Guide to Selecting Injection Molding Materials for Plastics

From smartphone cases to car dashboards and critical medical components, these seemingly different products may share a common manufacturing process - injection molding. The performance of these products often depends on the plastic materials selected. As experts in injection molding, Retlaw Industries has analyzed nine commonly used plastic materials, providing product designers and engineers with a comprehensive material selection guide.

Injection molding remains one of the most efficient and optimized methods for mass-producing identical plastic components. With plastics being used across various industries, each sector has unique requirements for chemical formulations. Retlaw Industries' professional design team helps clients identify the most suitable plastic materials for specific applications, whether it's ABS for electronic housings or Acetal (POM) for drawer handles.

Also known as plexiglass, acrylic is a hard, transparent plastic commonly used in electronic and automotive components. Its natural transparency and colorability make it ideal for everyday items like eyeglass lenses, acrylic paints, and even nail art. Acrylic can be colored to appear translucent or opaque.

• High transparency: One of the clearest plastics available
• Excellent weather resistance: Resists discoloration from moisture and UV exposure
• Chemical resistance: Unaffected by water, weak acids, and alkaline solutions
• High surface hardness: Good impact resistance and rigidity
• Dimensional stability: Predictable final product dimensions

ABS is among the most commonly used plastics in injection molding due to its wide temperature range, stability, and insulation properties. Found in products from LEGO bricks to electronic devices, tools, and home repair equipment.

• High impact resistance: Rubber formulation provides elasticity
• Surface hardness: Certain formulations offer high rigidity
• Chemical resistance: Resistant to alkalis, water, and most inorganic acids
• Uniform shrinkage: Good dimensional stability
• Wide temperature range: Heat-resistant and won't shatter in cold environments

The ideal choice when rigid, heat-resistant plastic is required. As a food-grade material, HDPE is commonly used for storage containers, kitchenware, and refrigerator shelves. It's also suitable for chemical containers like detergent and shampoo bottles.

• Sustainability: Made from 100% recyclable material
• Chemical resistance: Resists corrosion, rust, and other chemicals
• Heat resistance: Won't melt or corrode at high temperatures
• Food-grade: Safe for food packaging and equipment
• Cost-effective: Low production costs at scale

One of the most versatile injection molding materials, often combined with other materials to enhance properties. Its high melting point and low friction make it suitable for products ranging from ropes to reinforced automotive parts and clothing.

• Low friction: Doesn't heat up under high friction
• Chemical resistance: Resistant to chemical corrosion
• Wear resistance: Suitable for elastic applications and clothing
• Adaptability: Can be combined with various other plastic materials

This transparent, high-impact plastic is commonly used in eyewear applications, LED light pipes, transparent windows, and sports equipment.

• High impact resistance: Resists scratching and denting
• UV resistance: Won't corrode or discolor under UV exposure
• High transparency: Suitable for windows and lenses
• Chemical resistance: Resistant to chemical corrosion
• Rigidity: Ideal for eyewear and window applications

Also known as Ultem, this amorphous material offers exceptional heat resistance compared to other plastics. Its rigidity makes it ideal for medical devices, electronics, and industrial components.

• Rigidity: Hard plastic suitable for high-impact industrial applications
• Heat resistance: Won't melt or deform at high temperatures
• High tensile strength: Resists cracking or breaking in harsh environments
• Flame resistance: Non-flammable with low smoke production

Commonly known as Acetal, this semi-crystalline polymer features natural glossy surfaces, making it useful for automotive applications, home appliances, and electronics.

• Rigidity: Maintains strength without bending
• Impact resistance: Strong enough to withstand significant impacts
• Solvent resistance: Resists corrosion from chemicals and solvents
• Glossy surface: Naturally smooth and reflective

Similar to Acetal but with better chemical resistance and elasticity, PP is commonly used in food-related applications like kitchenware, dishwasher-safe dishes, and storage containers. Also used in toys, hard-shell luggage, and automotive exterior parts.

• Chemical resistance: Doesn't react with most alkalis and acids
• Fatigue resistance: Maintains shape after repeated bending
• High electrical resistance: Excellent insulation properties
• Elasticity: Can bend without breaking

This versatile polymer appears in various plastic and foam applications across industries. Its bending properties make it ideal for hinge applications in disposable food containers and bottles, as well as rigid foam insulation and laminate flooring.

• Optical clarity: Transparent resin for clear plastic products
• FDA-grade: Safe for food packaging and consumer materials
• Stability: Rigid material suitable for packaging
• Cost-effective: Low production costs at scale

With over 40 years of industry experience, Retlaw Industries has become a leader in thermoplastic injection molding. Equipped with 19 injection molding machines and operating from a 50,000-square-foot facility, the company continues to take on new project challenges.