Common factors affecting hot-dip galvanized screws There are several common factors affecting hot-dip galvanized bolts: (1) Pre-treatment is not complete. There is an oxide film on the surface of the workpiece, which affects the normal deposition of zinc. (2) Poor electrical conductivity. The current is consumed on the wire and the current distributed to the surface of the workpiece is too small. (3) The workpiece has a high carbon content. High carbon steel, cast iron parts, etc. will reduce the precipitation potential of hydrogen, accelerate hydrogen evolution on the surface of the workpiece, and reduce current efficiency. (4) The workpiece is tied too densely. When the galvanizing is partially shielded, the coating is too thin. (5) The bath temperature is low. When the bath temperature is low, the current density of the distribution is correspondingly reduced, and the deposition speed of the plating layer is also inevitably lowered. (6) The sodium hydroxide content in the plating solution is high. When the sodium hydroxide content is high, the current efficiency is correspondingly reduced. (7) The additive content in the plating solution is low. Low levels of additives can affect the dispersing ability, and the coating is partially too thin. (8) The estimated area of ​​the plated part is insufficient, and the current density delivered during plating is too small. (9) The workpiece suspension method is improper, and the distance from the zinc anode is too large, and the position should be adjusted. (10) The workpiece is over-etched. The hydrogen evolution potential is lowered, and hydrogen evolution on the surface of the workpiece accelerates the current efficiency, thereby affecting the deposition rate of zinc. An appropriate amount of corrosion inhibitor should be added to the pickling solution. The local scale is too thick to be removed by mechanical means, and more inspection is carried out during the pickling process. (11) Anode passivation. The effective area is reduced, affecting the normal distribution of current. (12) The sodium hydroxide content is low. If the sodium hydroxide content is low, the current density is not high and the anode is passivated. Analysis of surface treatment process of Gulunte u-bolt