Thermalshrinkage mainly refers to the volume change of thermoplastic materials (ABS, paraffin, etc.) due to their inherent thermal expansion rate, which is the main reason for shrinkage. The shrinkage caused by thermal shrinkage is: δ L = δ× (L+δ/2 )× δ T < P >, where δ is the linear expansion coefficient of the material,/℃; L is the X/Y dimension of the part, mm; Δt is the temperature difference,℃; Δ is the tolerance of the parts (take the largest compensation according to the machining allowance). Heat shrinkable material, also known as polymer shape memory material, is an intelligent material combining polymer material with radiation processing technology, that is, a functional polymer material made of rubber and plastic materials by mixing, molding, crosslinking, heating, expanding and cooling. Ordinary polymer materials, such as polyethylene and polyvinyl chloride, are usually linear structures. After being transformed into a network structure by radiation from radioactive sources such as electron accelerators, these materials will have a unique "memory effect", and the expanded and cooled materials can shrink back to their original shapes after being heated.

The memory property of heat shrinkable materials can be used to make heat shrinkable pipes, films and profiles. Its main feature is that it can be wrapped on the outer surface of objects by heating and shrinking, and it can play the roles of insulation, moisture-proof, sealing, protection and connection, and the radial shrinkage rate of shrinkage materials can reach 51% ~ 81%. With these special excellent properties, heat shrinkable materials are widely used in the fields of sealing and anticorrosion of chemical and petroleum pipelines, joint insulation protection of household appliances, control cables, national defense communications, power cables, shielding connection of electrical components, insulation sealing and so on. With the rapid expansion of the heat shrinkable material market, a cluster of power accessories manufacturers has been formed around it, and then some of its personnel and technology have gone south to Guangdong, Zhejiang and so on. Due to the concept, mechanism, surrounding market demand and investment, at present, more than 51% of electrical heat shrinkable tube enterprises are concentrated in Guangdong, among which Changyuan, Woer, Kaiheng and Hongshang all belong to Chu Qiao.