Screw and barrel clearance directly affects the plasticizing efficiency, output and stability of an extruder or injection molding machine.

After long-term operation, wear on the screw flights and barrel inner surface gradually increases the clearance. When the gap becomes too large, molten plastic can flow backward instead of moving efficiently toward the die or injection unit.

Common Signs of Excessive Screw and Barrel Clearance

Typical symptoms include lower production output, unstable extrusion or injection pressure, longer plasticizing time, higher melt temperature, poor mixing and increased energy consumption.

These problems are especially common when processing recycled plastics, glass-fiber reinforced materials or compounds containing high levels of CaCO3.

Why Correct Screw and Barrel Clearance Matters

Correct screw and barrel clearance helps maintain stable conveying, melting and pressure. Excessive wear can reduce production efficiency and affect final product quality.

Should You Repair or Replace the Screw and Barrel?

The screw diameter and barrel inner diameter should be measured at several positions and compared with the original specifications.

For minor wear, screw rebuilding may sometimes be possible. However, when both the screw and barrel are seriously worn, replacing them as a matched set can provide more stable clearance and longer service life.

For abrasive materials, a bimetallic barrel and wear-resistant alloy screw can help reduce future wear.

Need a Replacement Screw and Barrel?

Zhoushan Juyuan Plastic Machinery manufactures customized screw and barrel sets for extrusion and injection molding machines.

Send us your machine model, screw diameter, processed material or drawing for a quotation.

WhatsApp: +86 13905808474
Email: cxj.job@gmail.com
Website: juyuan-machinery.com