PS-Chi Mei POLYREX PG-33

PS-Chi Mei POLYREX PG-33 Tooling & Optical Refraction Guide

Molding an amorphous standard GPPS like POLYREX PG-33 requires careful gating and slow ejection to prevent stress-induced cloudiness and brittle cracking:

• Weld Line & Haze Management: GPPS is highly amorphous, meaning it has low mold shrinkage (0.3% to 0.6%). However, knit lines (weld lines) will block light transmission and degrade optical cosmetics. Jucheng’s tooling division conducts Moldflow analysis to place gates strategically, eliminating visible weld lines in functional view areas.
• Tool Steel Selection & Polishing: To fully leverage PG-33’s high-brightness properties, we use premium S136 stainless steel mold inserts, mirror-polished with high-grade diamond paste. This ensures that the molded components emerge with flawless, glass-like clarity.
• Molding Process Parameters: Process temperatures are managed at 180°C–240°C (356°F–464°F). Mold temperatures are kept at 30°C to 50°C (86°F–122°F). Slower injection speeds and low packing pressures are implemented to prevent residual molding stresses, which would cause birefringence or rainbow effects.
• Precise & Gentle Ejection: Because GPPS is highly rigid and brittle (tensile elongation 2%), sharp ejector pins can crack parts during release. We machine draft angles of at least 1.5° to 2° and utilize wide stripper plates or air-assisted ejection to distribute demolding force evenly.