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7.4.2.1.4 The combined effects

Consequently, a very small area ratio results in a very large resistance, and when therefore the resistance resulting in a zero gate velocity (like a closed valve). Conversely, for a large area ratio, the resistance is insensitive to variations of the gate area and the velocity is reduced with increase the gate area. Therefore a maximum gate velocity must exist, and can be found by

    (7.26)

which can be solved numerically. The solution of equation ([*]) requires full information on the die casting machine.

A general complicated runner design configuration can be converted into a straight conduit with trapezoidal cross-section, provided that it was proportionally designed to create equal gate velocity for different gate locations18. The trapezoidal shape is commonly used because of the simplicity, thermal, and for cost reasons. leave it for now, better presentation needed

Figure: Design and dimensions of the runner for the example [*]. The length, , represents different runner design qualities. The gate design is made of straight lines to the gate area, creating a symmetrical gate.

= 100 true mm

Figure: Gate velocities as a function of the area ratio for constant pressure.

= 100 true mm

Figure: Gate velocities as a function of the area ratio for constant power.


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