Factors Affecting Wire Plating Efficiency
Author: Robby
Wire plating utilizes a device for continuous plating processing.
With the growth of demand for various types of wire in various industries, improving the production efficiency of wire galvanizing is a practical problem faced by enterprises.
In the past, the wire galvanizing travel speed of mild steel wire was about 5 to 30m/min, depending on different wire diameters, but in actual operation, it was mostly between 7 and 12m/min. If you increase the speed, the thickness of the coating is difficult to ensure. This is a great constraint on the telephone line copper-clad steel plating technology. Therefore, it is necessary to explore the factors affecting the wire plating processing speed and efficiency, in order to find the right way to improve the wire plating rate.
Equipment factors
Continuous plating device for the wire, the take-up speed of the take-up machine is to control the wire plating line speed of the main institutions. Some take-up machine speed can reach 200m/min or more, if such a high speed plating, with a diameter of 2mm wire calculation, each kilometer weighs about 25kg, it can be plated out 300kg of wire per hour. The general wire continuous plating is a multi-head device, only 10 head calculation, the hourly output of up to 3t. This calculation, the daily output is very substantial.
But China's current operation of the wire continuous plating device almost no unit can achieve such a high yield, and some even one-tenth have not reached.
Plating process has to reach a certain thickness, only with the set protective properties and other physical properties. Among the factors that determine the thickness of plating layer, the main ones are current density and plating time when the current efficiency is certain. Obviously, when the wire high-speed movement, to ensure that there is enough plating time, there must be a sufficient length of the plating tank.
If still 200m/min of high speed plating, to achieve the lower limit of the national standard for the thickness of the plated layer, in the ordinary case at least 2min plating. in this way, the plating tank needs to be 400m long, which is difficult to achieve in the actual production, therefore, only appropriate to slow down the walking speed or according to the site limitations to determine the speed of the walking speed. For example, if you can only use 20m long plating tank, that is to achieve the minimum thickness of the plating layer, the line speed can only be 10m/min. When the requirements of a thicker layer, it can only be appropriate to extend the length of the plating tank, in order to maintain the required output. At present, the length of the domestic wire plating workshop is mostly in the 100m or so, some as long as 200m, because the plating line itself has been 150m long. This not only covers a large area, plating plant room and equipment investment is also very large. Therefore, can not rely on increasing the length of the plating line to meet the requirements of the plating thickness.
Plating process factors
When the closing speed and the length of the plating tank are certain, the only way to increase the thickness of the plating layer is to increase the current density. In fact, the current density of wire plating process is higher than that of conventional plating. Otherwise, it is impossible to implement plating processing on some plating lines with limited length of plating lines. But when some companies try to further increase the current density to shorten the plating time, often do not achieve the desired purpose.
The first is the limitation of the plating process itself. The working current density range of each plating solution is certain and cannot be increased at will. If you want to increase the current density to improve the rate, not only to adjust the process formula, but also involves the modification of equipment. Secondly, a large current density can easily cause anode passivation, and the anode itself is constantly shrinking during the plating process, which increases the current density of the anode even more, making the anode more susceptible to passivation. The only way to overcome the electrochemical resistance is to make the voltage higher. In this way, when the amount of electricity is constant, the current intensity will decrease, and the purpose of improving the plating speed can not be achieved. At the same time, large current density will also make the plating solution temperature rise faster. When the temperature exceeds the process specification, the plating process can not be carried out normally.
In addition, the current efficiency is also an important factor affecting the plating speed. In the high-speed plating process, the impact of current efficiency is greater than that of conventional plating. Therefore, high-speed plating solution is often a simple salt plating solution, and only when necessary to add the appropriate additives. For example, wire galvanizing has been using sulfate galvanizing process. In order to improve the quality of the plating and the appropriate addition of some organic additives. Traditionally, there are gum arabic, gelatin, thiourea and so on. Nowadays, there are professional brightening agents such as “Sulfur Zinc-30”. The current efficiency of sulfate zinc plating is more than 99%, and it is desirable to use it as the mother liquor for high-speed plating.