Reynolds Number

Flow Velocity

Polymer melt rheology employs this ratio to estimate the stability of laminar flow during high speed injection moulding cycles. High values lead to unstable flow fronts which generate surface defects like jetting or sharkskin marks on the finished part. Machine operators monitor the injection speed against the melt viscosity to prevent the onset of turbulence within the nozzle or gate.

Excessive shear rates cause local temperature spikes that degrade polymer chains and change the physical properties of the finished product.

Moulding Efficiency

Processing engineers use the relationship between throughput and viscosity to balance mould cavity filling against internal stress distribution. Achieving consistent laminar flow ensures that material cooling rates remain uniform across the entire part geometry. Parts moulded with optimal control over these forces exhibit lower internal strain and better dimensional stability after ejection from the tool.

Correct management of the fluid state at the gate reduces the likelihood of structural voids or uneven density gradients.

Economic Calculation

Regrind utilization alters the base viscosity of virgin resins and shifts the reynolds number during the plastication stage. Lowering the effective viscosity via additive loading or heat changes the window of operation for stable production runs. Accurate adjustments to injection profiles maintain part quality despite the natural variance inherent in recycled feedstocks.

This parameter dictates the physical limits of flow for any thermoplastic material under pressure.