Single Screw Extruder Knowledge-Part 3
The production capacity of the extruder is mainly related to the screw diameter, the screw speed, the length of the homogenization section, and the groove depth. The calculation of the extruder production capacity using the theoretical formula is complicated and can be calculated by means of the following empirical formula.
When the screw diameter is >90mm
When the screw diameter is ≤90mm
K-Empirical discharge factor, usually we use 0.3-0.7, use the smaller value when under the higher speed.
D-Screw diameter, cm
The extruder is mainly composed of screw, barrel, heating and cooling system, transmission system and control system.
The heating system for an extruder usually means the barrel, connect flange and die head heating.
Heater elements have different materials and shapes, usually like a ring or panel. It’s material includes High-efficiency ceramic, mica, cast aluminum, cast copper, electromagnetic, stainless steel, etc.
In daily working, the ceramic heater and cast aluminum heater usually adopted as barrel heating element, the stainless steel heater adopted for die head heating.
The barrel cooling mainly depends on the air blowing, it means the fan. Check the below drawing will get clearly.
Here has an important cooling which related with the extrusion capacity, it is the Hopper seat cooling system. It achieves by a water sleeve outside of the feeding section.
You may heard screw cooling before, but it mainly means the twin screw system, cause of the PVC extrusion process need control the screw temperature.
NEXT part we will learn the transmission system of the single screw extruder, it means the Gear Box.