cross dimensional manufacturing

A world full of sound

Bringing the smallest of parts into full-size view

Sonova, headquartered in Stäfa, Switzerland, is the leading provider of innovative hearing care solutions. The company pursues the simple vision of creating a world in which there is a solution for every type of hearing loss and all people equally enjoy the delight of hearing. Sonova uses a complete solution from toolcraft to manufacture and package a cerumen filter protection device for hearing aids. Experts from injection moulding, mould making and robotics work together closely to produce the complete dispenser system, which includes eight filters. The dispenser system comprises three external parts (bottom, top and label), with the filters inserted into the bottom. There is also a mass storage unit housing additional filters so that the hearing aids can be fitted with an initial filter on Sonova’s assembly line.

Used technologies:


Sonova Holding AG

The starting point:
Design follows process

The filter can be changed by the hearing aid wearer independently. This increases the durability of the hearing aid, improves its performance and makes it easier to use. The initial design of the cerumen filters and the dispenser system had to be revised in close cooperation with the client in terms of its manufacturing feasibility and ability to be produced automatically. Besides the fully automated production process, discussions focused on economic efficiency. During the design and construction of the systems, particular attention was paid to the high accuracy and precision of the individual components. The actual filter is smaller than a granule and is produced using micro-injection moulding. Its intricate design gives the product a longer lifecycle.

the challenge:
Bringing the smallest of parts into full-size view

Ensuring it was possible to manufacture the tool and to handle the filters during production proved to be the greatest challenge. This is where toolcraft’s longstanding experience and expertise in design, mould making for very small parts, robotics and injection moulding came in. The development of an automated process was particularly tricky when determining how the parts could be picked up and handled. Inspecting the parts using a camera and laser micrometer technology as well as lasering the packaging components in the predetermined cycle time demanded extensive knowledge of process development and camera and laser technology. The delivery time was also very tight and changes to the materials during the project put the team under additional pressure. Various materials were ultimately selected. The bottom is made from SAN, the top and the mass storage packaging from ABS, and the label from PS. During the filter manufacturing stage, the material was changed to POM with fibreglass. This posed additional challenges during the removal of the parts from the mould as well as when connecting the parts, handling them using robots, separating and inspecting them.

the approach:
Perfekt kombiniert

  • Compilation of a project team comprising specialists in mould making, robotics and injection moulding
  • Feasibility study examining the plastic components in terms of tools, injection moulding, gripping technology and separation during the automation process
  • Coordination of the design with the client and optimisation of the geometry
  • Conceptual development of processes for manufacturing, removing and handling the components and for conducting simulations using VR glasses
  • Tool design and simultaneous construction of the automation system
  • Bringing together the individual components and start-up    
  • Simultaneous construction of a second assembly line
  • Continuous quality assurance via random CT measurements

the results
A world full of sound

A number of challenges had to be overcome due to the fact that the deadline for starting production of the new generation of hearing aids had already been set in stone and due to changes in the materials and design during the project. The project team worked with the client to overcome these brilliantly. The tight time constraints also meant that the second system had to be planned and put into series production at the same time as the first. Thanks to its excellent network of suppliers and the expansion of its own expertise in automated injection moulding, toolcraft successfully completed a project in a class of its own. The filter systems have been rolling off the fully automated production line ever since and are used in the new hearing aids to ensure wearers can enjoy a world full of sound.

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Thomas Lender

Business Unit Manager Injection Moulding

Andreas Bauer

Business Unit Manager Robotics

Daniel Distler

Business Unit Manager Robotics

Anton Meixner

Business Unit Manager Mould Making