Application example of injection molding spacer cooling water channel
In precision injection molding production, the design of the cooling system directly affects product quality and production efficiency. The spacer-type cooling water channel, with its efficient heat exchange capacity, has shown significant advantages in the processing of complex plastic parts. Take the injection molding of the automobile instrument panel frame as an example. This part uses PP+GF30 material and its structure includes multiple ribs and clips. Traditional straight-through water channels are difficult to cover special-shaped areas, resulting in uneven cooling and prone to warping and deformation of plastic parts. The qualified rate is only 72%. After the introduction of the spacer-type cooling water channel, by setting multiple sets of copper spacers inside the mold cavity, the water channel is divided into series diversion areas, so that the cooling water forms turbulence in the areas with dense ribs, the heat exchange efficiency is improved by 40%, the cooling time is shortened from the original 45 seconds to 28 seconds, and the qualified rate jumps to 96%.
The trend toward thinner-walled electronic device casings places higher demands on cooling speeds. A certain brand of laptop casings uses ABS+PC material, with a thickness of only 1.2mm. Traditional cooling methods are prone to internal stress due to local temperature differences. In this scenario, the spacer-type cooling water channel solves this problem through a “maze-like” layout: 0.8mm-thick beryllium copper spacers are placed on the movable side of the mold, dividing the water channel into eight independent circulation units, each corresponding to a different curved area of the casing. Actual production data shows that the cooling water flow rate deviation within each unit is controlled within 5%, and the temperature difference does not exceed 2°C. The internal stress value of the plastic part after demolding is reduced to below 15MPa, far below the industry standard of 25MPa, effectively preventing cracking during later assembly.
The injection molding production of medical devices has strict requirements for cooling uniformity. The connector of a certain infusion pump is made of PP material, and the inner wall must remain smooth and free of sink marks. Because traditional cooling water channels cannot be close to the curved surface of the inner wall, the connector port cools slowly and shows obvious sinking. The technical team combined the spacer-type water channel with the conformal design and embedded 316 stainless steel spacers in the mold cavity to control the distance between the water channel and the inner wall of the plastic part to within 1.5mm. At the same time, the water flow is guided to form a spiral flow through the guide holes on the spacer. After the transformation, the cooling time of the connector was reduced by 12 seconds, and the sink mark depth was reduced from 0.3mm to 0.05mm, which fully meets the appearance standards of medical-grade products. The defective rate of the production batch was reduced from 8% to 0.5%.
During the injection molding process of large household appliance plastic parts, such as washing machine panels, spacer-type cooling water channels demonstrate excellent batch stability. This component, measuring 800×500mm and made of HIPS material, suffers from uneven water flow distribution in traditional cooling systems, resulting in shrinkage differences of up to 1.2% between different mold runs, impacting assembly accuracy. By installing partitioned spacer water channels on the fixed mold side, the panel is divided into three cooling zones: edge, middle, and corner. Each zone is equipped with an independent temperature sensor and flow control valve. In actual use, the water temperature fluctuation in each zone is controlled within ±1°C, the shrinkage difference between different mold runs is reduced to 0.3%, and the component matching degree on the assembly line is improved to 99.2%, significantly reducing the frequency of subsequent mold repairs.
In the field of two-color injection molding, the application of spacer-type cooling water channels effectively solves the cooling adaptation problem of different materials. A mobile phone shell adopts PC+TPU two-color injection molding. The TPU soft glue part is prone to poor adhesion with the PC hard glue due to its slow cooling speed. The technical team designed a replaceable spacer water channel on the soft glue cavity side, and changed the distance between the water channel and the cavity by adjusting the spacer thickness: the PC part maintains a distance of 2mm for rapid cooling and shaping, and the TPU part increases the distance to 3mm, and adjusts the water temperature to 5°C to achieve a balance in the cooling rate of the two materials. After the improvement, the bonding strength between the soft glue and the hard glue increased from 15N/cm to 28N/cm, meeting the drop test requirements, and the product’s weather resistance test pass rate increased from 75% to 98%.
