euspen’s 17 th International Conference & Exhibition, Hannover, DE, May 2017 www.euspen.eu The Hybrid Machining of Ceramic: The choice of production stage A. Demarbaix 1 , E. Rivière-Lorphèvre 1 , F. Ducobu 1 , E. Filippi 1 , F. Petit 2 1 University of Mons, Faculty of Engineering, Machine Design and Production Engineering Lab, Place du Parc 20, 7000 Mons (Belgium) 2 Research and Technological Support Department BCRC-INISMa (member of EMRA), Av. Gouverneur Cornez 4, 7000 Mons (Belgium) Corresponding author: anthonin.demarbaix@umons.ac.be Abstract The demand for micro products has increased gradually since last decades in various areas, requiring the development of micro manufacturing processes. Micro manufacturing is characterized by the size of functional features (smaller than 10 m), a high precision, a good surface finishing and complex parts in a wide variety of materials. The Traditional Machining Processes (TMPs) are intensively used to produce micro-components, but the minimum feature size they can produce is limited. In parallel, the Nontraditional Machining Processes (NMPs) were developed to manufacture micro components of a few microns, but the processing times are slower. Hybrid Machining Processes (HMPs) was introduced to address the demand to increase production with an enhanced quality for difficult-to-machine materials such as ceramics. In this paper, the HMP considered, a combination of micro-milling and laser machining, is developed to machine ceramic materials. This HMP may be carried out at different stages in the ceramic production. The goal of this paper is to determine the most attractive production stage in ceramic machining with this HMP. Hybrid machining, Micro milling, Laser machining, Ceramic machining 1. Introduction The miniaturization appears as being one of the most important challenges of the last decades. The demand for micro-products requires the development of new micro-manufacturing processes with high performance in the repeatability and the productivity of manufacturing. The Traditional Machining Processes (TMPs) and the Nontraditional Machining processes (NMPs) have been developed to manufacture micro components, but these processes are limited. Consequently, Hybrid Machining Processes (HMPs) have been introduced to get around the limitations [1-3]. The HMP combines a minimum of two machining processes in a single machine centre. In this paper, the two technologies are the micro milling and the laser machining. Actually, these two technologies are complementary because it is possible to combine the high material removal rate of the milling and the precision of the laser machining (See Figure 1). Figure 1. Complimentary of milling and laser machining The studied material is an All-Ceramic material which is a competitive alternative to metal-ceramic materials for manufacturing crowns and fixed partial dentures (FDP). The aesthetical properties and biocompatibility are important advantages in the medical field. Zirconia are ceramics which plays an important role due to their mechanical properties and their biocompatibility (See Table 1). Table 1: Typical mechanical properties of representative dental ceramic materials [4] Ceramic Material Flexural Strength (MPa) Fracture Toughness (√ ) Y-TZP 1200 9.00 Zirconia (3% Y2O3 stabilized) 900 9.00 Alumina industrial 547 3.55 Alumina slip cast 419 2.48 Y-TZP properties are the result of the mechanism of transformation toughening. Indeed, quadratic lattices substitute monoclinic lattices at ambient temperature. The transformation from tetragonal phase to monoclinic phase achieves during energy input, such as the crack. (Energy input like a crack allows transformation from tetragonal to monoclinic phase.) The monoclinic phase is thermodynamically stable in the stress field around the crack. The stress-induced transformation of metastable tetragonal zirconia particles generates a compressive stress around any crack. The mechanism causes the spread of these cracks to be hampered [4,5]. 2. Methodology The HMP may be carried out at different stages in the ceramic production (See Figure 2). The different production stages can be used in the ceramic machining. For each technology of the HMP, each production stage is investigated, by experiments or by a literature analysis to select the most appropriate choice.