Martina Methner examines how e-Manufacturing is especially suited for the direct manufacture of end-use parts in plastics and metal.

Laser-sintering is a generative manufacturing method which creates solid parts by locally solidifying powder materials using a scanning laser beam. Over the past 10 years, laser-sintering has developed from being a leading method for rapid prototyping and rapid tooling to become the key technology for e-Manufacturing.

e-Manufacturing becomes a viable solution in industries where the following market characteristics dominate:

• Forecast predictability is low.
• There is a strong need for customised products which results in a high number of product variants.
• As a consequence, batch sizes are relatively small.

Furthermore, e-Manufacturing offers new opportunities in industries with the following product characteristics:

• Products have a relatively small size and are very complex (either in function or geometry).
• Lead-times are short.

An example demonstrating the benefits of e-Manufacturing for plastic parts is the application of Model Shop Vienna. The Austrian company uses laser-sintering technology to manufacture handset holders for a public phone (Fig. 1).

Initial order

Model Shop Vienna received an order of Telekom Austria to provide a total of almost 1000 of the holders over a period of one year. The initial order, however, was only given for 250 of the holders with the remaining 750 holders as an option.

In this situation e-Manufacturing with Alumide, an aluminium-filled polyamide, was the method of choice. On the one hand this material combines all the properties the customer demanded with regards to metallic appearance and high stiffness. On the other hand laser-sintering allowed Model Shop Vienna to react flexibly to unpredictable design changes the customer might want to add in follow-up orders.

Laser-sintering results in a linear cost curve. Thus, Model Shop Vienna did not have to bear the risk of placing a certain amount of orders of identical parts to reach the break-even-point where the heavy investments in tooling would pay off.

Any follow-up order can be carried out at the same costs as the initial one. This holds true even if design changes become necessary or if smaller lot sizes are required. Eliminating the risk of sunk costs in tooling equipment made e-Manufacturing an appealing option.

Mass customisation

An industry with a particular strong need to customise their products is the hearing aid industry. Since the success of hearing aids very much depends on its ability to adapt to the anatomy of the auditory canal, this industry can not offer any mass manufactured product. Fig. 3 illustrates a fully equipped hearing-aid with a laser-sintered shell.

The process of producing hearing aids with e-Manufacturing is as following:

• Take a copy of the auditory canal anatomy by creating a wax cast.
• Scan the wax cast with a scanner to create 3D data.
• Integrate an identification number in the 3D data that helps to identify the hearing aid shell after the laser-sintering process.
• Laser-sinter the shell.
• Combine the laser-sintered shell with the electronics components.

In the hearing aid industry laser-sintering has become the manufacturing method of choice. The manufacturing process runs at the same efficiency, no matter whether a certain number of identical or individual products (one-offs) are produced. The build envelope of a laser-sintering system can be filled with several hundred of hearing aid shells – hundreds of products can thus be produced over night. In this case e-Manufacturing unleashes its full potential: the ability to directly run a manufacturing process from 3D CAD data is crucial in the case where no two parts are the same. In the later stages of the product life cycle the data can be re-used in order to provide spare parts with the identical geometry as the original part. Apart from the geometry every part can be distinguished by a serial number at the inside of the shell serving as patient identification code.

At the current state of laser-sintering technology a yearly output of 100 000 hearing aid shells can be achieved with one single plastic laser-sintering machine.

The examples are just two out many. But they show that e Manufacturing is already being used successfully for production of end-use parts in different applications. It is to be expected that the number and range of suitable applications will continue to expand.

Enquiry details

Martina Methner is with EOS Gmbh – Electro Optical Systems, Krailling, Munich, Germany. www.eos.info