There are usually five stages of hot-melt butt joint, namely heating stage, endothermic stage, switching stage, welding stage and cooling stage.

1. Welding preparation: place the pipe fitting between the moving clamp and the fixed clamp, and the distance between the middle two pipe orifices shall be subject to the milling machine.

2. Power on: turn on the power load switch and power on the heating plate for preheating (usually set at 210 ℃ ± 3 ℃).

3. Calculation of pressure P: P = P1 + P2

(1) P1 is the butt joint pressure
(2) P2 is drag pressure: the moving clamp just starts to move, and the pressure displayed on the pressure gauge is drag force P2.
(3) Calculation of butt pressure P: actual welding pressure P = P1 + P2. Adjust the relief valve so that the pressure gauge pointer points to the calculated p value.

4. Milling

Place the milling machine between the two pipe orifices, start the milling machine, set the operating handle to the forward position, make the dynamic clamping bush move slowly, and the milling starts. When the milling chips are discharged from the two end faces, the dynamic clamping stops, the milling machine turns a few times, the dynamic clamping returns, and the milling stops. Check whether the two pipes are aligned, or loosen the clamping bush for adjustment until they are aligned and enter the welding stage.

The first stage: heating stage: place the heating plate between the two shafts so that the end faces of the two pipes to be welded are pressed on the heating plate so that the end faces are flanged.

The second stage: endothermic stage – the reversing lever is pulled to the backward position to release pressure, calculate the time of endothermic stage, when the time is up, start the motor.

The third stage: take out the heating plate (switching stage) – take out the heating plate. The time is controlled within the time listed in the table.

The fourth stage: welding stage – the reversing rod is pulled to the forward position, and the melting pressure is p = P1 + P2. The time shall be as specified in the table, and the cooling stage shall be started as soon as the time arrives.

The fifth stage: cooling stage – stop the motor and maintain the pressure. At the end of the time, the reversing rod is pulled to the opposite position to release the pressure, and the welding is completed.