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About Heat Shrinkable Tube and Precautions for Its Selection

1. About the heat shrinkable tube


The heat shrinkable tube is a tube specially made of polyolefin material which will shrink when heated. The surface layer is made of high-quality soft chemically cross-linked polyolefin raw material and the inner layer of hot sol composite production and processing. The surface material has the corrosion resistance on insulating layer, wear resistance and other characteristics, and the inner layer has low melting point, moisture-proof sealing and high adhesion and other advantages.


The heat shrinkable tube has the functions of high temperature shrinkage, soft flame retardancy, and anti-corrosion of the insulating layer. As the temperature changes from low to high, the fiber material will experience the state of laminated glass—high elastic state. The properties of fiber material in the laminated glass state are close to those of plastic, and the properties of it in the high elastic state are close to those of vulcanized rubber. The commonly used raw materials of heat shrinkable tubes are in the state of laminated glass at room temperature, and become highly elastic after heating.


During manufacture, the heat shrinkable tube is heated to a high elastic state, the load is released to make it expand, and it is rapidly cooled while maintaining the expanded state, so that it enters the state of laminated glass, and this state is fixed. As soon as it is heated during application, it becomes highly elastic, but when the load is gone, it shrinks.


2. How to choose the heat shrinkable tube?


(1) The heat shrinkable tube and the heating equipment do not need to be too close together. Be sure to pay attention to the distance between the fire and the heat shrinkable tube, that is, move 4 to 5cm evenly. When heating up, there is no need to exceed the high temperature resistance limit of the heat shrinkable tube. For the heat shrinkable tube, if the temperature exceeds the high temperature resistance limit, it will make people's goods "melt" and return to the original state.


(2) Select a suitable special heating tool. In the case of heating and baking, the outer flame of the flame and the surface of the heat shrinkable tube form an included angle of 45°. Be sure to pay attention to the reciprocating movement to ensure the heat shrinkable tube is heated as a whole. Gradually move it from one end to the other end, and the heating should be uniform to prevent air bubbles, so as to ensure the appearance design of the heat shrinkable tube after being folded. And unfold and adjust it after cooling.


(3) The heat shrinkable tube has different heat shrinkage multiples. The specification and model of the heat shrinkable tube generally refers to the product of the larger nominal diameter allowed by the waterproof casing and the product of the shrinkage multiple. For example, if the shrinkage ratio of the heat shrinkable tube is 2:1, in other words, the heat shrinkable tube that is twice the diameter of the product itself can be used for application. For example, if the diameter of the covered object is 20mm, people can choose a heat shrinkable tube with a diameter of 40mm.


(4) For cables, you can select the heat shrinkable tubes with the same diameter of the product; the safety protection of copper bars in power plants and electric control boxes should use copper-bar heat shrinkable tubes; if there are regulations on sealing, use moisture-proof heat shrinkable tubes.