Material selection for injection moulding is crucial for a product's success. However, in practice, this choice is often made too late, only after the design has already been finalised. This leads to problems: a material that doesn't fill as expected, shrinks upon cooling, or fails to meet mechanical requirements. The right plastic should be chosen based on function, environment, and processing properties, not solely on habit or price.
Thermoplastic materials as a basis for injection moulding
Injection moulding as a production technique It exclusively processes thermoplastic plastics. These are materials that become liquid when heated and harden when cooled without chemical change. This makes the process reproducible and suitable for large series.
The best-known thermoplastic materials are PP, PE, ABS, PA, POM, and PC. Each has its own profile of rigidity, impact resistance, chemical resistance, and thermal load capacity. These properties determine in which application a material functions and what processing parameters are required.
Thermosetting plastics such as epoxy or polyurethane are not suitable for conventional injection moulding. These cure through a chemical reaction and cannot be remelted. At Eurotechniek, we exclusively work with thermoplastic materials, tailored to the customer's technical and production requirements.
Standard materials for general use
PP and ABS are the most commonly used materials in industrial series production. PP is lightweight, chemically resistant, and easy to process. It has a low density, good fatigue resistance, and is resistant to most acids and bases. PP is well-suited for housings, clips, pipe components, and consumer goods.
ABS combines rigidity with impact resistance and adheres well to paints and coatings. It is easy to machine after injection moulding and lends itself well to surface finishing. ABS is widely used in electronics housings, automotive applications and engineering components that require an attractive appearance.
PC, or polycarbonate, offers high transparency and excellent impact resistance. For applications requiring optical properties or protection against impact, PC is a logical choice. One example is a transparent cover for a measuring instrument that needs to be both scratch-resistant and optically clear.
Technical plastics for heavier loads
As environmental conditions become more challenging, standard materials are no longer sufficient. Higher temperatures, mechanical stress, or aggressive media require technical plastics with a more specific property profile.
PA, polyamide, is one of the most widely used engineering plastics in the manufacturing industry. PA6 and PA66 are standard, but glass fibre reinforced variants such as PA66 GF30 have significantly higher stiffness and temperature resistance. They are used in gears, housings for electric motors, and structural components in the automotive sector.
POM, polyacetal, has high rigidity, low friction and excellent wear resistance. It is the standard choice for sliding components, precision gears and bearing seats. POM is relatively easy to process using injection moulding, but requires precise temperature control to prevent degradation. Eurotechniek regularly processes POM into precision components for mechanical engineering clients.
High-quality materials for extreme conditions
For high-temperature applications, contact with aggressive chemicals, or in the medical sector, high-performance engineering plastics are essential. PEEK, PPS, and PSU are materials that perform structurally where standard and engineering plastics fail.
PEEK can withstand temperatures of up to 250 degrees Celsius and has excellent mechanical properties right up to that limit. It is biocompatible and is used in medical implants, aerospace components and semiconductor manufacturing. Processing temperatures are high, and the mould must be kept at the correct temperature to control shrinkage and internal stresses.
PPS, polyphenylene sulfide, is chemically extremely resistant and self-extinguishing. It is used in pump housings, automotive industry connectors, and parts that come into direct contact with fuels or lubricants. PPS shrinks very little during injection moulding, making it suitable for precise parts with tight tolerances.
Reinforced and filled variants
Base polymers are often reinforced with glass fibre, carbon fibre, or mineral fillers to improve specific properties. Glass fibre reinforcement increases stiffness and lowers thermal expansion. Carbon fibre reinforcement adds high stiffness and low weight, but demands more from the tooling due to its abrasive properties.
Mineral fillers such as talc improve surface quality and stiffness at low cost. They are widely used in PP compound series for automotive interior parts. The choice of filler and the filling percentage directly influence the processability, shrinkage, and mechanical properties of the final product.
A practical example: a structural bracket that was previously manufactured from aluminium was converted to PA66 GF30. The result was comparable stiffness with a 20 per cent weight saving and a lower unit cost in series production. Eurotechniek supports this type of material substitution from the initial calculation right through to validated series production.
Material processing and mould design are related.
Choosing the right plastic is one step. The mould must be designed according to the properties of that material. Each plastic has its own shrinkage value, flow characteristic, and temperature window. A mould for PP will not work without modifications for POM or PEEK.
Shrinkage is one of the most critical parameters. PP has a shrinkage of 1.5 to 2 percent. POM is at 2 to 2.5 percent. PEEK shrinks considerably less but is more sensitive to process variations. The mould maker must factor these values into the cavity dimensions to keep the final product within tolerance.
Gate locations, cooling channel geometry and draft angles all depend on the chosen material. Eurotechniek designs the mould and selects the material in conjunction with one another. This prevents the need for rounds of corrections following the initial T1 samples and shortens the validation process.
Frequently asked questions about plastics for injection moulding
Can I have any thermoplastic material injection moulded?
In principle, an injection moulding machine can process any thermoplastic polymer, but the reality is more nuanced. Materials such as PEEK or PPS require higher processing temperatures and specialised moulds that are kept at the correct temperature. Not every injection moulding company has the right equipment and expertise for these materials. Eurotechniek processes a wide range of thermoplastic materials and assesses, on a case-by-case basis, whether the material is suitable for the available production capacity and the required quality.
How do I choose the right material if I don't yet precisely know the technical requirements?
Start with the environmental conditions: temperature, media, mechanical load, and any standards such as fire safety or medical certification. From these requirements, you can draw up a shortlist of suitable materials. Eurotechniek actively provides input on this. We assess the design, the application, and the production volumes, and provide a targeted material recommendation with justification. This way, you won't face any surprises after the first production run.
Does the choice of material affect the mould costs?
Yes, directly. Materials with high processing temperatures or abrasive fillers place higher demands on the mould steel. For glass fibre or carbon fibre reinforced materials, hardened tool steel is necessary to prevent premature wear. This increases the initial mould investment. At the same time, the choice of material determines the cycle time, scrap rate, and quality assurance, all of which affect the total production costs. A good material choice early in the process saves more than it costs.
Material selection makes or breaks an injection moulding project
The wrong plastic can lead to dimensional inaccuracies, breakage during use or a mould that fails to deliver what was promised. The right choice of material, combined with good mould design, is the basis for reliable series production.
Would you like to know which material is suitable for your application and production volume? Contact Eurotechniek via euro-techniek.nl. We will assess your design and provide a concrete material recommendation, without detours.