Titanium housing created using a 3D printer
Creating a number of prototypes showed us that to achieve the vast, true-to-life sound stage we aspired to,
the housing needed to meet the following conditions:
・ A mechanical equalizer on the front surface of the diaphragm
・ The back of the driver unit being open to a large degree
・ A space between the housing and the user's auditory canal was necessary
When we conducted simulations regarding the optimal form for the mechanical equalizer based on the points above gleaned through the prototypes, we realized that such a form could only be achieved using a 3D printer. To create a complicated metal form using a 3D printer, however, required a great deal of knowledge and know-how regarding molding. The image of this thing called a printer is that the 3D data sent to it is created with the press of a button, but this is not actually true. With a 3D metal layering printer, a level layer of 30μ metal powder is irradiated using a laser and fused together to create a form. Metal powder is layered onto this with a high degree of accuracy; the same process is repeated over a long period of time to create a shape. Because of this, changes to the form owing to the heat created during the molding process need to be considered, or a high level of precision will not be possible. It is necessary to redraw the 3D data drawn up by the designer into data and a form for molding. There is no set way of doing this; it is necessary to create a test piece and take this data into account to determine a form.
Here, with the cooperation of NTT Data Engineering Systems (NDES), we were able to create a mechanical equalizer whose thinnest section was just 0.2mm. NDES engineers took into consideration all of the conditions necessary in terms of sound quality together with those necessary for high-precision molding – including heat radiation - and derived the most appropriate form for the mesh covering the surface.
The mesh form on the outer surface is not just for the sake of sound quality;
it is also a form that heightens molding precision.
In order to derive the most appropriate form, engineers from NDES and from our own company shared their ideas, shaping and modeling over and over. A lot of know-how very difficult to put into words was necessary during this process. It is said that if you have a 3D printer, you don't need artisan skills. In actual fact, shaping something using a 3D metal layering printer becomes possible only when you have an engineer known as a "3D shaping artisan". The reason you don't find products around you that have been molded using a 3D metal layering printer is because molding using such a printer is a mass of detailed know-how.