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Thermoset vs Thermoplastic: Process, Material & Finished Part Comparison



Introduction

In industrial plastic manufacturing, injection molding is divided into two core categories: thermoset molding and thermoplastic molding. Although both processes use injection machines to produce plastic parts, their material properties, molding principles, equipment settings, and final product performance are completely different.
Many engineers and purchasers confuse the two processes and mistakenly use ordinary plastic molding for high-temperature, insulating, and wear-resistant parts, resulting in deformation, failure, and short service life. This article clearly compares thermoset and thermoplastic molding in all dimensions to help you select the correct manufacturing process for your components.


1. Fundamental Material Difference

Thermoplastic (Ordinary Injection Material)

Thermoplastic materials include common plastics such as POM, PA, ABS, PP, PC, and PE. These materials feature a linear molecular structure.

  • Melts when heated, softens and flows

  • Hardens when cooled, shape is changeable

  • Reusable and recyclable

  • Physical change only, no chemical cross-linking


Thermoset Material (Bakelite / Phenolic / UF / Epoxy)

Thermoset materials include phenolic resin (Bakelite), UF urea-formaldehyde resin, epoxy resin, and thermosetting PU. During molding, the material produces irreversible chemical cross-linking and forms a stable 3D network structure.

  • Preheated in the barrel, completely cured in the hot mold

  • Cannot be melted or reshaped after curing

  • Turns carbonized under extreme high temperature instead of melting

  • Non-recyclable, permanent forming

Core difference: Thermoplastic molding is physical melting and cooling; thermoset molding is chemical curing and permanent shaping.


2. Injection Molding Process Difference

Thermoplastic Molding (Ordinary Molding)

Process principle: High-temperature melting + low-temperature cooling shaping

  • Barrel temperature: 180℃ – 280℃ (fully melt the plastic)

  • Mold temperature: 40℃ – 120℃ (cool and solidify)

  • Molding cycle: Short, 20–60 seconds

  • Fast mass production, high output

Thermoset Molding

Process principle: Low-temperature preheating + high-temperature mold curing

  • Barrel temperature: 80℃ – 120℃ (only preheat, avoid early curing)

  • Mold temperature: 160℃ – 200℃ (complete chemical curing)

  • Molding cycle: Longer, 60–180 seconds

  • Strict temperature and pressure control required

Simple rule: Thermoplastic uses “hot barrel + cold mold”; Thermoset uses “cold barrel + hot mold”.


3. Mold & Equipment Requirements

Thermoplastic Mold & Machine

  • Equipped with cooling water channels

  • Low working temperature, long mold life

  • General-purpose screw and injection system

  • Low failure rate, suitable for huge-volume production

Thermoset Mold & Machine

  • Equipped with electric heating or oil heating system

  • Requires high exhaust performance to avoid burning and bubbles

  • Special anti-curing screw design

  • Mold works under long-term high temperature, higher precision requirements


4. Finished Part Performance Comparison

Thermoplastic Parts

Suitable for general structural parts with ordinary working conditions.

  • Good toughness, bendable and impact-resistant

  • Low high-temperature resistance (usually below 120℃)

  • Easy to deform under long heat or pressure

  • Average wear resistance and insulation performance

  • Recyclable and low production cost

Thermoset Parts (Bakelite / Phenolic / UF)

Suitable for high-standard industrial precision components.

  • Excellent high-temperature resistance (180℃ – 300℃)

  • High hardness, strong compression resistance, no deformation under long load

  • Superior electrical insulation and flame retardant performance

  • Great oil resistance, aging resistance and chemical stability

  • Ultra-low shrinkage, excellent dimensional stability

5. Application Scenarios

Thermoplastic Applications

Daily consumer goods, equipment housings, common structural parts, low-temperature mechanical accessories.

Thermoset Applications

Professional industrial parts that require high safety and stability:

  • Gas spring wear-resistant bushings and guide sleeves

  • Electrical insulation components and switch parts

  • Automotive high-temperature and oil-resistant accessories

  • High-precision mechanical wear-resistant parts

  • Household appliance heat-resistant structural parts

Conclusion

Thermoplastic molding focuses onhigh speed, low cost and recyclability for general-purpose plastic products. Thermoset molding sacrifices production speed to achieve high temperature resistance, insulation, hardness, wear resistance and extreme dimensional stability.

For critical industrial components such as gas spring bushings and electrical insulating parts, thermoset injection molding is the only reliable process to ensure long-term stable performance.

Hitech(HK) International Limited specializes in precision thermoset injection molding, providing custom Bakelite and thermoset plastic parts for industrial, automotive and electronic industries.