How to Choose the Right PVC Injection Molding Machine? A Practical Guide

Select the Correct Clamping Force

Clamping force must be sufficient to prevent flash while not being excessively oversized. A common rule is:

Required clamping force (tons) = Projected area (cm²) × 0.5–0.8 ton/cm² (for rigid PVC).

Oversizing by more than 30% increases energy consumption and equipment investment unnecessarily.

Use a Screw Designed Specifically for PVC

PVC requires a lower compression ratio and corrosion-resistant materials. Standard screws for PP or ABS are not ideal.

• Recommended compression ratio: 1.6:1 to 1.8:1
• Bimetallic screw and barrel for corrosion resistance
• Optimized mixing section to reduce shear heat

Using a general-purpose screw may shorten screw life by 20–40% when processing PVC due to acid release during melting.

Prioritize Precise Temperature Control

PVC decomposes if overheated. The machine should provide multi-zone barrel heating with control accuracy of at least ±1°C.

Stable temperature control reduces:

• Burn marks
• Black specks
• Material degradation

Evaluate Energy Efficiency and Long-Term Cost

Servo-driven hydraulic systems can reduce energy consumption by 30%–60% compared to conventional fixed-pump machines.

For a 300-ton machine operating 20 hours per day, annual electricity savings can exceed several thousand dollars depending on local energy rates. Over 5 years, this often offsets the higher initial purchase price.

Common Questions About PVC Injection Molding Machines

What temperature should PVC be processed at?

Most rigid PVC is processed between 160°C and 190°C. Exceeding 200°C may cause degradation.

Can a standard injection machine run PVC?

It can, but without a PVC-specific screw and corrosion-resistant barrel, wear and product defects are more likely.

How do I calculate the correct machine size?

Calculate projected area and multiply by 0.5–0.8 ton/cm² to estimate required clamping force.

Is servo energy-saving technology worth it?

Yes. Energy savings of 30%–60% typically justify the investment within 2–3 years.

How long does a PVC screw last?

With proper material and maintenance, 3–5 years under normal industrial production.

What are common PVC molding defects?

Black specks, burn marks, short shots, and flashing are the most common issues, usually related to temperature, clamping force, or screw design.