During the enterprise injection molding production process, torsion or twisting of products after ejection is a common quality defect of plastic products. It not only affects the appearance and precision of products, but may also result in failed assembly, seriously restricting production efficiency and product qualification rate.

        Aiming at such injection molding deformation problems, this paper analyzes the core causes and puts forward corresponding practical improvement measures, providing operational references for the quality control of injection molding production.

       The essence of product torsion and twisting deformation lies in abnormalities in key processes such as melt molding, cooling and demolding during injection molding, leading to uneven internal stress distribution or unbalanced external force on the product, which eventually presents torsion, twisting and warping after ejection.

      Summarized from production practice, such deformation problems are mainly related to the setting of injection molding process parameters, mold structure design and equipment operation status.

       The specific causes are as follows:

       From the perspective of injection molding process parameters, unreasonable settings are the main inducements for deformation:

       1. Excessive in-mold pressure will cause the melt to be over-squeezed in the mold cavity, leaving excessive internal stress in the product after molding; the release of stress after ejection will induce torsion or twisting.

       2.Insufficient holding pressure time leads to inadequate compaction of the melt inside the cavity, resulting in poor structural stability of the product and easy deformation after cooling.

       3. Insufficient cooling time means the product is not fully cooled and stabilized in the mold; it is highly prone to twisting after ejection due to external temperature changes and internal stress.

      4. Excessively high melt temperature results in excessive fluidity, irregular molecular arrangement during molding, uneven shrinkage after cooling, and increased internal stress that induces deformation.

       5.Forced demolding during production will directly cause torsion or twisting when the under-stabilized product is pulled by external force.

       6.Unreasonable mold structure design also leads to product deformation.

       7.Improper mold temperature control, whether excessively high or unevenly distributed, affects the cooling rate and shrinkage uniformity of the melt: high mold temperature prolongs cooling and stabilization time, while uneven mold temperature causes inconsistent shrinkage of different parts, leading to twisting.

        8.Improper gate location or insufficient gate number results in uneven melt filling, differential stress and shrinkage across the product, inducing torsion.

      9.Unreasonable ejection mechanism design also causes deformation: for example, uneven stress at ejection positions leads to local deformation during ejection; jamming of the ejection mechanism and forced ejection will directly cause severe twisting of the product.

      Irregular cross-sectional thickness design of the product causes excessive differences in cooling rates and inconsistent shrinkage, which is also an important cause of deformation.

      Based on practical production experience, the application of corresponding improvement measures can effectively reduce or eliminate product torsion and twisting deformation:

       In terms of optimization of injection molding process parameters

       1. Reduce the holding pressure and advance the holding pressure switching time to minimize the squeezing stress of the melt in the cavity and avoid residual stress.

      2. Extend the holding pressure time appropriately to ensure full compaction of the melt and improve the structural stability of the product.

      3.Prolong the cooling time to ensure sufficient cooling and stabilization of the product in the mold, reducing deformation caused by stress release after ejection.

      4.Lower the melt temperature and reduce the back pressure to optimize melt fluidity and molecular arrangement, avoiding uneven shrinkage caused by excessive temperature. Meanwhile, forced demolding is strictly prohibited; demolding shall be performed only after the product is fully stabilized.

     In terms of mold structure and equipment maintenance 

      1.For mold temperature issues, reasonably lower the mold temperature, inspect and adjust the mold temperature control system to ensure uniform mold temperature distribution and reduce cooling differences among product parts.

      2.For gate issues, optimize the gate location and increase the number of gates according to the product structure to ensure uniform melt filling and avoid excessive local stress.

      3.For the ejection mechanism, optimize the ejection positions and adjust the ejection force to ensure uniform stress during ejection. Meanwhile, conduct regular maintenance on the ejection mechanism, troubleshoot and resolve jamming problems in a timely manner to ensure smooth ejection.

      4. For irregular product cross-sectional thickness and mold-related problems, optimize the product wall thickness design through mold modification to ensure uniform thickness. Meanwhile, carry out comprehensive maintenance of the mold to guarantee the precision of the mold cavity and reduce deformation caused by mold factors.

        In summary, torsion and twisting deformation of products after ejection is the combined effect of process, mold and equipment factors. In actual production, it is necessary to comprehensively investigate the causes of deformation according to the product structure characteristics and production status, take targeted measures such as process optimization, mold modification and equipment maintenance. Meanwhile, strengthen inspection and control during production and adjust abnormal parameters in a timely manner, so as to effectively improve product molding quality, reduce deformation defects and ensure smooth production.