With the term welding, in thermoplastic materials, we mean an indissoluble cementation obtained by specific temperatures and pressures, with or without the use of filler materials.
The welding occurs when the material, in the slot or on the surface, is brought to a temperature of merge.
The thread-like molecules of the two pressed parts come together and intertwine with each other, producing homogeneous union. This also takes the name of fusion.
Only the materials of the same substance plastics can be welded together (for example PVDF with PVDF, PP with PP) and, accordingly, only those of the same or similar molecular weight and density.
For this reason, the non-rigid polyethylene is welded with the soft one, while the color difference does not affect the consistency of the weld.
Let’s see what you need to know for the infrared welding.
1. Welding Method
In the process of infrared welding the areas of the components (e.g. pipe fittings, valves) are heated up to the desired temperature by the mechanical pressure without the aid of additional materials.
The infrared joints of this type can only be obtained with machines for infrared welding.
The resulting fusion is homogeneous and shows the following characteristics:
– the heat generated in the absence of contact with the heating element eliminates the risk of contamination and not homogeneity;
– burrs produced (strings) are minor thanks to auto-equalization (no longer exists the standard equalization process):
-the fusion process ensures its reproducibility;
– it’s reduced to a minimum the possibility of the formation of stress points.
2. General Requirements
The basic rule is that only materials of the same type can be welded together.
The best results are obtained only with materials whose melt index is contained in the range between 0.4 and 0.8 g / 10 min.
The components to be welded must have the same thickness of fusion’s notification area. The maximum degree of acceptance is the +/- 10%.
The merger IR can only be operated by qualified personnel.
3. Tools Required
The infrared fusion necessarily require the use of a special emitting welding machine of infrared rays in addition to the normal tools used for construction in plastic materials (pipe cutter,
4. General Conditions
Protect the fusion area to adverse weather conditions like rain, snow or wind.
The allowable temperature for the fusion must be contained in a range between 5 ° C and 30 ° C. Outside of this range it’s necessary to apply specific measures to ensure that in the welding area the aforementioned conditions are maintained.
It must also be ensured that the components to be joined have a temperature compressed in the limits.
5. Preparation of Components
In principle, the infrared (IR) fusion requires no special preparation, but you have to make sure the components to be welded are clean of impurities.