Heater band for hot runner injection molding systems

A heater band comprising:

• a cylindrical sleeve defining a longitudinal centerline axis;
• a first wire heating element having a first contact terminal, a second contact terminal, and an intermediate portion therebetween, the first contact terminal and the second contact terminal being separated from each other by a first fixed distance and protruding from an axial end-portion of the cylindrical sleeve, the intermediate portion of the first wire heating element being disposed in a first serpentine pattern within an interior portion of the cylindrical sleeve such that the intermediate portion of the first wire heating element repeatedly doubles back on itself about the circumference of the cylindrical sleeve and includes spaced apart vertical portions that are parallel to the longitudinal centerline axis of the cylindrical sleeve, wherein adjacent ones of the spaced apart vertical portions of the first wire heating element are connected to each other via an upwardly curved portion or a downwardly curved portion spanning 180 degrees;
• and
• a second wire heating element having a first contact terminal, a second contact terminal, and an intermediate portion therebetween, the first contact terminal and the second contact terminal being separated from each other by a second fixed distance and protruding from the axial end-portion of the cylindrical sleeve, the intermediate portion of the second wire heating element being disposed in a second serpentine pattern within the interior portion of the cylindrical sleeve such that the intermediate portion of the second wire heating element repeatedly doubles back on itself about the circumference of the cylindrical sleeve and includes spaced apart vertical portions that are parallel to the longitudinal centerline axis of the cylindrical sleeve, wherein adjacent ones of the spaced apart vertical portions of the second wire heating element each other via an upwardly curved portion or a downwardly curved portion spanning 180 degrees;
• wherein the intermediate portion of the first wire heating element is adjacent to and axially offset from the intermediate portion of the second wire heating element, and wherein the first fixed distance being equal to the second fixed distance such that the first and second contact terminals of the first wire heating element and the first and second contact terminals of the second wire heating element can be alternatively connected to an electrical power supply to extend the operational life of the heater band.