Since most of the conductive plastics currently used are of composite structure, the conductive plastic resistance film to be studied by the project team is an apt resin plastic filled with conductive graphite. Therefore, only the main factors affecting the composite conductive plastics and conductive properties are described here. The influence of different types of fillers on the volume resistivity of polycarbonate is shown in Figure 1. It can be seen from the figure that with the increase of filler content, the volume resistivity of the material decreases and the conductivity increases. For different types of conductive fillers, when the content reaches a certain critical value, the volume resistivity of the material slows down. Therefore, there is an upper limit for conductive fillers, not the more the better.
The manufacturing process of conductive plastic displacement sensor includes the manufacturing process of sensitive resistance, brush assembly, shell and other components and the overall detection process of the sensor. Manufacturing process parameters have a great impact on the performance of the sensor. Therefore, choosing a reasonable process is one of the key factors to ensure the quality of the sensor. The sensitive resistance of the sensor is the core of its structure. At present, there are two main manufacturing processes: spraying method and printing method. Spraying method is mainly used in China and printing method is mainly used abroad. The former has high requirements for later engraving, low qualified rate of finished products, and has a certain impact on the environment. It is suitable for manual production and low cost; The latter can achieve high initial resistance accuracy, easy later repair and engraving and high degree of automation, but it needs large equipment investment and is suitable for mass production. The manufacturing process of other parts is not special. Like most precision machining, it only requires high machining accuracy and high electrical insulation performance. As for the overall detection process, the corresponding detection process procedures are mainly determined according to the different requirements for the use performance of the sensor, so as to ensure the reliability and consistency of the quality of the sensor.

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