Laser Sintering Process Analysis: Application to Chromium-Cobalt Alloys for Dental Prosthesis Production

Abstract

Rapid prototyping is an effective way to build prototypes. This process, now called AM (Additive Manufacturing), is suited to realize functional single part or for small batch production. Evolution of AM is now in the way of serial production. In the field of medical applications and more precisely dentistry, AM is a way of increasing numbers of elements produced compared to classic production by lost wax casting. To increase production quality, it is necessary to have a high monitoring and control of process and properties of production. In the case of AM using (DMLS: Direct Metal Laser Sintering), a lot of parameters can have an influence on the elements production quality such as powders quality, laser behavior or sintering time… The goal of this work is to study the serial production quality using a DMLS system (Phenix System PM100). This system is used in production of cobalt-chromium elements for dental applications. The study was done on a period of 6 months with recording results of almost 120 productions and was focused on a quantity of around 7000 dental elements produced. In a first part, number of elements per production, room temperature and hygrometry, powder reloading, maintenance, production stops and new operators are recorded. Material properties of some elements produced such as dimensional properties, density, porosity and crystallographic phases are monitored. Materials analysis has led to ensure the elements quality produced by the Phenix system and results are discussed in this work. In a second part, we focused on the production analysis with the recorded data. Analysis leads to define 2 ratios: production ratio RP defined as [Elements Number]/ [Productions Number] and the efficiency production PE defined as the ratio RP/[Stopped production number]. By calculating RP and PE values with collected data on the Phenix system, a PM 100 efficiency production modeling has been established. The PM 100 production modeling can help to understand that increasing the production ratio RP value leads to have efficiency production PE high variation. On another hand, collecting production parameters leads to increase production efficiency.

Review of selective laser melting: Materials and applications

“…Cobalt-chrome has been studied by various groups for dental applications. Faure et al 146 recorded results of 7000 dental elements produced over a span of 6 months. Averyanova et al 147 studied the fabrication of 99% dense Co-Cr dental crown and bridges over a period of 14 months and concluded that SLM has good repeatability and these parts made by SLM meet the traditions standards.…”

Additive Manufacturing of Cobalt‐Based Dental Alloys: Analysis of Microstructure and Physicomechanical Properties

“…Given that the criterion applied in the aeronautics industry for Advances in Materials Science and Engineering RD is greater than 99%, these values could be considered to be exceptional for the manufacturing process [27]. For most applications, such a high RD is not required and a correlated reduction in mechanical strength is traded for speed and economic fabrication [28][29][30]. However, for dental metallic devices, the RD is also relevant to accomplish a tissue-friendly, void-free satin finish, which is achieved via electrolytic polishing to prevent fitting and cleaning problems on the fitting surface of denture frameworks.…”

Additive Manufacturing of Cobalt-Based Dental Alloys: Analysis of Microstructure and Physico-Mechanical Properties

“…Given that the high quality criterion applied in the aeronautics industry is RD greater than 99%, these values could be considered to be exceptional for the manufacturing process [27]. For most applications, such a high RD is not required and a correlated reduction in mechanical strength is traded for speed and economic fabrication [28][29][30]. However, for dental metallic devices, the RD is also relevant to accomplish a tissue-friendly, void-free, satin finish, which is achieved via electrolytic polishing to prevent fitting, and cleaning problems on the fitting surface of denture frameworks.…”