Automotive battery pack sealing components are essential to guarantee the safe and reliable operation of new energy vehicle power batteries. Working in harsh environments with continuous vibration, drastic temperature changes and chemical erosion, these parts require excellent comprehensive performance including low compression deformation, high elasticity, wide temperature adaptability, flame retardancy and insulation. Professional high-precision molds, special modified materials and standardized injection molding processes are essential to produce sealing parts with stable structure, accurate size and long service life.
Material Selection and PreprocessingCommon raw materials for battery pack seals include liquid silicone rubber, EPDM rubber, fluororubber and glass fiber reinforced engineering plastics. Liquid silicone rubber is widely applied for its outstanding weather resistance, corrosion resistance and insulation, which can effectively resist battery electrolyte erosion and maintain stable sealing performance in long-term use. Other elastic materials and modified hard plastics are reasonably matched according to different installation positions and functional requirements to meet the assembly and use demands of different areas of the battery pack. Raw material pretreatment is the basic link to ensure molding quality. Elastic materials need precise proportioning and vacuum defoaming to remove internal bubbles, while engineering plastics must be strictly dehumidified and dried to control moisture content, avoid surface patterns, internal bubbles and mechanical property decline caused by moisture melting, and lay a foundation for stable injection molding.
Mold Structure Design
High-precision and high-rigidity mold design is the core of mass production of sealing parts. High-quality mold steel is selected for cavity and core, with fine surface polishing to ensure smooth sealing surface and prevent product burrs and scratches. The parting surface adopts high-precision matching design to control the gap within a reasonable range, effectively preventing overflow glue and short-circuit risks caused by tiny falling debris. The runner system adopts balanced layout to balance material flow pressure and speed, ensuring uniform filling of each area of the product. For special structures such as grooves and undercuts, reasonable core-pulling and demolding mechanisms are configured to avoid product deformation and damage during ejection. Meanwhile, independent and uniform temperature control circulating water channels are arranged to realize rapid and balanced cooling of the mold.
Injection Molding Process ParametersReasonable parameter setting can significantly improve molding quality and production efficiency. According to different material characteristics, stable material temperature, injection pressure and injection speed are formulated. Segmented speed control is adopted in the filling stage to avoid material turbulence and gas trapping caused by excessive shear. Appropriate holding pressure and holding time are set to supplement material shrinkage, stabilize product size and reduce surface shrinkage depression. For composite products with soft and hard bonding, regional temperature control is adopted to ensure the bonding firmness of different materials. The vulcanization and cooling time are accurately controlled to ensure complete material molding and rapid product shaping.
Defects and Quality Control
In actual production, common defects include flash, air bubbles, warping deformation and insufficient filling. By optimizing mold matching clearance, adjusting locking force and reducing molding pressure, the flash problem can be solved. Improving raw material defoaming effect, optimizing mold exhaust structure and matching reasonable injection speed can effectively eliminate air bubbles and trapped air scorching. Balanced cooling and optimized ejection structure help improve product warping and dimensional deviation. Strict finished product inspection is carried out to detect sealing performance, dimensional tolerance, corrosion resistance and flame retardant indicators, so as to ensure that all products meet the assembly and safety standards of automotive battery packs.
