In two-component injection moulding, two materials with different colours or properties are combined in a single process to create a single component, allowing components with a special appearance or function to be created in a highly economical way.
Basic principles of the 2K injection moulding material combinations
Material compatibility in multi-component injection moulding
The materials should be compatible with each other so that they can form a strong chemical bond with each other. This depends on the specific chemical properties of the plastics used. Some plastics adhere well to each other, while others form a weak bond or are not compatible at all. However, the creation of formfitting bonds can offer a solution.
Thermical properties
The materials should have similar processing temperatures in multi-component injection moulding in order to ensure processability during the injection moulding process. Excessive differences in the melting temperatures can lead to processing problems and reduced component quality during injection moulding.
Mechanical properties
The mechanical properties of the selected materials should correspond to the application purpose of the component. For example, one material could be selected for its stiffness, while the other material is selected for its elasticity or good sliding properties.
Ästhetik und Haptik
Bei Sichtteilen oder Teilen, die mit der Haut in Kontakt kommen, können Materialien speziell aufgrund ihrer optischen Eigenschaften (Farbe, Transparenz) oder ihrer Haptik (weicher Griff, rutschfeste Oberfläche) ausgewählt werden.
Environmental resilience
The materials selected for injection moulding should be able to withstand the environmental conditions to which the component will be exposed. These include UV resistance, resistance to chemicals, water and high temperatures.
Costs and availability
The materials should not only be technically compatible, but also economically viable. Frequently used materialcombinations are generally less expensive and more readily available.
Common materialcombinations in 2K injectionmoulding:
Hard and soft plasticmaterial
Combination of hard plastics such as polypropylene (PP) or acrylnitrile-butadiene-styrene (ABS) with soft thermoplastic elastomers or polyurethanes (TPE, TPU) for handles, seals or soft touch components.
Highstrength and slipcapable synthetic material
One component made of glassfibrereinforced polyamide (PA) and the other component made of polyoxymethylene (POM) offers a combinnation of rigidity and durability with enormous slidingability for plain bearings or similar.
Various coloured art materials from the injection moulding process
Various coloured synthetic materials can be used to set special accents in the product design, for example to highlight logos or functional surfaces.
Wide range of materials for customised solutions
Multi-component injection moulding enables the processing of different material combinations in a single production cycle, resulting in highly functional and customised plastic components. This method is particularly valuable for creating complex parts that combine the physical properties of multiple materials in a single component. A selection of the most commonly used plastics in this advanced manufacturing technique is presented below:
- Polypropylene (PP)
- Polyethylene (PE)
- Polyethylene (PE)
- Polycarbonate (PC)
- Acrylonitrile butadiene styrene (ABS)
- Polyoxymethylene (POM)
- Thermoplastic elastomer (TPE)
- Thermoplastic polyurethane (TPU)
- Styrene block copolymers (TPS)
- Cross-linked thermoplastic elastomers (TPV)
- Polydiorgano - siloxane (silicone)
Below you will find a more detailed explanation of the various plastics that are used in combination in injection moulding.
- Polypropylene (PP): Polypropylene is a thermoplastic known for its excellent chemical resistance, elasticity and electrical insulation. It is often used for packaging, automotive parts and household appliances.
- Polyethylene (PE): PE is characterised by its high toughness, good chemical resistance and flexibility. It is one of the most widely used plastics and is used in bottles, toys and films.
- Polyamide (PA or nylon): Nylon is known for its high strength, abrasion resistance and thermal resistance. It is often used in the automotive industry, in the manufacture of sports equipment and in electrical engineering.
- Acrylonitrile butadiene styrene (ABS): This copolymer is particularly robust and hard, yet easy to process. It is often used for the housings of electrical appliances, toys and other durable items.
- Polyoxymethylene (POM): POM, also known as acetal, offers high strength, rigidity and precise dimensional stability, making it particularly suitable for precision parts in mechanical applications.
- Thermoplastic elastomer (TPE): TPEs are elastic plastics that combine the properties of rubber with the processability of thermoplastics. They are used in seals, flexible hoses and soft-touch components.
- Thermoplastic polyurethane (TPU): TPU is known for its high abrasion resistance, flexibility and oil-resistant proerties. It is used in applications such as shoe soles, hoses and protective covers.
- Styrene block copolymers (TPS): TPS is a group of thermoplastic elastomers characterised by their processability and good thermoplastic properties. Typical applications are soles, seals and toys.
- Cross-linked thermoplastic elastomers (TPV): TPVs combine the properties of vulcanised rubber with the processability of thermoplastics, making them ideal for automotive applications and gaskets.
- Polydiorgano-siloxanes (silicone): Silicone is extremely heat-resistant, flexible and water-repellent, making it ideal for kitchen utensils, medical devices and insulating materials.
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The benefits of collaboration with HECHT + DIEPER
HECHT + DIEPER is your expert in injection moulding of plastics.
Expertise
During development, our customers benefit from our many years of expert knowledge, in the area of design, our own toolmaking, as well as our competence in production.
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