Application of PLC in the Electroplating Automation Manufacture
Abstract
The waste liquid, gas and residue produced in the electroplating production will do harm to the environment and the human body, so it is essential to realize automatic electroplating manufacture. The technological process of automatic electroplating manufacture and the overall arrangement of plating tanks are discussed in this paper.
MITSUBISHI FX PLC is used to control the automatic electroplating reciprocate production line. PLC I/O terminals configuration, control flowchart and corresponding ladder program is discussed at the same time. Thus could improve working condition and raise working efficiency.
1. Introduction
Electroplating is widely used in manufacture, electronics and national defense industry. The surface property of solid materials could be changed through electroplating. In mechanical products, the part number that needs to be electroplated is amount to 80~90%. With the rapid social development, the part quantity of ferrous metal, nonferrous metal and other nonmetals will be increased.
This will put forward arduous task to electroplating industry. But the waste gas, waste liquid and residue does harm to the environment and human beings. To realize automatic electroplating is imperative.
2. Technological Process
The total length of this electroplating production line is about 20 meters. There are 17 plating tanks in this production line such as copper plating tanks, rinse tanks and so on. The production mode adopts reciprocate mode. The motion sequence is shown in Fig.1 [1]. In Fig.1, the vertical real line, the vertical broken line and the horizontal real line represents right hook, left hook and traveling crane respectively. There are 31 technological steps. The 31steps could be merged into one circulation.
 |
| Fig. 1. Electroplating process flow diagram |
According to different technological demands, the electroplating time could be calculated by Eq.
Where:
- t-electroplating time, min;
- d-coat mean thickness, μm;
- K-electrochemical equivalent of the metal to be plated, g/(A.h);
- Dk-cathode current intensity, A/dm^2;
- ηk-cathode current efficiency, %;
- ρ-density of the metal to be plated, g/cm^3;
The traveling crane motion speed should be controlled between 12 and 20m/min. The up and down speed of the hook should be controlled between 8m/min and 12m/min. With calculation, the copper-plating time of some part is about an hour. To make full use of this time, 8 copper-plating tanks are set. In every copper-plating tank there are 2 places on the left or right side respectively to put the parts.
During this hour, the parts to be plated are put successively in the 8 tanks by the right hook and the plated parts are fetched by the left hook. This is called a cycle. There are 8 circulations in a cycle. So in the next cycle, it must be that the left hook put the parts to be plated, and the right hook fetch the plated parts. In this cycle, there are also 8 circulations. There are 31 technological steps in every circulation. The cycle that right hook put the parts to be plated and the left hook fetch the plated parts is called single cycle. The conversely cycle is called double cycle.
References:
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Electrical Automation 28(2), 64–67 (2006) (in Chinese)
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