Through comprehensive structural design, mold optimization, injection molding parameter adjustment and plating process adaptation, the deformation risk of large-area thin plastic parts can be effectively reduced. Attention should be paid to multi-step verification, especially the matching of mold flow analysis and actual production parameters.
Author: Anna
I. Structural design optimization
Reinforcement and support structure
Design perimeter bars or bridge-shaped connecting bars in thin-walled areas to enhance overall rigidity and reduce deformation caused by internal stress; the height of the bars is recommended to be ≥2mm.
For plating requirements, add hook-up points and support structures on the plastic parts structure to ensure uniform force during plating.
Pre-deformation compensation design
According to the mold flow analysis to predict the direction of deformation, design the reverse convex structure in the mold to offset the shrinkage deformation (applicable to non-high-precision appearance parts).
II. Mold and injection molding process adjustment
Optimization of pouring system
Adopt multi-point glue feeding (e.g. three-plate mold), uniform filling to reduce the molecular orientation shrinkage differences; long and narrow parts can be unilateral glue feeding to reduce the difference in holding pressure.
The runner design is combined with support structure, and the runner is cut after plating to improve the overall strength of the injection molded part.
Cooling and holding pressure control
Extend the holding pressure time (10-15 seconds) and increase the holding pressure to reduce shrinkage; increase the mold temperature (e.g. ABS ≥60℃ is recommended) and reduce the cooling speed to ease the temperature difference deformation.
Optimize the cooling water circuit layout to ensure uniform cooling and avoid residual stress after demolding.
Demolding and molding process
After demolding, use the jig to set the shape while it is still hot to the touch to balance the rebound amount; need to study the over-pressing amount to offset the subsequent deformation.
III. Plating Process Adaptation
Hook-up and support design
Before plating, retain the injection molding runners as a temporary support structure to enhance the overall strength of the plating process, and remove the runners after completion.
Material and Parameter Adaptation
Prefer non-crystalline plastics with low shrinkage (e.g. ABS) to avoid deformation due to shrinkage difference of crystalline materials (e.g. PP, PE).
Through comprehensive structural design, mold optimization, injection molding parameter adjustment and plating process adaptation, the deformation risk of large-area thin plastic parts can be effectively reduced. Attention should be paid to multi-step verification, especially the matching of mold flow analysis and actual production parameters.