High-performance semi-crystalline polymers typically have high glass-transition temperatures. This results in the need for high mold temperatures to ensure that an appro- priate level of crystallinity is established in the part. Polymers such as PPS, PEEK, PPA, SPS, and even some PET polyesters fall into this high-performance class where mold temperatures of at least 120 C (248 F) and as high as 200 C (392 F) are needed in order to achieve the desired structure.