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# 7.1 Introduction

The diagram is the most common calculation, if any at all, are used by most die casting engineers. The importance of this diagram can be demonstrated by the fact that tens of millions of dollars have been invested by NADCA, NSF, and other major institutes here and abroad in the diagram research. The diagram is one of the manifestations of supply and demand theory which was developed by Alfred Marshall (1842-1924) in the turn of the century. It was first introduced to the die casting industry in the late'70s [#!poro:davis75!#]. In this diagram, an engineer insures that die casting machine ability can fulfill the die mold design requirements; the liquid metal is injected at the right velocity range and the filling time is small enough to prevent premature freezing. One can, with the help of the diagram, and by utilizing experimental values for desired filling time and gate velocities improve the quality of the casting.

In the die casting process (see Figure ), perhaps put this section in general discussion a liquid metal is poured into the shot sleeve where it is propelled by the plunger through the runner and the gate into the mold. The gate thickness is very narrow compared with the averaged mold thickness and the runner thickness to insure that breakage point of the scrap occurs at that gate location. A solution of increasing the discharge coefficient, , (larger conduits) results in a larger scrap. A careful design of the runner and the gate is required.

= 90 true mm

First, the ``common'' diagram1 is introduced. The errors of this model are analyzed. Later, the reformed model is described. Effects of different variables is studied and questions for students are given in the end of the chapter.

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