Injection molding materials play a crucial role in industrial manufacturing, their performance directly impacting product quality and market competitiveness. However, deformation, a common problem during the injection molding process, poses a major challenge for injection molders and manufacturers. So, in the rapidly evolving field of materials science, which injection molding materials can minimize deformation and become the key to improving product quality? This article will delve into this topic and, drawing on the latest industry trends, reveal the key to selecting materials that minimize deformation in injection molded products.
II. Key Factors Affecting Deformation in Injection Molding Materials
Temperature Factors: Differences in the thermal expansion coefficients of materials lead to varying dimensional changes with temperature. Furthermore, the glass transition temperature (GTT) is a key consideration. When ambient temperatures approach or exceed this temperature, the material's physical properties significantly change, increasing the risk of deformation.
Stress Factors: If flow and cooling stresses during the injection molding process are not effectively relieved, residual stresses will form within the material, causing deformation after demolding.
Moisture absorption: Some injection molding materials, such as nylon, are sensitive to moisture. Moisture absorption increases the distance between molecular chains, causing dimensional expansion and changes in physical and mechanical properties, seriously affecting dimensional stability.
III. Unveiling the Injection Molding Materials with Minimal Deformation
Based on in-depth research and extensive surveys, we have compiled the following list of injection molding materials that excel in the industry and exhibit minimal deformation:
Material Name
Shrinkage
Moisture Absorption
Heat Deflection Temperature
Coefficient of Thermal Expansion
Overview of Features
Applications
Polycarbonate (PC)
0.4%-0.8%
0.12%-0.3%
130-140°C
Approximately 60-70 × 10⁻⁶/°C
Transparent, oil-resistant, and with excellent mechanical properties
Architecture, electronics, automotive, optics, medical, etc.
Polyphenylene oxide (PPO)
0.3%-0.8%
Approximately 0.06%
Glass transition temperature approximately 210°C, melting point 268°C
Approximately 70 × 10⁻⁶/°C
Water resistance, excellent electrical insulation, and dimensional stability
Electronics, automotive, medical, etc.
Polyoxymethylene (POM)
1.8%-3.5%
Extremely low
Can be used in Long-term use in the -40°C to 104°C temperature range
Approximately 8.5 - 12.0 × 10⁻⁶/°C
High elastic modulus, good crystallinity, and wear resistance
Automotive, electronics, packaging, sports equipment, medical, etc.
Liquid Crystal Polymer (LCP)
1.45%-1.7%
0.02%-0.2%
270 - 355°C
1 - 2 × 10⁻⁵/°C
High precision, high strength, and high heat resistance
Aerospace, medical, automotive, electronic communications, etc.
Polysulfone (PSU)
0.5%-0.7%
Relatively low
160°C
5.6 × 10⁻⁵ cm/cm/°C
Excellent chemical resistance
Food processing, medical, electronic appliances, etc.
Polyetheretherketone (PEEK)
1.3%-2.0%
≤0.1%
230°C
Approximately (5 - 6) × 10⁻⁵/°C
Excellent thermal stability and excellent mechanical properties
Aerospace, medical, automotive, electronics, etc.
Note: The above data is compiled from a variety of sources, including professional literature, technical specifications provided by material suppliers, industry experience data from plastic product manufacturers, and professional databases.
IV. Professional Guide to Material Selection and Process Optimization
1. Material Selection Principles:
Based on product performance requirements, for example, materials with high heat deformation temperature and low thermal expansion coefficient (such as LCP and PEEK) should be selected for high-temperature environments; materials with excellent dimensional stability, such as LCP, should be prioritized for high-precision requirements; materials with low moisture absorption (such as PPO and PSU) should be selected for humid environments; and materials with high corrosion resistance (such as PEEK and PSU) should be selected for applications involving contact with chemical substances. When selecting materials, a comprehensive balance between cost and performance should also be considered.
2. Process Optimization Strategies:
Mold Design: Rationally layout cooling channels and design appropriate gate locations and numbers to reduce stress concentration and ensure uniform filling.
Injection Molding Parameter Adjustment: Optimize parameters such as temperature, pressure, and speed to improve filling performance and dimensional stability, while controlling holding time and pressure to compensate for shrinkage.
Post-Processing: For high-precision products, annealing can be used to eliminate residual stress; materials with high moisture absorption should be dried.
3. Quality Control:
Regularly perform dimensional measurements using high-precision tools to ensure product conformance to design requirements.
Perform mechanical property testing to reflect material properties and product quality, and indirectly assess dimensional stability.
Real-time monitoring of key parameters and strict inspection of raw material quality ensure the stability and controllability of the production process.
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