Slit runner

At this stage, one has to take into account the volume compressibility of the material, since upon feed-up the hold-on time of material under pressure is determined by compressibility and slow viscous flow. If the pressure of injection PQ is sufficiently high, then at this stage a liquid may be considered to be Newtonian with viscosity q ,. Keeping this in mind, we may state that the calculation given below will be applicable to various plastisols (of types I and II) with the only difference that for plastisol I q = const, while for plastisol II q = q. For the sake of simplicity, the analysis will be performed for the case of a flat mould filled through a slit runner (Fig. 10 a). 

As in Sect. 6.1, let us consider the injection moulding of a long thin plate through a slit runner, neglecting the resistance of the runner. Then Eqs. (4.12), (5.11), (5.12) for pressure distribution P(z, t), the motion of the averaged flow front h(t), and filling time will have the form ... 

Filling a Plat Nould Through a Slit Grate (Runner).101... 

Filling a Flat Mold through a Slit Gate (Runner)... 

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