Meaning
Mechanical deformation of a machine or tool body occurs when it is subjected to the high clamping or injection forces of the moulding process. Minimizing structural frame deflection is essential for maintaining part quality, as any movement in the press can lead to variations in wall thickness or the formation of flash. Modern injection moulding machines are designed with high-rigidity castings to resist these forces.
Force Distribution
Clamping pressure is applied to the mould to keep it closed against the force of the incoming molten plastic. If the structural frame deflection is too high, the platens will bow, causing the centre of the mould to open slightly while the edges remain closed. This leads to non-uniform part dimensions and increased wear on the guide pins and bushings of the tool.
Tooling Protection
Excessive movement in the machine frame can also put an uneven load on the mould itself, leading to premature fatigue or cracking of the steel. Monitoring structural frame deflection using strain gauges allows the machine controller to detect if the clamp force is unbalanced. Correcting this issue usually involves adjusting the tie-bar tension or reducing the injection pressure.
Process Stability
Rigid frames provide the consistent environment needed for high-speed moulding.
