CoCr Is Not the Same: CoCr-Blanks for Dental Machining

Abstract

Modern computer-aided technologies for manufacturing of individual prostheses are gaining popularity in the dental technology. The CAD/CAM technology promises a material-oriented processing of the manufactured material blanks. Especially with the cast processing of metals to master the process is essential. The control of the casting process directly affects the material quality and thus the clinical chances of success. Possible errors in the casting process, such as gas cavities, scabs, bubbles and cast stresses lead to a significant deterioration in the quality of the material. With the industrial production of material in blank form and their industrial machining this problem should be avoided. But it was the machining of difficult to machine materials such as cobalt-chromium alloys which presents new challenges.

Due to the increasing cost pressures in the manufacturing of dentures, the milling technology users are forced to reduce milling time and extend tool life. To achieve this, the Institute of Manufacturing Technology and Quality Management of the University of Magdeburg made investigations for a possible optimal machining process. As a first step, mainly in the German market used cobalt-chromium alloys have been analyzed by a crystal structure and EDX analysis as well by a macro-and micro-hardness measurements. Aim is to identify the impact of tools, width and depth of cut, cutting speeds and the used cobalt-chromium alloy on both the manufacturing and the material quality after processing. The investigation raises fundamental questions for process safety, the material removal rate and the tool wear. Machining tests were carried out to determine the impact of different material compositions and how these affect the milling process.