Injection molding materials play a crucial role in industrial manufacturing, as their properties are directly related to product quality and market competitiveness. However, the common deformation problem during the injection molding process has become a major challenge for manufacturers. So, in the ever-evolving field of materials science, which injection molding materials can minimize deformation and become the key to improving product quality? This article will conduct an in-depth analysis of this topic, combined with the latest industry trends, to reveal the material selection for minimizing deformation in injection molded products.
Differences in the coefficient of thermal expansion of materials can lead to different dimensional changes when the temperature changes. In addition, the glass transition temperature is also an important consideration. When the ambient temperature approaches or exceeds this temperature, the physical properties of the material will change significantly, increasing the risk of deformation.
If the flow stress and cooling stress during the injection molding process are not effectively released, residual stress will be formed inside the material, causing the injection molded part to deform after demolding.
Some injection molding materials are sensitive to moisture, such as nylon. After absorbing moisture, the distance between molecular chains increases, the size expands, and the physical and mechanical properties also change, seriously affecting dimensional stability.
| Material Name | Shrinkage Rate | Moisture Absorption Rate | Heat Deflection Temperature | Coefficient of Thermal Expansion | Characteristics Overview | Applications Fields |
| Polycarbonate (PC) | 0.4%-0.8% | 0.12%-0.3% | 130 - 140℃ | Approximately 60 - 70×10⁻⁶/℃ | Transparent, oil-resistant, good mechanical properties | Construction, electronics, automotive, optics, medical, etc. |
| Polyphenylene Oxide (PPO) | 0.3%-0.8% | Approximately 0.06% | Glass transition temperature is approximately 210℃, melting point is 268℃ | Approximately 70×10⁻⁶/℃ | Excellent water resistance and electrical insulation, dimensional stability | Electronics, automotive, medical, etc. |
| Polyoxymethylene (POM) | 1.8%-3.5% | Very small | Can be used for a long time in the temperature range of -40℃ - 104℃ | Approximately 8.5 - 12.0×10⁻⁶/℃ | High elastic modulus, good crystallinity, wear-resistant. | Automotive, electronics, packaging, sports equipment, medical, etc. |
| Liquid Crystal Polymer (LCP) | 1.45%-1.7% | 0.02%-0.2% | 270 - 355℃ | 1 - 2×10⁻⁵/℃ | High precision, high strength, high heat resistance. | Aerospace, medical, automotive, electronic communication, etc. |
| Polysulfone (PSU) | 0.5%-0.7% | Low level | 160℃ | 5.6×10⁻⁵ cm/cm/℃ | Excellent chemical corrosion resistance | Food processing, medical, electronic appliances. |
| Polyetheretherketone (PEEK) | 1.3%-2.0% | ≤0.1% | 230℃ | Approximately (5 - 6)×10⁻⁵/℃ | Excellent thermal stability, good mechanical properties. | Aerospace, medical, automotive, electronic appliances, etc. |
According to product performance requirements, for example, in a high-temperature environment, materials with a high heat deflection temperature and a small coefficient of thermal expansion (such as LCP, PEEK) should be selected; for high-precision requirements, materials with excellent dimensional stability such as LCP should be given priority; in a humid environment, materials with a low moisture absorption rate (such as PPO, PSU) should be chosen; and for occasions in contact with chemicals, materials with strong corrosion resistance (such as PEEK, PSU) need to be used. When selecting materials, the balance between cost and performance also needs to be comprehensively considered.
Mold Design: Reasonably arrange the cooling channels and design appropriate gate positions and numbers to reduce stress concentration and ensure uniform filling.
Injection Parameter Adjustment: Optimize parameters such as temperature, pressure, and speed to improve filling performance and dimensional stability. At the same time, control the holding time and pressure to compensate for shrinkage.
Post-treatment Process: For high-precision products, annealing treatment can be used to eliminate residual stress; for materials with a high moisture absorption rate, drying treatment should be carried out.
Regularly use high-precision tools for dimensional measurement to ensure that the product meets the design requirements.
Conduct mechanical property tests to reflect the material properties and product quality and indirectly evaluate the dimensional stability.
Real-time monitor the key parameters and strictly inspect the quality of the raw materials to ensure the stability and controllability of the production process.
This article has revealed the material selection for minimizing deformation in injection molded products by in-depth analysis of the core factors affecting the deformation of injection molding materials and combined with the latest industry trends. At the same time, this article also provides professional material selection principles, process optimization strategies, and quality control methods, aiming to provide comprehensive and practical guidance for manufacturers and help improve product quality and market competitiveness.
Copyright © 2023 ：Worldbound Plasitc Products Co.Ltd
