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.
Volumetric Fill Rate
Meaning
Rate of material flow into a mould cavity represents the volume of molten polymer injected per second by the moving screw. This volumetric fill rate dictates the shear rate experienced by the resin as it passes through the gate and runner system. The value is calculated by multiplying the cross-sectional area of the injection cylinder by the linear velocity of the screw.
Velocity Parameter
High injection velocities ensure that the polymer does not freeze before the cavity is completely filled. Control of this volumetric fill rate allows the moulder to maintain a constant flow front velocity, which prevents surface defects like jetting or weld lines. Modern machines use closed-loop feedback to adjust the screw speed as the flow front expands.
Flow Behavior
Resistance to flow increases as the polymer melt enters narrower channels, changing the effective pressure required to maintain velocity.
Shear Limit
Exceeding the maximum recommended shear rate for a resin degrades the molecular structure, which weakens the mechanical properties of the finished component. Molders must balance the volumetric fill rate to avoid both premature freezing and shear degradation. When the fill rate is too low, the melt cools prematurely, leading to high internal stresses and surface blush.
Optimizing this parameter ensures a uniform density distribution and minimizes the occurrence of cosmetic blemishes across the entire production run.