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What Is Essential for A Good Table Mould Design?

   Essential for good Table Mould(FURNITUREMOULD) design for hot manifold operation is to balance the runner system and calculations that will effectively cool the cavity clusters. Thermal insulation of the thermal manifold is achieved by including an air gap and a minimum contact area between the hot and cold portions of the mould. Double the air gap interval can increase the insulation effect by 8 times. The hot runner plate must not contact the mould part in any way other than the minimum support area necessary to separate the parts.

Through asbestos, glass bonded mica is typically used to minimize heat transfer from hot parts to cold parts. Glass bonded mica is advantageous because it can be ground to absolute flatness and the same parallelism as steel, and it has overall dimensional stability of up to 700 °F. The differential expansion between the hot manifold element and the cooler table mould part must be allowed.

This is typically accomplished by arranging a sliding table mould portion between the manifold plate and the integrated gate plate. The flat floor provides the necessary sliding surface or a cylinder unit can also be used. Certain types of probes or hot tip bushings are used with the ring gate to maintain the temperature at the manifold outlet. The manifold and tip are heated to maintain the barrel temperature in the compound.

The minimum manifold area follows the cavity layout pattern and the manifold is cut into a minimum profile containing the flow channels and heating elements. Basic manifold design considerations include heaters that are parallel to the internal flow channel. Thermocouples that maintain the desired temperature are essential.

Since the hot tips are forwardly indexed by a cavity that is cooler than the manifold, they must move freely to compensate for their different expansions. A positive seal must be maintained between the bushing and the manifold. By sliding in the holes of the spruce bushing or nozzle and in the bore, the hot runner can freely expand in the direction of the fixed end. The slidable end is sealed by a specially designed metal seal.

In some cases, dispensing a wheel set may require an external heating tip from a controlled source, heating the probe, hot gate bushings, and heater castings are important to improve hot manifold forming. By heating the runner tip in the thermal control gate, the melting time is extended and the material does not freeze in the runner. The gate and probe are heated by encapsulation in a cast beryllium copper body or by the use of internal heating elements, and in some cases, thermocouples are also included.

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