It's important to choose the right material for the injection molding projects. There are a wide range of injection molding materials available, and we will discuss 10 popular injection molding materials as well as their properties and applications in the article.
Popular Injection Molding Materials
Nylon(PA)
Acrylic (PMMA)
ABS
Polycarbonate (PC)
Polyethylene (PE)
Polyether Ether Ketone (PEEK)
Polyoxymethylene (POM)
Polypropylene (PP)
Polystyrene (PS)
TPU
Nylon (PA)
Properties
Nylon is a family of synthetic polymers with amide backbones, which can be melt-processed into fibers, films, and diverse shapes. It is characterized by high strength and temperature when reinforced. It also has high chemical resistance, but it lacks strong resistance to strong bases or acids. However, this material is prone to shrinkage and is subject to inadequate mold filling during injection molding. It is not ideal for the production of marine applications due to absorbing water.
Grades and Brands

  • Nylon 6

  • Nylon 6/6

  • Nylon 66

  • Nylon 6/66

Applications

  • Combs

  • Cameras

  • Quick-release buckle

  • Hand cranks

  • Spools

  • Gears

  • Bearings

  • Bushings

  • Slides

  • Screws

  • Structural parts (with glass)

  • Pump parts

  • Under-hood components

  • Wear pads

  • Guide wheels

  • High-ware parts

Acrylic (PMMA)
Acrylic (PMMA) is a transparent and durable thermoplastic with resistance to ultraviolet (UV) light and weather. So it is a great choice for outdoor applications. The material is often used as a alternative to shatterproof glass because it is a non-crystalline vitreous substance. It has a density of 1.17–1.20 g/cm3, making the material tough but lightweight. Compared with glass, PMMA is softer and more easily scratched. Therefore, it requires the addition of scratch-resistant coatings to protect itself and enhance specific properties such as impact resistance, flame retardancy, chemical resistance or UV light filtering. However, PMMA is prone to cracking under heavier loads and has low impact resistance. It is easily to be attacked by organic solvents as well.
Grades and Brands
Grades

  • General-purpose acrylic

  • Sign-grade acrylic

  • Marine-grade acrylic

Brands

  • Crylux

  • Hesalite

  • Plexiglas

  • Acrylite

  • Lucite

  • Perspex

Applications

  • Light pipes

  • Lenses

  • Light shades

  • Optical fibers

  • Signs & displays

  • Interior and exterior panels

  • Bumpers

  • Fenders

  • Windows

  • Appliances

  • Furniture

  • Dental equipment

  • Medical storage devices

ABS
Properties
ABS is an opaque thermoplastic polymer made by polymerizing  styrene and acrylonitrile in the presence of polybutadiene.
Compared with other common polymers, it boasts good impact resistance, dimensional stability, toughness, and rigidity.
The durable and lightweight material can be easy to mold because of its relatively low melting point. However, it is not suitable for outdoor applications because it provides poor resistance to sunlight (UV), water, and weather.
Grades and Brands

  • Samsung Starex

  • Toray Toyolac

  • BASF Terluran

  • Ineos Lustran

Applications

  • Electronics

  • Keyboard keys

  • Phone adaptors

  • Phone hardware

  • Protective headgear

  • Electrical outlet wall plates

  • Wall socket plastic guards

  • Automotive parts like wheel covers

  • Consumer goods

  • Kitchen appliances

  • Sports equipment

  • Industrial fittings

  • LEGO bricks

  • Drainpipe systems

Polycarbonate (PC)
Properties
PC is a transparent and engineering-grade thermoplastic with excellent optical properties, good electric insulation and decent abrasion resistance. It has low shrink, good dimensional stability, great heat resistance and impact resistance. Polycarbonate can hold up longer to extreme temperature and undergo large plastic deformations without cracking or breaking. However, it has poor chemical resistance and is not a good choice for parts with thick geometries, which could cause voids, bubbles, and sinks.
Grades and Brands

  • SABIC Lexan (flame-resistant versions)

  • Covestro Makrolon (glass-like transparency)

Applications

  • Lenses

  • Indoor and outdoor lighting

  • Safety helmets

  • Cell phone housings

  • Equipment housing

  • Electrical components

  • Automotive parts

  • Medical devices

  • Bulletproof glass

  • Clear molds for urethane and silicone casting

Polyethylene (PE)
Properties
Polyethylene (PE) is the most commonly produced plastic with superior chemical resistance. It is a good electrical insulator. It absorbs virtually no water and has lower gas and water vapor permeability (polar gases only) than most plastics.It is inexpensive but limited to indoor applications due to its poor UV resistance. It can be divided into several types by its density and branching, which are different in hardness, flexibility, melting point, and optical transparency.
Grades and Brands

  • UHMWPE

  • ULMWPE or PE-WAX

  • HMWPE

  • HDPE

  • HDXLPE

  • PEX or XLPE

  • MDPE

  • LLDPE

  • LDPE

  • VLDPE

  • CPE

Applications

  • Consumer plastic parts

  • Containers

  • Packaging

  • Plastic bottles

  • Trash cans

  • Toys

  • Housewares

  • Automotive parts

  • Corrosion-resistant piping

  • Plastic lumber

  • Laboratory equipment

  • Molding liners for tanks and ponds

PEEK
Properties
PEEK is a colourless organic thermoplastic polymer, which is one of the most versatile and popular injection molding resins. It has high chemical resistance, excellent dimensional stability, high energy radiation and low smoke emission. It’s a durable and wear-resistant material with flexibility in applications. It is suitable for aerospace, automotive, and chemical industries. However, it is expensive and may be not worth considering if price is a great concern.
Grades and Brands
PEEK can be divided into both general and brand-specific grades . Here are four primary PEEK grades across industry:

  • Unfilled PEEK

  • 30% glass filled PEEK

  • 30% carbon filled PEEK

  • Bearing grade PEEK (also known as PTFE PEEK, carbon fiber-reinforced with graphite PEEK, Ketron® HPV, etc.)

Applications

  • Bearings

  • Gears

  • Piston/pump components

  • Cable insulation

  • Fasteners for electronic devices

  • Semiconductor manufacturing equipment

  • Surgical instrumentation

  • Manifolds

  • Medical implants

  • Automobile components

  • Aerospace components

  • FDA-compliant food contact equipment

Polyoxymethylene (POM)
Properties
POM is a popular engineering thermoplastic characterized by high strength, hardness and rigidity. It has good lubricity, resistance to hydrocarbons and organic solvents, low creep and great fatigue properties. Therefore, the material is often used to produce precision parts requiring high stiffness, low friction, and excellent dimensional stability. However, its outdoor applications are limited because of lacking resistance to sunlight.
Grades and Brands

  • Delrin

  • Kocetal

  • Ultraform

  • Celcon

  • Ramtal

  • Duracon

  • Kepital

  • Polypenco

  • Tenac

  • Hostaform

Applications

  • Gears

  • Pumps and pump impellers

  • Fan and blower blades

  • Automotive switches

  • Electrical switch components

  • Fasteners

  • Parts for knives and firearms

  • Bearings

  • Conveyor belts

  • Pulley wheels

  • Eyeglass frames

Polypropylene (PP)
Properties
Polypropylene (PP) is a recyclable thermoplastic polymer that has high chemical, glue and moisture resistance. The material has a low density and good resistance to fatigue. It is a tough and flexible material with incredible impact strength and elasticity. However, it exhibits poor resistance to strong oxidants. It is flammable and hard to paint over.
Grades and Brands

  • Pure polypropylene( commodity plastic the lowest density)

  • High crystalline polypropylene (HcPP) (filled with glass fibers for rigidity.)

  • Semitron® from Mitsubishi Chemical Advanced Materials (popular brand)

Applications

  • Power tool bodies

  • Hinges

  • Pipes

  • Laboratory equipment

  • Medical pipette tubing

  • Storage containers

  • Appliances

  • Packaging

  • Pallets

  • Snap-over lids (e.g., shampoo bottle tops)

  • Toys

  • Sporting goods

Polystyrene (PS)
Properties
Polystyrene (PS) is a transparent and lightweight synthetic polyme made from monomers of the aromatic hydrocarbon styrene, which is relatively inexpensive and rigid. It is a good electrical insulator and has high optic clarity. Despite being easy to mold and process, the material has poor chemical resistance. It is brittle, flammable and susceptible to UV degradation. Depending on the type, PS can either be classified as High Impact Polystyrene (HIPS) or General Purpose Polystyrene (GPPS).
Grades and Brands

  • American Styrenics PolyRenew

    ®

  • BASF Polystyrol

    ®
Applications

  • Packaging

  • Cutlery

  • Containers

  • Trays

  • Toys

  • Cassette cases

  • Electronic housing

  • Glazing

  • Tool cases

  • Plastic utensils

  • Optics

Thermoplastic Polyurethane (TPU)
Properties
Thermoplastic polyurethane elastomer (TPU) is a type of elastomer that can be plasticized by heating and dissolved by solvents. It has many properties such as transparency,high strength, and resistance to oil, grease, and abrasion. The material also has good load-bearing capabilities, elasticity and processing performance. It is resistant to low temperature and can withstand exposure to ozone. However, thermoplastic polyurethane elastomer (TPU) has a higher cost and shorter shelf life than other alternatives.
Grades and Brands
Grades

  • Commercial

  • Medical

  • Industrial

Leading Brands

  • Lanxess

  • Lubrizol

  • Texin

  • Ultralast

Applications

  • Footwear

  • Gaskets

  • Caster wheels

  • Sporting goods

  • Cases or enclosures for electronics and medical device

  • Protective wire and cable sheaths

Comparing Injection Molding Materials
Moulding Materials
Max Temp
Chemical resistance
Tensile strength
Flexural strength 
Impact strength
Acrylonitrile Butadiene Styrene (ABS)
60 – 93℃
Poor to fair
6,600 psi
270,000 – 380,000 psi
3.0 – 7.5 ft-lb/in
Nylon
93 – 177℃
Good to excellent
6,000 – 24,000 psi
390,000 – 1,100,000 psi
2 – 8 ft-lb/in
High density Polyethylene (HDPE)
120℃
Good to excellent
3,200 – 4,500 psi
145,000 – 225,000 psi
0.4 – 4 ft-lb/in
Low density Polyethylene (LDPE)
65 – 90℃
Good to excellent
1,200 – 4,000 psi
35,000 – 48,000 psi
Not breakable ft-lb/ in
Polycarbonate (PC)
288 – 316℃
Poor to fail
8,500 psi
13,500 psi
2 – 18 ft-lb/in
Polyoxymethylene (POM)
180 – 230℃
Excellent
6,000 – 22,000 psi
120,000 – 170,000 psi
0.8 – 2 ft-lb/in
Acrylic (PMMA)
130℃
Excellent
2,800 – 10,900 psi
13,000 psi
0.22 – 1.1 ft-lb/in
Thermoplastic Polyurethane (TPU)
71-121℃
Fair to good
6,960 – 12,000 psi
0.8 – 10.1 ft-lb/in
Polypropylene (PP)
65 – 148℃
Excellent
4,500 – 18,500 psi
210,000 – 1,500,000 psi
1.4 – 5.5 ft-lb/in