Keywords: TPE; Overmolding; Cracks; Warpage; High Shrinkage Defects such as cracks, warpage and high shrinkage in TPE overmolded products are closely related to the hardness, molecular structure and processing technology of TPE. The causes of defects in high-hardness TPE differ significantly from those in medium and low-hardness TPE. It is necessary to optimize the formulation and process by classification, and solve the problems on the premise of ensuring the core properties of the products (e.g., hardness, wear resistance, etc.). I. Core Causes of Such Defects in High Cross-Linking Degree & High Hardness TPE Overmolding Excessively high melt elasticity and concentrated internal stress, coupled with uneven cooling and shrinkage between thick and thin wall sections, lead to shrinkage cracks and warpage deformation of products after setting. The corresponding solutions are as follows: 1.Formulation Aspect Prioritize the use of star-type, high molecular weight SEBS; its three-dimensional branched structure can increase the entanglement density of molecular chains and form a stable cross-linked framework, which not only meets the requirement for high hardness but also reduces stress rebound, thereby mitigating the risk of cracks from the root cause. Meanwhile, replace conventional fillers with ultra-fine modified fillers—this modification can not only reduce melt viscosity and improve processing fluidity but also avoid local stress concentration caused by filler agglomeration, further inhibiting crack formation. 2.Processing Aspect Focus on alleviating internal stress and cooling discrepancies: reduce the melt temperature by 10℃ to mitigate the rebound stress caused by high-temperature orientation of molecular chains; appropriately increase the packing pressure and extend the packing time to compensate for the volume loss due to cooling shrinkage and offset internal stress; optimize the temperature-controlled water channels to ensure uniform temperature across all mold sections, eliminate cooling temperature differences between thick and thin wall areas, and resolve the warpage issue. II. Medium and Low Hardness TPE Overmolding Such defects stem from insufficient melt strength and weak molecular chain entanglement force. In addition, the relatively high oil content in medium and low hardness TPE further exacerbates melt instability, leading to abnormal shrinkage and surface sinkage after cooling. The solutions are as follows: 1.Formulation Aspect Follow the principle of "Maintaining Hardness while Reinforcing Melt Strength": Select linear medium-high molecular weight grades of SEBS and compound them with 5%~10% star-type SEBS. The star-type branched chains are utilized to form weak physical cross-linking points, which enhance the molecular chain entanglement force and melt anti-sinkage capacity without affecting hardness. Adopt ultra-fine flaky talcum powder as the filler; its dense overlapping network can restrict the cooling slip of molecular chains and reduce the shrinkage rate. Add a minimal amount of cross-linking agent to form a weak cross-linking network when necessary, and strictly control the dosage to avoid hardness increase, thus enhancing the shrinkage inhibition effect. 2.Processing Aspect Targeted inhibition of uneven shrinkage: Reduce the melt temperature by 15~20℃ to minimize molecular chain orientation and over-plasticization; increase the mold temperature to 40~50℃ to avoid sink marks caused by rapid surface setting of products and post-shrinkage of the internal structure; simultaneously raise the packing pressure and extend the packing time, and cooperate with the "slow-fast-slow" staged injection process to continuously replenish material into the mold cavity, ensure full melt filling, and minimize the defects of shrinkage and sinkage to the greatest extent.