7.4.2.5 Machine size effect

The question how large the die casting machine depends on how efficient it is used. To maximized the utilization of the die casting machine we must understand under what condition it happens. It is important to realize that the injection of the liquid metal into the cavity requires power. The power, we can extract from a machine, depend on the plunger velocity and other parameters. We would like to design a process so that power extraction is maximized.

Figure: The reduced power of the die casting machine as a function of the normalized flow rate

Let's defined normalized machine size effect

(7.45)

make for the three function of the machine characteristic as question. Every die casting machine has a characteristic curve on the diagram as well. Assuming that the die casting machine has the ``common'' characteristic, , the normalized power can be expressed

(7.46)

where is the machine power normalized by . The maximum power of this kind of machine is at 2/3 of the normalized flow rate, , as shown in Figure . It is recommended to design the process so the flow rate occurs at the vicinity of the maximum of the power. For a range of 1/3 of that is from to , the average power is 0.1388 , as shown in Figure by the shadowed rectangular. One may notice that this value is above the capability of the die casting machine in two ranges of the flow rate. The reason that this number is used is because with some improvements of the the runner design the job can be performed on this machine, and there is no need to move the job to a larger machine²².