chamber and other devices when changing powder.
3.Sprayed aluminum alloy die casting parts have bubbles, shrinkage holes, pinhole defects.
a. Control the concentration of the degreasing tank, reduce the amount of oil in the profile and enhance the washing effect;
b. increase the oil-water separator to achieve dry compressed air;
c. Select high-quality powder coating or improve powder storage and transportation conditions, increase dehumidifier to ensure timely use of recycled powder;
d. Clean the hanging chain in time to ensure that no oil is dropped;
e. Thoroughly clean the dusting system when changing powder;
f. Spray at a suitable distance (preferably 150-300 mm).