- \n
- PC requires 120-150\u00b0C drying for 3-4 hours before molding<\/li>\n
- Melt temperature: 280-310\u00b0C depending on grade and flow length<\/li>\n
- Mold temperature: 80-120\u00b0C for dimensional stability<\/li>\n
- Wall thickness: 1.5-4.0 mm typical, avoid abrupt transitions<\/li>\n
- Avoid sharp corners and use 0.5-1.0 mm radii at gate locations<\/li>\n<\/ul>\n<\/div>\n
What Is Polycarbonate Injection Molding?<\/h2>\n
Polycarbonat<\/a>1<\/a><\/sup> injection molding is a processing method that forms PC resin into parts by melting, injecting into a mold, and cooling to achieve final dimensions. The Spritzgie\u00dfprozess<\/a>2<\/a><\/sup> for PC requires precise control because this amorphous thermoplastic has high impact strength, optical clarity, and heat resistance up to 135\u00b0C continuous use. Engineers choose PC when applications demand transparency, toughness, or dimensional stability.<\/p>\n
In our Shanghai facility, we process 400+ materials including multiple PC grades\u2014general purpose, flame-retardant, medical, and UV-stabilized variants. Each grade shifts processing windows slightly. We see flame-retardant PC needing slightly higher melt temperatures and longer cycle times due to additive content. Medical-grade PC requires stricter drying and sometimes dedicated drying hoppers to avoid contamination.<\/p>\n
The reality: PC is not forgiving. Unlike ABS or PP, small variations in drying time or melt temperature cause visible defects immediately. You get streaks, silvering, or brittle parts after one bad shot. That\u2019s why engineers who succeed with PC treat it as a high-precision process rather than generic thermoplastic molding.<\/p>\n
\n ![\"polycarbonate-injection-molding-applications\"](\"https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/03\/polycarbonate-injection-molding-applications.webp\")
Polycarbonate injection molded parts<\/figcaption><\/figure>\n The tradeoff is worth it. PC delivers properties few other materials match\u2014impact strength around 850 J\/m notched Izod, light transmission up to 90%, and good resistance to chemicals and flame. That combination makes it the go-to material for automotive headlight lenses, medical device housings, electronic enclosures, and safety glazing.<\/p>\n
How Do You Dry PC Before Molding?<\/h2>\n
Dry PC at 120-150\u00b0C for 3-4 hours using desiccant drying equipment before molding. PC absorbs moisture from air and hydrolyzes if processed wet, losing molecular weight and mechanical properties. The moisture content must be below 0.02% before feeding material into the hopper.<\/p>\n
Here\u2019s what happens when you skip drying: water reacts with PC chains at processing temperatures, breaking polymer bonds. The result is molecular weight reduction, loss of impact strength, and surface defects like silver streaks or splay. We see this failure mode constantly\u2014new teams rush PC into the machine, get cloudy parts with zero impact strength, and blame the material grade.<\/p>\n
Our standard drying protocol uses desiccant dryers at -40\u00b0C dew point. For standard PC grades, 120-130\u00b0C for 3 hours works. For high-heat or glass-filled PC, bump to 140-150\u00b0C for 4 hours. The key is maintaining temperature throughout the hopper, not just at the dryer outlet. Ambient moisture reabsorbs quickly\u2014leaving dried pellets exposed for even 30 minutes can push moisture back up.<\/p>\n
\n ![\"polycarbonate-pc-material-pellets\"](\"https:\/\/zetarmold.com\/wp-content\/uploads\/2026\/03\/polycarbonate-pc-material-pellets.webp\")
Polycarbonate resin pellets<\/figcaption><\/figure>\n Practical tip: use a moisture analyzer or a simple moisture content meter to verify drying before production starts. Don\u2019t rely on dryer setpoints alone. We\u2019ve seen dryers malfunctioning or thermocouples drifting, showing 130\u00b0C while actual material temperature is 90\u00b0C. That gap costs you one bad batch and lost production time.<\/p>\n
For high-volume production, consider hopper dryers with closed-loop moisture sensors. These add cost but prevent the single most common PC failure mode. In 20 years of molding PC, we estimate 70% of first-shot failures trace back to inadequate drying. Fix drying upfront, and half your PC problems disappear.<\/p>\n
\n