There is a clear correlation between extrusion output and screw diameter, but it is not a simple linear relationship. Generally speaking, the larger the screw diameter, the more material can be conveyed and plasticized per unit of time, and therefore the greater the output will be. The following gives you a systematic description:

1. Basic relationship

Extruder output Q ∝ D² × n

D = screw diameter

n = screw speed (rpm)

Q = output (kg/h or t/h)

Since the cross sectional area of the screw for material transport is approximately proportional to D², an increase in diameter has a significant effect on the output.

Example:

A 50mm screw extruder may have an output of 60-100kg/h.

A 90mm screw extruder may produce 300-500kg/h.

The output of a 120mm screw extruder can reach 700~1000kg/h. 2.

2. Other Factors Affecting Output

In addition to the screw diameter, the following parameters also strongly affect the output:

L/D ratio L/D: the larger the L/D ratio, the more fully the material is plasticized, but the resistance is large, too long rather than affecting the output.

Screw structure: common general-purpose, barrier screw, mixing screw, etc., determines the plasticizing efficiency and output stability.

Speed n: increase speed can improve the output, but limited by the melt temperature and thermal stability of the material.

Material properties: PE, PP, etc. have good fluidity and high output; PET, PA, etc. have high moisture absorption or melt viscosity and low output.

Head resistance and mold design: the higher the resistance, the lower the output. 3.

3. Empirical formula (common industry experience)

In the plastic extrusion industry, the common experience formula is:

Q=k⋅D2⋅n

Q: output (kg/h)

D: screw diameter (mm)

n: screw speed (rpm)

k: empirical coefficient, range 0.0015 ~ 0.0035, depending on plastic type and screw structure.

👉 Summary:

Extruder output is directly proportional to the square of the screw diameter, and is also affected by screw speed, L/D ratio, screw construction, and material properties.

When selecting an extruder, it is important to look not only at screw diameter, but also at material type, product requirements, energy consumption, and stability.