Piezoelectric Cavity Pressure Telemetry in Injection Molded Parts
Wireless piezoelectric cavity pressure telemetry eliminates platen cabling, providing real-time process monitoring for active part quality containment.
Dimensional Stability
Meaning
Resistance of a plastic component to changes in its physical measurements during storage or service ensures the long-term assembly of multi-material systems. This dimensional stability governs the structural integrity of the part under changing temperature and humidity loads. The property is determined during the solidification stage of the injection molding cycle.
Material Specification
Resins with amorphous structures generally maintain their shape far better than semi-crystalline polymers because they lack a highly ordered, temperature-sensitive crystalline phase. Polymer selection must account for this, as materials like polycarbonate hold their shape under heat, whereas polyamides swell as they absorb atmospheric moisture. Glass fiber filler can be added to the formulation to reduce isotropic shrinkage and boost dimensional stability.
Shrinkage Influence
Insufficient packing during the hold phase produces uneven volumetric shrinkage across different regions of the part. This variance degrades the dimensional stability of the component, leading to warpage as the internal stresses relax over time.
Production Control
Stabilizing the mould temperature and extending the cooling time prevents post-mould distortion by allowing the polymer chains to lock into a stable state before ejection. Molders cannot rely solely on the datasheet value for dimensional stability, as the actual variation across a production run depends heavily on the consistency of the cooling circuit and the injection pressure. High-precision applications require a continuous monitor on gate freeze-off times to ensure each shot experiences the identical thermal history.