The present disclosure relates to a band heater assembly (100). The band heater assembly (100) includes a thermally insulating band (105) that encases a screw barrel (110). The band (105) is defined by a plurality of channel blocks (105a,105b, 105c,..., 105n) interlocked with each other by means of a securing means. Each block (105a,105b,..., 105n) is defined by an interior surface that rests against the outer surface of the barrel (110), and an operative exterior surface. The assembly (100) further includes heating elements (115) embedded in the band (105). Each heating element (115) is held at a predetermined gap from the surface of the barrel (110) by the band (105), thereby resulting in uniform distribution of heat. Hence, smaller number of heating elements (115) is required for achieving the desired heat distribution.