heating Fig. 8: Points temperature readings taken at Fig. 9: Temperature vs. Location - Water and electric heating with 1 hour soak the beginning, middle and end of each two-hour run with a surface pyrometer. A review of the temperature readings indicates that the water-heated runs were more consistent over the 2 hours. The average differential in temperature of the same location over the 2 hours in the water-heated runs was 1.94°C, while it was 6.7°C in the electrically-heated runs. A more relevant point is the difference in temperature over the length of a part. The average temperature differential over the length of one part at the same moment in time is 21.0°C for the electrically-heated trials. The average for the water-heated trials was only 2.7°C. This large temperature differential over the length of one part in the electricallyheated mould could create crystallinity changes within a part. This would create shrinkage differences throughout the part, resulting in a high degree of moulded-in stress. This stress could cause part warpage, creep and physical property Tab. 3: Data from test Fig. 10: Temperature vs. Location - Water and electric heating with 2 hour soak differences within the same part. In order to confirm an acceptable level of crystallinity, the parts were analyzed with differential scanning calorimetry (DSC) to determine their percent crystallinity. Temperature - °C Heat Type Part 2.54 mm thick Time Soak Temp. 1 Hour 2 Hours Soak Temp. 163.3 154.4 156.1 158.3 153.3 155.0 172.8 171.7 172.2 170.0 172.8 172.8 A 173.3 165.0 168.9 169.4 165.0 166.7 175.0 176.7 177.2 172.2 176.1 176.1 B 129.4 142.2 142.8 135.6 141.1 141.1 172.2 172.2 171.7 172.2 172.8 172.8 C 158.3 150.6 155.6 155.0 156.1 158.3 174.4 173.9 172.8 175.0 178.3 178.9 D 175.6 165.0 168.3 170.0 171.1 176.1 176.1 175.6 177.2 175.0 178.3 178.9 E 130.6 147.2 142.8 141.1 143.3 145.0 174.4 172.2 173.3 174.4 173.3 173.9 F 157.2 157.2 155.6 154.4 156.7 155.0 173.3 173.3 172.8 172.2 171.7 172.2 G 169.4 173.3 172.2 174.4 173.9 171.1 174.4 176.7 177.8 171.7 175.6 175.0 H 149.4 158.3 160.6 145.0 158.9 157.8 172.8 174.4 175.0 173.9 173.9 174.4 I 160.6 158.3 156.1 159.4 164.4 163.9 174.4 175.0 175.6 176.7 176.7 174.4 J 172.8 171.7 168.9 177.2 178.9 177.2 175.6 176.1 176.7 177.8 177.8 176.1 K 150.0 156.1 157.8 147.2 161.7 159.4 175.6 176.7 176.1 177.8 177.8 175.6 L Electric 5.08 mm thick 1 Hour 2 Hours Soak Temp. 2.54 mm thick Water 5.08 mm thick 1 Hour 2 Hours Soak Temp. 1 Hour 2 Hours Location 46 jec composites magazine / No75 August - September 2012