(1) There is no powder on the workpiece or the coating is extremely thin
Cause analysis: there is oil on the workpiece, the preheating temperature is too low or the time is too short; the workpiece has cooled when it enters the fluidized bed after preheating; the voltage of the electrostatic method is too low.
Prevention and control methods: rework and degrease again; construction according to the specified temperature and time; construction according to the process, small parts that are easy to cool should be accelerated into the fluidized bed; increase the voltage to the specified value.
(2) The coating film is sometimes too thick, sometimes too thin
Reason analysis: the preheating temperature is not stable, more powder is deposited when the preheating temperature is high, and less powder is deposited when the temperature is low, or the length of preheating time is not fixed; the fluidization of the workpiece is also unstable, and the fluidization time Longer coating film will be thicker, short fluidization time will be thinner.
Prevention and control methods: maintain the preheating temperature and time; maintain a stable fluidization time.
(3) The coating film is brittle and has low adhesion
Reason analysis: the curing temperature is low or the time is short and the plasticization is not complete; the curing temperature is too high.
Prevention and control methods: strictly follow the construction process; control the cooling time of the workpiece in the air; surface surface according to the specified temperature and time, and often check the accuracy of the temperature control device.
(4) The coating film has sagging, and local block sags appear
Reason analysis: the preheating temperature of the workpiece is high, too much powder is applied during fluidization; the plasticizing temperature is too high.
Prevention and control methods: Determine the preheating temperature of the workpiece according to the different melting points of the powder, and do not increase the temperature casually; strictly follow the construction process; if the sagging is serious, it should be scraped off or the coating should be removed by chemical plastic removal and recoated.
