Injector for injection-moulding of plastic materials

An injector for injection-moulding of plastic materials, comprising:

• a generally cylindrical body with a proximal end and a distal end;
• a central channel for passage of the plastic material to be injected towards said proximal end;
• electrical-heater means generally spirally wound around the outer surface of said body;
• control-thermocouple means operatively associated to said electrical-heater means, wherein said electrical-heater means include two independent resistors positioned on said body substantially at the same radial distance from said central channel;
• and
• wherein said injector comprises at least one first pair and one second pair of said resistors, the first pair of resistors extending from said distal end along a first axial portion of the body of the injector and the second pair of resistors extending from said proximal end along a second axial portion of the body of the injector, each pair of said resistors being operatively independent of the other pair.