The choice of plastic materials plays a key role in a plastic injection molding project, as it is directly linked to the technical characteristics expected from the product. That’s why it is important to ask the right questions at the beginning of a project.
Before choosing the right plastic material for molding injection, here are the questions to ask:
Here are the main polymers used in plastic injection molding:
| Plastic Material | Main Characteristics | Disadvantages | Typical Applications | Shrinkage Rate |
| PE (Polyethylene) | Impact and chemical resistant, flexible or rigid depending on the type, good durability. | Low temperature resistance, not very rigid. | Plastic bags, bottles, pipes. | Between 1.5% and 3% |
| PP (Polypropylene) | Lightweight, good chemical and thermal resistance, rigid or flexible, low water absorption. | Brittle at low temperatures, ultrasonic welding impossible, UV sensitive, low abrasion resistance. | Automotive parts, hinges, non-woven fabrics, electrical applications, food containers. | Between 1.5% and 2.5% |
| PS (Polystyrene) | Transparent, good thermal insulation, low cost. | Brittle, poor heat resistance, low impact resistance, poor solvent resistance. | Disposable cups, CD cases, insulation, appliances. | Between 0.4% and 0.8% |
| ABS | Strong, rigid, good thermal and mechanical resistance, lightweight, good dimensional stability, food grade. | Poor chemical resistance, electrostatic, poor UV resistance, toxic fumes at high temperature. | Toys (Lego), dashboards, casings. | Between 0.4% and 0.8% |
| PVC (Polyvinyl Chloride) | Weather-resistant, electrical insulator, rigid or flexible. | Releases toxic gases when burned, difficult to recycle, heat sensitive. | Windows, cables, pipes. | Between 0.3% and 0.6% |
| PET (Polyethylene Terephthalate) | Transparent, ideal for food containers, easily recyclable. | Sensitive to hydrolysis at high temperatures, requires drying before molding. | Bottles, food packaging. | Between 2% and 4% |
| PA (Polyamide / Nylon) | Wear-resistant in harsh environments, good mechanical properties. Reinforced with glass fiber for increased strength, suitable for high-durability and aesthetic parts. | High shrinkage rate, absorbs moisture. | Bearings, gears, technical textiles, electrical insulation sleeves. | Between 0.5% and 2% |
| PC (Polycarbonate) | Good mechanical resistance, especially in harsh environments. High electrical and thermal insulation, good glass substitute, excellent impact resistance. | Harmful to humans, poor chemical resistance, expensive, easily scratched. | Unbreakable windows, glasses, discs. | Between 0.5% and 0.7% |
| POM (Polyacetal C or H) | Very good dimensional stability and mechanical resistance. | Flammable, UV sensitive, possible degradation at high temperature. | Precision parts, gears. | Between 1.5% and 2.5% |
| PMMA (Polymethyl Methacrylate “Plexiglas”) | Transparent, rigid, UV resistant, excellent glass substitute, good mechanical resistance. | Brittle, scratch-prone, poor performance in extreme temperatures. | Glazing, light signs, optics. | Between 0.2% and 0.8% |
| TPE (Thermoplastic Elastomer) | Rubber alternative. | Seals, flexible tubes, bumpers. | Between 0.5% and 2% | |
| TPU (Thermoplastic Polyurethane) | Flexible, abrasion, compression, and chemical resistant. | High cost, moisture sensitive, complex to process. | Soles, phone cases, flexible pipes. | Between 0.5% and 2.5% |
| PBT (Polybutylene Terephthalate) | Good electrical insulator, good thermal resistance up to +150°C. | Brittle to impact at low temperature. | Connectors, electrical casings, coils. | Between 1.5% and 2.8% |
| PEEK (Polyether Ether Ketone) | Excellent mechanical and chemical resistance, very recyclable. | Expensive, complex processing. | Medical implants, aerospace parts, guide rings. | Between 1% and 1.8% |
| SAN (Styrene-Acrylonitrile) | Transparent, scratch and chemical resistant. | Low thermal and solvent resistance, difficult to process. | Household items, cosmetic packaging. | Between 0.5% and 0.7% |
| PPS (Polyphenylene Sulfide) | High heat resistance, melting point at +300°C. | Connectors, coil bodies. | Between 0.5% and 0.7% |
Other Characteristics of Polymers :
| Plastic Material | Recommended Thickness (in mm) | Flammability Rating | Shrinkage Rate | Operating Temperature |
| PE (Polyethylene) | 1.5 mm – 2.5 mm | Highly flammable (UL94 HB) | 1.5% to 3% | -50°C to +80°C |
| PP (Polypropylene) | 1.5 mm – 2.5 mm | Highly flammable (UL94 HB) | 1.5% to 2.5% | 0°C to +100°C |
| PS (Polystyrene) | 1.2 mm – 3.0 mm | Highly flammable (UL94 HB) | 0.4% to 0.8% | 0°C to +70°C |
| ABS | 1.2 mm – 3.5 mm | Flammable (UL94 HB to V-0 depending on formulation) | 0.4% to 0.8% | -20°C to +80°C |
| PVC (Polyvinyl Chloride) | 1.0 mm – 3.0 mm | Low flammability (self-extinguishing, UL94 V-0) | 0.3% to 0.6% | -20°C to +60°C |
| PET (Polyethylene Terephthalate) | 1.0 mm – 5.0 mm | Moderately flammable (UL94 V-2) | 2% to 4% | -40°C to +115°C |
| PA (Polyamide / Nylon) | 1.2 mm – 5.0 mm | Flammable (UL94 HB to V-2) | 0.5% to 2% | -40°C to +100°C |
| PC (Polycarbonate) | 1.2 mm – 3.0 mm | Low flammability (UL94 V-0) | 0.5% to 0.7% | -40°C to +120°C |
| POM (Polyoxymethylene / Acetal) | 2.0 mm – 10.0 mm | Highly flammable (UL94 HB) | 1.5% to 2.5% | -40°C to +100°C |
| PMMA (Polymethyl Methacrylate / Plexiglas) | 2.0 mm – 15.0 mm | Highly flammable (UL94 HB) | 0.2% to 0.8% | -40°C to +90°C |
| TPE (Thermoplastic Elastomer) | 1.0 mm – 8.0 mm | Variable (typically UL94 HB) | 0.5% to 2% | -30°C to +100°C |
| TPU (Thermoplastic Polyurethane) | 1.0 mm – 5.0 mm | Flammable (UL94 HB to V-2 depending on grade) | 0.5% to 2.5% | -40°C to +80°C |
| PBT (Polybutylene Terephthalate) | 1.0 mm – 5.0 mm | Moderately flammable (UL94 V-0 with additives) | 1.5% to 2.8% | -30°C to +140°C |
| PEEK (Polyether Ether Ketone) | 1.0 mm – 10.0 mm | Very low flammability (UL94 V-0, highly resistant) | 1% to 1.8% | -60°C to +250°C |
| SAN (Styrene-Acrylonitrile) | 1.5 mm – 5.0 mm | Flammable (UL94 HB) | 0.5% to 0.7% | 0°C to +90°C |
| PPS (Polyphenylene Sulfide) | 0.8 mm – 5.0 mm | Low flammability (UL94 V-0) | 0.5% to 0.7% | -50°C to +200°C |