Rapid Shell Moulding ( RSM ) - Its Use in Producion of Hearing Aids

Topics Covered

Background

In-The-Ear Hearing Aids – Custom Devices

The Rapid Shell Modelling Process

The Rapid Shell Modelling User Interface

Summary

Background

Materialise, a leading company in computer-aided design software, and top hearing aid manufacturers Phonak and Siemens came together to improve the overall manufacturing processes of hearing aids. Materialise collaborated closely with both companies to develop the automated rapid shell modelling (RSM) application. The goal was to improve efficiency and reproducibility in hearing aid design and manufacture. With the return rates on hearing aids currently running at up to 25%, reproducibility and improved quality were important objectives.

In-The-Ear Hearing Aids – Custom Devices

‘In-the-ear hearing aids are custom manufactured products that must match the anatomy of the patient’s ear canal exactly,’ said Christoph Widmer of Phonak. ‘Their production is a very labour-intensive process, with little scope for automation or information technology. As a result, it’s not easy to reproduce a hearing aid that’s become defective or been lost. Rapid shell modelling changes this by integrating advanced design automation and rapid prototyping technology into a single process. We can now manufacture hearing aids directly from output produced by the rapid shell modelling application.’

The Rapid Shell Modelling Process

In the rapid shell modelling process, a three-dimensional model of the patient’s ear canal is computed from the scanned impression of the ear canal. This model can be further manipulated by using RSM’s sophisticated geometrical algorithms to obtain the finished hearing aid shell. A single shell can be produced in 3-6 minutes, and both the left and right hearing aids are produced simultaneously. The geometry of each hearing aid is archived, which makes it easy to reproduce an identical copy when the hearing aid is lost or damaged.

The Rapid Shell Modelling User Interface

The rapid shell modelling application was developed with an advanced user interface. The operator is taken through each step of the shell manufacturing process in a structured sequence closely resembling the manual process. The software also allows the user to ‘virtually’ assemble the hearing aid on screen, while the application verifies that all the components will fit into the instrument.

Summary

‘We are very pleased with the result,’ said Bart Swaelens, Manager of Materialise’s software division. ‘Our extensive experience in design automation and rapid prototyping aided Phonak and Siemens in accomplishing their goal. The project is now over a year old and first versions of the software have been in use for several months. The results show that we have definitely reached our goal.’

Source: Materials World, Vol. 11, no. 2, p. 8 February 2003.

For more information on this source please visit The Institute of Materials, Minerals and Mining.