With over 85,000 commercial plastic material option available and 45 polymer families, there is a wealth of different plastics that can be used for injection moulding. Of these, the polymers can be broadly placed into two groups; thermosets and thermoplastics.
The most common types of plastic used are high-density polyethylene (HDPE) and low-density polyethylene (LDPE). Polyethylene offers a number of advantages including high ductility levels, good tensile strength, strong impact resistance, resistance to moisture absorption, and recyclability.
Other commonly used injection moulded plastics include:
This tough, impact-resistant plastic is widely used across industry. With good resistance to acids and bases, ABS also offers low shrinkage rates and high dimensional stability.
This strong, impact resistant plastic has low shrinkage and good dimensional stability. A transparent plastic that is available in different optically clear grades, PC can provide a high cosmetic finish and good heat resistance.
There are many different types of PPA (or nylons), each of which has its own advantages. Generally-speaking, nylons offer high strength and temperature resistance as well as being chemically resistant, apart from against strong acids and bases. Some nylons are abrasion resistant and offer good hardness and stiffness with good impact strength.
Commonly known as acetal, this plastic has high hardness, stiffness, strength and toughness. It also has good lubricity and is resistant to hydrocarbons and organic solvents. Good elasticity and slipperiness also provide advantages for some applications.
PMMA, also known as acrylic, provides good optical properties, high gloss and scratch resistance. It also offers low shrinkage and less sink for geometries with thin and think sections.
This inexpensive resin material delivers high impact resistance in certain grades but can be brittle in cold temperatures (in the case of propylene homopolymer). Copolymers offer greater resistance to impact while PP is also wear-resistant, flexible and can provide very high elongation, as well as being resistant to acids and bases.
Good electrical properties makes PBT ideal for power components as well as automotive applications. The strength ranges from moderate to high depending on glass fill, with unfilled grades being tough and flexible. PBT also shows fuels, oils, fats and many solvents, and it also doesn’t absorb flavours.
8. Polyphenylsulfone (PPSU)
A dimensionally stable material with high toughness, temperature and heat resistance, PPSU is also resistant to radiation sterilisation, alkalis and weak acids.
This high temperature, high-performance resin provides heat resistance and flame retardancy, excellent strength and dimensional stability, as well as good chemical resistance.
PEI (or Ultem) offers high temperature resistance and flame retardancy, along with excellent strength, dimensional stability and chemical resistance.