Meaning
The gradual erosion of the material around an injection mould orifice occurs due to the high-velocity flow of molten polymer or metal. Extensive gate wear changes the geometry of the entry point, leading to variations in pressure and fill time during the moulding process. This degradation is often accelerated by the use of abrasive fillers such as glass fibres or mineral powders.
It defines the point where a mould requires refurbishing or insert replacement to maintain part quality.
Orifice Erosion
Friction and thermal stress at the narrowest point of the flow path cause the removal of tool steel over thousands of cycles. When gate wear becomes excessive, the increased opening size lowers the shear heat generated during injection. This change can result in visible defects like gate blush or incomplete packing of the cavity.
Yield Degradation
Dimensional stability of the final product decreases as the inlet dimensions drift away from the original design. Monitoring gate wear allows a facility to predict when the scrap rate will exceed acceptable limits. A production run may start with high yields but deteriorate as the orifice enlarges and affects the cooling rate.
The cost of ignoring this wear includes both the wasted material and the potential for structural weaknesses in the finished parts.
Tooling Refurbishment
Hardened coatings or tungsten carbide inserts are frequently employed to extend the life of the mould in high-volume environments. Although these materials resist gate wear more effectively than standard tool steel, they eventually require inspection and replacement. Measuring the orifice dimensions at regular intervals provides the data needed for a predictive maintenance schedule.
Replacing an insert early is usually cheaper than repairing the entire mould plate after a catastrophic failure.
