Micro Injection Molding Process Parameter Optimization

Micro injection molding is a highly precise processing method widely used in electronic components, medical devices, precision structural parts, and micro-optical components.Compared with traditional injection molding, micro-injection products feature extremely small size, ultra-thin walls, complex microstructures, and strict dimensional accuracy requirements.Therefore, systematic optimization of process parameters is essential to ensure molding quality, production stability, and product consistency.

Reasonable parameter settings can effectively reduce defects such as short shots, warpage, deformation, surface scratches, and poor structure replication, supporting stable mass production.

Temperature Control

Temperature control forms the foundation of stable micro injection molding.Barrel temperature must be set according to material characteristics to ensure complete melting without thermal degradation.Mold temperature directly influences cooling rate, internal stress, transparency, and dimensional stability.A suitable mold temperature helps reduce warpage and improve surface finish.Nozzle temperature must be coordinated with barrel temperature to prevent cold slugs, drooling, or blockage at the nozzle.Stable temperature control ensures consistent melt flow and reliable part quality.

Injection Pressure and SpeedInjection pressure and speed determine how the melt fills the micro-cavity.Due to small size and thin walls, micro parts require relatively high injection pressure to overcome flow resistance.Excessively high pressure may cause flash, high internal stress, and part brittleness.Insufficient pressure leads to short shots and incomplete filling.Injection speed is usually set in stages: low speed at the initial filling stage to prevent jetting and air traps, medium or high speed in the middle stage for fast and stable filling, and reduced speed at the end to minimize impact and stress.This staged setting improves filling stability and detail replication.

Holding Pressure and TimeHolding pressure and time compensate for volumetric shrinkage during cooling.Appropriate holding pressure reduces sink marks, shrinkage, and dimensional deviation.Excessively high holding increases wrapping force between the part and mold, causing demolding difficulties and sticking.Insufficient holding results in unstable dimensions and surface defects.Holding time should stop once the gate is sealed to avoid unnecessary residual stress.

For thick‑section micro parts, holding time can be extended slightly for better compensation.

Cooling and Metering Systems

Cooling performance directly affects production efficiency and part stability.Uniform cooling reduces temperature differences, uneven shrinkage, warpage, and internal stress.Cooling channels should be designed close to the cavity for efficient heat transfer.Cooling time must be balanced between sufficient solidification and productivity.The metering system controls the exact volume of melt injected per cycle.Stable metering reduces weight variation and ensures batch consistency.Common optimization methods include mold flow simulation, DOE testing, and on-site verification.Through comprehensive parameter adjustment, manufacturers improve qualification rates, reduce failures, and achieve efficient, stable micro injection production.