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Pressure drop (bar)
Flow rate (kg/h)
Figure 5.38 Pressure drop for a noncircular channel with /?rh = 2.77 mm and n = 2.052
53.2 Mold Filling
As already mentioned, the mold filling process is treated extensively in commercial
simulation programs [15,16] and recently by BANGERT [18]. In the following sections the
more transparent method of STEVENSON [19] is given with an example.
53.2.1 Injection Pressure and Clamp Force
To determine the size of an injection molding machine for the production of a given
part, knowledge of the clamp force exerted by the mold is important, because this force
should not exceed the clamp force of the machine.
Injection Pressure
The isothermal pressure drop for a disc-shaped cavity is given as [19]
The fill time T is defined as [19]
The Brinkman number is given by [19]
2
6
LDPE
T = 270 0 R=3mm
C
L = 100 mm
(5.76)
(5.77)
(5.78)