PP 170 65, 75, 80, 90, 100,  110 80, 90, 100, 110,  120 40 60 0.015

200 40, 100 70, 100

260 30, 40, 60,  70 45, 60, 80

Fig. 2.  Produced samples related to the various MAD    regions.

HRS, instead of 85 MPa for CRS which means a pressure gain of 17.64%. The pressure gains at other process tem- peratures of 170 °C and 260 °C were  determined  as 7.5 and 20%, respectively. When considering the low peaks instead of the average values of the  injection pressure, it was   determined   that   the   pressure   gains   rose   up   to

18.75%,   42.85%   and  33.33%   at   170,   200  and   260 °C,

respectively. This reduction on injection pressure allows considerable saving in production costs and increases the lifetime of the mould and injection machine. Pressure gains obtained when using HRS for ABS and PP materials are presented in Table  3.

A. Demirer et al. / Materials and Design 28 (2007)   1467–1476 1471

Moulding Area Diagram forABS

290

280

270

260

250

240

230

220

20 30 40 50 60 70 80 90 100 110 120

Injection Pressure (MPa)

Fig. 3.  Moulding area diagram for ABS material when using HRS and CRS.

270

260

250

240

230

220

210

200

190

180

170

160

Moulding Area Diagram for PP

HRS CRS

20 30 40 50 60 70 80 90 100 110 120 130

Injection Pressure (MPa)

Fig. 4.  Moulding area diagram for PP material when using HRS and CRS.

Table 3

Injection pressure gain with the use of HRS for ABS and PP polymers

Base polymer Process temperature (°C) Injection pressure

gain with the use of HRS

(MPa) (%)

ABS 225 20 20.51

245 20 23.53

260 17.5 23.33

280 22.5