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A. Demirer et al. / Materials and Design 28 (2007) 1467–1476 1469
Fig. 1. The drawing and the general view of injected part adopted in the study.
Table 1
Specifications of the moulding materials
Name of material Acrylonitrile butadiene styrene Polyprophylene
Symbol ABS PP
Commercial name Cycolac GE Petoplen MH418
Manufacturer GE Plastics Petkim A.S.
Resin type Amorphous Semi-crystaline
Density 1.05 g/cm3 0.91 g/cm3
Melt flow index 3.7 g/10 min (230 °C/3.8 kg) 4–6 g/10 min (230 °C/2.16 kg)
Process temperature 220–280 °C 170–260 °C
Tensile strength 17–58 MPa 30–40 MPa
Modulus of elasticity 2800 MPa 1250 MPa
moulding area for ABS and PP when using HRS and CRS (i.e., bottom in Fig. 2).
When using CRS, the flow of molten plastic becomes more difficult because of the heat dissipating in the runner channels. In addition, increase in flow length increases the frictional pressure losses. Using HRS provides significant
pressure gain by eliminating the disadvantages of CRS. PP material was injected at temperatures of 170, 200 and 260 °C, and at pressures shown on the diagram in Fig. 4. It was observed that significant pressure gain was provided when using HRS. At mean process temperature of 200 °C, e.g., the required average injection pressure is 70 MPa for
1470 A. Demirer et al. / Materials and Design 28 (2007) 1467–1476
Table 2
Experimental conditions for injection moulding process
Base polymer Process Injection pressure (MPa) Packing Mould Cycle Injection
temperature (°C) HRS CRS pressure (MPa) temperature ( °C) time (s) velocity (m/s)
ABS 225 60, 70, 75, 80, 90 70, 85, 95, 110 % 50 of injection 40 50 0.012
245 50, 65, 80 70, 100 pressure
260 40, 75 60, 90
280 30, 40, 60