According to the mutual relation between the flow direction of the material in the extruder and the head, it can be divided into five types: straight-through head, right-angle head, lateral head, sieving head and double-layer heterotype head.

Straight through machine head also known as straight pipe machine head. The flow direction of material in the machine head and extruder is one kind of universal machine head. The disadvantage is that it is difficult to heat the core mould when producing pipe with large outer diameter. The mechanism head of this structure is suitable for rigid PVC. Soft PVC, PA, PC, PE, PP and other plastic pipes.