November 29, 2002
A new robotic pressing/fettling system provides fast, precise fettling of even difficult, irregular-shaped items.
Medard de Noblat in Limoges, France, has manufactured porcelain tableware for more than 160 years. For most of the 1990s, the company was still forming its products using traditional bench casting. However, when it secured a large order from Hermes de Paris several years ago, the company realized that it would have to implement a new forming technology to meet the high quality demands of this new customer. While a number of other tableware companies had switched to high-pressure casting due to the technology’s significant quality improvements compared to bench casting, products made through high-pressure casting sometimes deformed after firing. Not wanting to risk this type of defect, the company opted instead for an isostatic pressing system from SAMA Maschinenbau GmbH, headquartered in Germany. The quality of isostatically pressed items is generally better than products produced through high-pressure casting. However, conventional isostatic pressing systems offer limited movement, making it difficult to fettle non-round, multi-sided, rectangular and irregular-shaped products. SAMA’s system has overcome this challenge by incorporating robotic fettling technology that uses specially developed software and six axes to allow customized programming and virtually unrestricted movement of the objects being fettled. The system’s flexibility also ensures that no dust or slip can get in the product during the vertical working stage. In the new system, the isostatically pressed items are placed in a centering device, which feeds the items to the fettling robot. The robot first positions the item in front of a dry grinding device equipped with a grinding belt or disc, then rotates it to a sponging unit with counter-rotating sponge reels. A second sponging unit equipped with a sponge belt or reel handles the final sponging. The robot then replaces the finished item on the centering device and picks up the next item to be fettled. The flexibility of the system ensures that the highest possible edge quality is attained, regardless of the shape or size of the item being fettled. Medard de Noblat installed its first isostatic pressing/robotic fettling system in 1998, and it has also recently commissioned a second system.