Core Design and Commissioning Essentials of Two-color Injection Moulds

Two-color injection molding can complete integrated forming of two-color splicing and composite overmolding structures, which is widely used in 3C products, home appliance parts and daily plastic accessories. Product quality is mainly determined by early mould design and on-site commissioning effect. Different from ordinary single-color injection moulds, two-color moulds have complex parting structures, high positioning precision requirements and strict standards for melt fusion effect. Only by following scientific design rules and mature debugging experience can we effectively avoid common defects such as assembly misalignment, flash, poor fusion, shrinkage deformation and unsmooth demoulding.

Overall Structural Design of Two-color MouldsSuitable injection equipment shall be selected according to product specifications, with thickened and high-strength standard mould bases adopted to resist high injection pressure and prevent template deformation in mass production. It is necessary to verify the installation size, rotating stroke and nozzle position of the machine in advance to ensure no structural interference during mould operation. Symmetrical double-cavity layout is mostly applied in cavity design, with unified reference datum and overall dimension. High-precision positioning pins and locking structures are reasonably arranged, and the matching clearance is strictly controlled within 0.01mm to ensure accurate alignment after turntable rotation and eliminate splicing deviation.

The parting surface shall be arranged away from visible appearance surfaces, and targeted sealing structures shall be set at secondary injection positions with reasonable assembly gaps reserved according to soft and hard rubber matching modes. All sealing surfaces need fine polishing to reduce flash generation while ensuring smooth exhaust inside the cavity. Two independent gating systems shall be arranged respectively for base material and surface layer material, with gate positions arranged away from stress areas and appearance surfaces to weaken obvious fusion lines. Hot runner structures shall be equipped with independent temperature control modules to adapt to different melting temperatures of raw materials.

Independent cooling water circuits are arranged for different forming layers to realize synchronous cooling of products. Dense water channels are arranged at thick glue positions to accelerate shaping speed and reduce deformation probability. The ejection system shall keep balanced force output, with evenly distributed ejector pins to avoid product whitening and distortion during ejection. Standard exhaust grooves are processed at filling ends and material fusion areas to discharge internal air smoothly and prevent material burning and bubble defects.

Field Commissioning Skills of Two-color MouldsComplete no-load test operation after mould installation to check the flexibility of rotating parts and the firmness of overall assembly, and calibrate the clamping force to avoid excessive force damaging the mould or insufficient force causing overflow. The commissioning shall start with primary injection base materials, with stable injection pressure and speed adopted to ensure full filling and regular product outline. The cooling time shall be reasonably controlled, and rotating operation can only be carried out after the base material is completely solidified, so as not to cause overall distortion of semi-finished products.

In the secondary injection stage, segmented speed regulation is adopted for filling, low-speed feeding is used in the early stage to prevent impact displacement of base materials, and stable pressure maintaining is carried out in the later stage to improve bonding compactness. The forming temperature shall be adjusted according to the shrinkage difference between the two materials to balance the cooling shrinkage rate and reduce assembly gaps. For products prone to cracking at bonding positions, appropriate textures can be made on the joint surfaces to enhance physical adhesion effect. During commissioning, timely optimize process parameters aiming at bad phenomena such as weld lines, color difference and surface flow lines to stabilize product appearance quality.

Daily Production MaintenanceRegularly check the positioning accuracy and lubrication state of rotating components to keep long-term operation precision. Classify and clean residual plastic materials to prevent raw material mixing from affecting product quality. Daily inspect the smoothness of ejection and core-pulling structures to ensure stable demoulding. Strictly unify raw material specifications and drying parameters, and reduce random adjustment of forming processes, so as to maintain stable batch production quality of two-color plastic parts.

SummaryThe stable production of two-color injection products depends on scientific and reasonable mould structure design and refined on-site process debugging. In the design stage, focus on optimizing positioning structure, cooling layout, gating system and exhaust design to eliminate hidden dangers of defects from the source. In actual production, follow the debugging logic of stabilizing base material forming first and optimizing surface material effect later, reasonably balance temperature difference and shrinkage difference, so as to effectively solve various forming problems, improve product yield and meet the stable mass production requirements of various two-color precision plastic parts.