E is the heat energy,
I is the current,
R is the
electrical resistance of the wire and
t is the time that the current is
The two parts are joined under pressure and the plastic that surrounds the
wire is softened or melted by the heat. The plastic solidifies when the
electric current is switched off and the bond is formed.
The process is suitable for very large parts due to the minimal equipment
requirements, but has the disadvantage that a sacrificial heating wire is
required, which remains in place after welding, adding to the process costs.
It is a reversible process, which permits repair of misaligned joints and
defective components, and also improves recyclability. The presence of the
wire in the weld may have a negative influence on the weld strength.