uPVC Window Door Making Manual

Part 5 Profile Welding

This is uPVC window door making manual part 5. This part mainly introduces profile welding. This part also very imports to the whole uPVC window door making procedure.

1. Which kind of machine do we use?

Among all the uPVC window door machine, there have several uPVC window and door corner welding machines for us to use.

Below are the machines:

We should choose the machine according to different process program.

If we want to make a different angle window, we need variable angle single head welding machine.

If we only make the regular window frame, we could choose a double head welding machinethree head welding machine, and four head welding machine. These machines also could make the mullion welding also. No need to buy any other “mullion only” machine.

If we need more high efficiency we could use CNC four point welding machine.

For the uPVC window colors, we could use normal welding machine or seamless welding machine.

uPVC window welding machine seamless welding

2. Welding sequence

For some simple uPVC windows and doors, we could know clearly the welding sequence, or no need to draw.

But in the uPVC window making process, for some complex windows, before welding, we should decide the welding sequence according to the window design.

If the window does not has division, we could use four corner welding machines. Welding the frame and sash one time. If the mullion has many divisions, we should weld the mullion then frame. Please check below.

Welding Sequence

3. Welding parameter

These parameters affect the window door quality. Especially affect the welding corner intensity.

So, we should formulate and control the welding parameter strictly.

The main welding parameters as follows:

Welding temperature:240℃-270℃
Clamping pressure:0.4MPa – 0.6MPa
Welding pressure:0.3MPa – 0.4MPa
Joint pressure:0.4MPa – 0.5MPa
Welding time:20s – 30s
Joint time:25s – 35s

Above parameters are very basic. Different machine, different condition and different profile, the parameter should change accordingly.

We should follow the welding machine instruction. Or find the best welding parameter through the test by us.

We could adjust the relative parameters according to the below steps:

1) Adjust the welding temperature within 240℃-270℃. Each time change 1-2℃. We could decide the temperature through the welding surface. Normally the welding surface is light yellow.

2) After decided the welding temperature, then adjust the welding time and joint time accordingly.

3) Adjust the clamping pressure within 0.4MPa – 0.6MPa, and ensure the profile not has deformation and displacement. Welding pressure adjusting keeps the welding end surface smooth.

Temperature, time and pressure are the very important parameters. In the production, we should according different situation to do some test and adjustment. Make these three parameters best match to keep the welding quality.

4. Preparing before welding

Before welding, we should do some preparations:

1) Check the welding machine’s power, pressure. And every parameter within the right work scope. Preheat 20-30minutes after power on.

2) Keep the environment temperature above 18℃. The upvc profiles in the same condition at least 24h. This way will lower the temperature gradient between profile and heating temperature. It will help increase the welding intensity.

3) According different profile choose the right welding time, temperature and pressure.

4) Mark the relative welding profile and put in the assigned position. Please notice the position of installation holes, hinge, handle and drainage holes to avoid the wrong welding.

5) Please not make the gasket, wool strip and profile film welded.

5. Welding Notice

In the upvc window frame welding, we should notice some items as below:

  • During welding, we must ensure the visible welding surface and the welding plate orthogonal. Tolerance ±0.5°.
  • Keep the welding surface clean. This can avoid the dark line in the welding corner.
  • Make sure the angle within 45°±0.5° between the guide board and the positioning plate.
  • After fame and sash welding, the size must fulfill the dimension requirement.
  • In bulk production, we must check the first finished product carefully. And take some samples to check.
  • In small quantity and single piece production, we should check all the finished products.

uPVC windows tolerance

Size300~900mm901~1500mm1501~2000mm>2000mm
tolerance≤±2.0mm≤±2.5mm≤±3.0mm≤±3.5mm
Size≤2000mm>2000mm
tolerance≤±2.0mm≤±3.5mm
  • The diagonal line of the window frame and sash should less than 3.0mm.
  • Mullion welding must ensure the two welding parts’ angle within 90°±0.5°.
  • After welding, same profile welding parts surface flatness ≤0.5mm. different profile welding parts surface flatness ≤0.8mm
  • After welding please ensure the main profile welding corner intensity and do some test regularly.

6. welding mould for profile

We should make the matched welding mould for profile according different uPVC profiles.

The welding mould normally lowers 0.5mm-1.0mm than the profiles.

Because the after-cutting profile angle is 45 degrees with a sharp corner. If not use welding mould, the sharp corner will defamation under the pressure.

The overlap bottom will bigger. The welding surface stress will be maldistribution per unit area. And this will affect the welding quality. Below is the picture for your reference.

Corner Welding Modeling

7. some attention for welding machines

1) Please check the welding machine regularly. Checking whether the positioning crew loose or not. This will ensure the welding parameter has the right positioning.

2) The welding Teflon paper must on the heating plate tightly.

3) Keep the Teflon paper clean. Every 10 times clean once. And after 1000 times welding, we should change it.

4) Keep the machine away from the windy place. Because this will affect the welding plate temperature.

5) After each time welding, we should interval some time let the temperature recover to the set point.

6) Not change the welding machine operator. This will be helpful for the welding quality.

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