How To Make Heat Shrinkable Intermediate Joint

How to make heat-shrinkable intermediate joint and the production process of heat-shrinkable tube.

In today’s society, heat shrinkable casing is widely used in electronics, power, cable and other fields as well as daily life plays an important role in social development. 

Heat shrinkable casing is an alloy of radiation crosslinking polyolefin and its polymer, which produces shape memory effect after high-energy ray radiation, so as to realize the coating of various wires and cable joints and the purpose of insulation protection. 

So what are the manufacturing processes of heat shrinkable casing? 

It is mainly divided into four parts: the first mixing granulation, the second extrusion molding, the third radiation crosslinking, the fourth expansion shaping, packaging.

The production process of heat shrinkable sleeve has the following three points:

There is a chemical formula.

Molding technology (extrusion molding technology, injection molding technology).

Transmission control technology, tension control technology, expansion production technology and other production technology that requires accurate calculation.

The manufacturing process of heat shrinkable sleeve has the following four points:

Expansion to finalize the design


Heat the plastic pipe after radiation crosslinking to the high elastic state, and then use the expander to expand to get the heat shrinkable sleeve.

The process parameters of expansion finalize the design are: temperature 120~150℃, input speed 8~10Hz, pull out speed 8~10Hz, vacuum degree -0.06MPa.

Extrusion molding


Extrusion molding is by extruder, cooling water tank, tractor, tension machine and winding machine to complete. 

Its technological parameters are: extrusion speed of 20~50r/min, traction speed of 30~50 Hz, extruder temperature of 90~130℃.

Mixing granulation


Weigh all raw materials according to the formula and use a high-speed blender to stir them evenly, with a stirring volume of 110kg and a stirring time of 8-12min. 

Mixing and granulating are accomplished by pelleting machine, cooling water tank, blow drying machine and granulating machine. 

The mixing and granulation process parameters are as follows: the main engine speed is 1 000~1 400r/min, the feeder speed is 50~80r/min, the body temperature is 110~160℃, the head temperature is 190~240℃.

Radiation crosslinking


The function of the electron accelerator is to generate rays and irradiate the plastic pipe so as to produce crosslinking.

The function of the beam transmission device is to continuously send the plastic pipe into and out of the electron accelerator.

After the winding times are determined,  the desired radiation dose can be obtained by controlling the speed of the electron accelerator beam and the transmission device.  

These production processes can greatly reduce the investment cost of heat shrinkable casing, reduce energy consumption and enterprise production costs, improve production efficiency and product quality, and produce products with relatively high mechanical strength and long service life, corrosion resistance, aging resistance, environmental pressure and other advantages.