the clamping force, and satisfy the power requirements.

For these criteria the designer has to check the runner design to see if gate velocity are around the recommended range. A possible answer has to come from financial considerations, since we are in the business of die casting to make money. Hence, the optimum diameter is the one which will cost the least (the minimum cost). How, then, does the plunger size determine cost? It has been shown that plunger diameter has a value where maximum gate velocity is created.

General relationship between runner hydraulic diameter and plunger diameter.

A very large diameter requires a very large die casting machine (due to
physical size and the weight of the plunger).
So, one has to chose as first approximation the largest plunger
on a smallest die casting machine.
Another factor has to be taken into consideration is the scrap created in the
shot sleeve.
Obviously, the liquid metal in the sleeve has to be the last place to solidify.
This requires the biscuit to be of at least the same thickness as the
runner.

Therefore, the scrap volume should be

When the scrap in the shot sleeve becomes significant, compared to scrap of the runner

Thus, the plunger diameter has to be in the range of

To discussed that the plunger diameter should not be use as varying the plunger diameter to determine the gate velocity

copyright Dec , 2006

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