TPU car wrap film extruder screw barrel

TPU (thermoplastic polyurethane) screws are core components of injection molding or extrusion equipment specifically designed for processing TPU materials. Their design must take into account both material properties and processing requirements. The following is a summary of key information:

I. Key Screw Design Points
Structural Parameters

The recommended length-to-diameter ratio (L/D) is 16-20, and the compression ratio is 2.5-3.0. The design consists of a feeding section (0.5L), a compression section (0.3L), and a metering section (0.2L).

High torque is required to avoid speed fluctuations that can lead to uneven plasticization. Screws with short compression sections are not suitable due to the high shear forces.

Materials and Processing

Molten TPU is non-corrosive, so the screw does not require special alloy coatings, but chrome plating is required for wear protection.

The temperature control range is typically 190-220°C (hard alloys can reach 240°C). Precise control of the barrel and nozzle temperatures is required.

II. Application Scenarios
Injection Molding: Reciprocating screw injection molding machines are preferred to ensure melt uniformity and offer the advantages of low-temperature processing. Extrusion processing: For example, TPU cast film or solid strip production requires a highly transparent or wear-resistant screw barrel (e.g., a nitrided screw with a diameter of 35-350mm).