Multi-component injection moulding
Multi-component injection moulding brings together several colours or materials in a single mould to improve the design and function of plastic parts. Find out here how multi-component parts can be produced in a single step without joining technology or subsequent assembly and how the injection moulding process and robotic systems can be managed centrally in turnkey systems using the SELOGICA control system.
More space, modularity and convenience in multi-component injection moulding
ARBURG is launching a new series for efficient multi-component injection moulding: the ALLROUNDER MORE machines, which are particularly flexible in their configuration, can be adapted even better to the respective requirements. They offer increased space for larger moulds, more modularity in assembly, as well as numerous optimised features for greater ease of use and simple maintenance.
The new machine can be configured to be either an electric or a hybrid model, and offers numerous optimised features for two-component injection moulding. A current example is the manufacturing of toothbrushes in hard/soft combination. The increased installation space offers more room for larger moulds and convenient mould changes. For the design of the ALLROUNDER MORE, high priority was placed on ease of maintenance. For this reason, the material feed is positioned outside the mould area and the vertical injection unit can be changed quickly using plug-in media connections.
Hard-soft combinations with an attractive tactile surface
A production cell built around a hydraulic ALLROUNDER 570 S uses a 1+1-cavity mould to produce handles for Gardena garden saws from 40% glass fibre-reinforced PP and soft-touch TPE (25% glass fibre-reinforced) in a cycle time of around 35 s.
The injection moulding machine is equipped with a compact robotic cell: an AGILUS six-axis robot, which moves on an additional linear axis transversely to the machine, is positioned above the moving platen. It removes the handles, transports them to a pad printing station and camera inspection and then sets them down on a conveyor belt. The robotic cell is easy to program thanks to the implemented SELOGICA user interface and, like the mould functions, is integrated in the machine control system.
2-component closure: simultaneous filling, cooling and removal
An innovative cube mould is used for the production of two-component water bottle closures. ARBURG fully integrates mould functions such as servo-electric turning into the multi-component ALLROUNDER 920 S injection moulding machine.
A 32-cavity cube mould from Foboha is used to produce closure caps for five-gallon water bottles. The cycle time is around 10 seconds, while the material throughput is over 120 kilograms per hour. Thanks to the four mould sides that can be used during production, the mould filling, cooling phase and part demoulding can be carried out simultaneously. Compared to conventional moulds, the system enables many more cavities to be implemented on the same mould mounting surface. This ensures a correspondingly higher production performance and significantly shorter cycle times.
Functional part in a single step
The cost-effective manufacture of functional components in a single step is a domain of plastics processing. Thumb wheels for passenger car interiors are a good example: Thanks to a targeted combination of materials, high-quality plastic parts with a soft-touch surface are produced.
The thumb wheels can be produced in a fully automatic process sequence on a hydraulic three-component ALLROUNDER 570 S injection moulding machine. This enables efficient high-volume production of these sophisticated functional components. Initially, the translucent main body is produced from PC, then an electroplateable visible surface is added in ABS before a third, attractively tactile TPE component is injected.
Thick-walled optical components
The so-called overmoulding process is suitable for producing high-quality thick-walled lenses in several layers – with shorter cycle times. An automated two-component machine with six-axis robotic system is used.
It makes no difference here whether a lens has been produced in several operations or in only one, component quality is equally high in both cases. Nonetheless, an optical component produced in two stages requires much less cooling time. In the example shown, an electric ALLROUNDER 520 A with a clamping force of 1,500 kN and a 4+4-cavity mould operates with three stations. The six-axis robotic system removes the finished lenses from the open third station and transfers them to an optical testing station. The cycle time for every four PMMA lenses is only approx. 40 s.
Complex electronic component
Three into one: A magnetic disc, carrier plate and protective cap are moulded into a functional rotary encoder using the three-component process. The innovative mould concept and the complex automation solution dispense with joining techniques and downstream assembly.
All operations are combined in a single process – including insertion of the sensor and overmoulding with a carrier plate as well as magnetisation and assembly injection moulding directly in the mould. A fully automated production cell built around a hydraulic ALLROUNDER 370 S injection moulding machine featuring three (size 30, 70 and 30) injection units.
to the moulded part
Combined thermoplastic and LSR processing
For the production of a dishwasher keypad, thermoplastic and silicone are processed on an electric ALLDRIVE series injection moulding machine to form a hard-soft combination. Here, various material properties can be brought together in a targeted manner and a single production step.
A particular challenge is the joint processing of “hot” and “cold” materials in a single cycle and one mould: the PA must be cooled, while the LSR cross-links at a high temperature. The relevant sections in the mould are consequently separated from one another by means of thermal insulation. This is why transfer technology is particularly suitable here. The moulded parts are transferred in the mould via a MULTILIFT robotic system.