The digital sculptor

from Sara Bertsche | Nov 17, 2014

Sure, curving organic lines and a soft silhouette look just wonderful but are difficult to produce. Let’s take a classic, Finn Juhl’s No. 45 Chair, created by the legendary Danish designer in 1945. Onecollection recently began to mass produce it. The chair stands out for its delicate lines and the fact that seat area and backrest are separate from the frame. This made it decidedly complicated to manufacture, which is why for a long time the chair was reserved for a small, select circle of design lovers – a conscious decision by the designer. It is thanks to CNC milling that it is now experiencing a revival – and in larger quantities.

Italian manufacturer Mattiazzi is likewise known for its flowing, three-dimensionally shaped furniture items. And in Udine, too, CNC machines do magic, enabling really special furniture such as Ronan and Erwan Bouroullec’s “Osso” stool whose legs apparently merge seamlessly into the three-dimensional seat area.

Similarly, manufacturers such as ClassiCon, Ceccotti Collezioni and Emmemobili use digitally controlled milling machines to realize asymmetrical forms and precise edges measuring just a few millimeters.

Digital precision tool

Fast, efficient and right to the millimeter – the digitalization of manufacturing processes has occasioned a fundamental change in industrial production. The furniture industry employs tools controlled by computer data to shape materials like wood, metal and plastic. Milling by Computerized Numerical Control, or CNC, is a subtractive manufacturing method, meaning that material is removed from the material block until the desired shape emerges. The work that a sculptor or skilled carpenter completed intuitively is now done by machines in a single process: Furniture is made “in a single step”.

The re-edition of Finn Juhl’s No. 45 Chair demonstrates that the design need not be new in order to benefit from the use of digitally controlled machines. While the manufacture of such furniture used to be highly complicated and required a large number of steps that had to be performed by hand, now the production process can be significantly shortened and made more cost-effective.

Complicated manual operation

With the preceding models, the NC milling machines, which were first employed in Europe in the 1960s, the machine operator had to demonstrate a high degree of concentration, as a lot still had to be done by hand. First, he had to make calculations based on drawings and item lists in order to determine the position of the tools. Subsequently, he had to align the heavy tool slides through handwheels. And he also had to perform the final inspection. Lengths, widths, heights and angles had to be checked right to the millimeter. If the finished items failed their inspection, perhaps owing to a calculation error, the pieces had to be corrected. Moreover, as the milling tool always moved in one direction, the material block had to be permanently inserted differently. For a complicated shape, for example one with an especially small concentricity, this meant having to resort to traditional methods using a plane iron and grinding tools. It is easy to imagine how difficult it was to produce a chair whose sections had different curves, torsions, and shapes.

Fast and efficient

CNC milling machines are faster, more efficient and more precise because they are controlled by a digital code. First, a CNC program encodes all the measurements from a CAD drawing of the tool and uses this information to calculate the work steps for the machines. the choice of tool and its exact positioning above the material block is likewise automatic. Moreover, thanks to a special changing system tools can be automatically replaced during a milling operation. All the machine operator needs to do is to insert the workpiece and determine the reference points for processing. There are no calculation errors, there is no tiring winding to be done. CNC-milling machines can have up to fifteen axes, which enables the manufacture of three-dimensional shapes in a single step. Alas, there is a minor drawback. If there’s an error in the program then the workpiece will be faulty and material is wasted. After all, the machine operates too quickly for it to be stopped in time. So the CNC milling machine in not one-hundred percent perfect.

In the end it’s the design that counts

A CNC milling machine is a digital precision tool that permits workpieces with complex forms to be mass produced. As items can be produced so quickly and efficiently this opens up a huge bandwidth of variations, as it is possible at any time to modify the model based on digital data and which forms the starting point for milling operation. And even though mass production may mean that Finn Juhl’s gem will lose its prestige value as a rare item of furniture manufactured in small numbers the design itself still remains valuable. After all, good design remains good design.
Seamless transition: With the CNC milling machine the soft curves of “Osso” can be realized. Photo © Mattiazzi
With its curved and seamless lines, the wardrobe ”Saturn” by Edward Barber and Jay Osgerby looks very slightly.
Photo © ClassiCon