Plastic injection molding supports a wide range of thermoplastics and thermosetting polymers, each chosen based on properties like strength, flexibility, heat resistance, and cost. Below are the most commonly used types:
1. Thermoplastics (Most Common)
These plastics soften when heated and harden when cooled, making them recyclable.
a. Polypropylene (PP)
- Properties: Lightweight, flexible, chemical-resistant, and fatigue-resistant.
- Applications: Food containers, automotive parts, medical syringes, bottle caps.
b. Acrylonitrile Butadiene Styrene (ABS)
- Properties: Strong, impact-resistant, durable, and easily machinable.
- Applications: Automotive dashboards, electronic housings (laptops, TVs), LEGO bricks.
c. Polyethylene (PE)
- Types:
- High-Density Polyethylene (HDPE): Strong, chemical-resistant.
- Low-Density Polyethylene (LDPE): More flexible, lightweight.
- Applications: Bottles, containers, plastic bags, piping.
d. Polycarbonate (PC)
- Properties: High impact resistance, transparent, and heat-resistant.
- Applications: Eyeglass lenses, car headlight covers, safety helmets.
e. Nylon (Polyamide – PA)
- Properties: High strength, wear-resistant, and self-lubricating.
- Applications: Gears, bearings, automotive parts, power tool casings.
f. Polystyrene (PS)
- Types:
- General Purpose Polystyrene (GPPS): Hard, brittle, transparent.
- High-Impact Polystyrene (HIPS): Stronger, more impact-resistant.
- Applications: Disposable cutlery, CD cases, insulation foam.
g. Polyethylene Terephthalate (PET)
- Properties: Strong, lightweight, moisture-resistant.
- Applications: Beverage bottles, food packaging, synthetic fibers.
h. Polyvinyl Chloride (PVC)
- Properties: Chemical-resistant, durable, and flame-retardant.
- Applications: Plumbing pipes, cable insulation, medical tubing.
2. Thermosetting Plastics
Unlike thermoplastics, these plastics do not melt when reheated. Once set, they remain rigid.
a. Epoxy Resins
- Properties: High strength, chemical resistance, and electrical insulation.
- Applications: Circuit boards, adhesives, coatings.
b. Phenolic Resins (Bakelite)
- Properties: Heat-resistant, rigid, good electrical insulation.
- Applications: Electrical sockets, automotive parts, cookware handles.
c. Polyurethane (PU)
- Properties: Flexible, durable, impact-resistant.
- Applications: Foam cushions, automotive seats, seals.
