scholarly journals An Experimental Study on Micro-Milling of a Medical Grade Co-Cr-Mo Alloy Produced by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2208 ◽  
Author(s):  
Gabriele Allegri ◽  
Alessandro Colpani ◽  
Paola Serena Ginestra ◽  
Aldo Attanasio
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Chip Thickness ◽  
Material Behavior ◽  
Micro Milling ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
Chip Formation Mechanism ◽  
Manufacturing Techniques ◽  
Cobalt Chromium Molybdenum

Cobalt-chromium-molybdenum (Co-Cr-Mo) alloys are very promising materials, in particular, in the biomedical field where their unique properties of biocompatibility and wear resistance can be exploited for surgery applications, prostheses, and many other medical devices. While Additive Manufacturing is a key technology in this field, micro-milling can be used for the creation of micro-scale details on the printed parts, not obtainable with Additive Manufacturing techniques. In particular, there is a lack of scientific research in the field of the fundamental material removal mechanisms involving micro-milling of Co-Cr-Mo alloys. Therefore, this paper presents a micro-milling characterization of Co-Cr-Mo samples produced by Additive Manufacturing with the Selective Laser Melting (SLM) technique. In particular, microchannels with different depths were made in order to evaluate the material behavior, including the chip formation mechanism, in micro-milling. In addition, the resulting surface roughness (Ra and Sa) and hardness were analyzed. Finally, the cutting forces were acquired and analyzed in order to ascertain the minimum uncut chip thickness for the material. The results of the characterization studies can be used as a basis for the identification of a machining window for micro-milling of biomedical grade cobalt-chromium-molybdenum (Co-Cr-Mo) alloys.

Development of 3D Finite Element Model for Predicting Process-Induced Defects in Additive Manufacturing by Selective Laser Melting (SLM)

2016 ◽  
Author(s):  
Bilal Hussain ◽  
A. Sherif El-Gizawy
Keyword(s):  
Additive Manufacturing ◽  
Laser Beam ◽  
Selective Laser Melting ◽  
Thermal Stresses ◽  
Cost Effective ◽  
Element Model ◽  
Laser Melting ◽  
Two Phase ◽  
Free Process ◽  
Manufacturing Techniques

Selective Laser Melting (SLM) is one of the important Additive Manufacturing techniques for building functional products. Nevertheless, the absence of accurate models for predicting the SLM process behavior, delays development of cost effective and defects free process. This work presents a coupled thermo-mechanical numerical model to capture the two phase (solid-liquid) solidification melting phenomena that occur in the process. The proposed model will also predict the evolvement of process-induced properties and defects particularly residual stresses caused by temperature gradient and thermal stresses. CO2 or Nd:YAG laser beam can be used as a heat source with a Gaussian distribution for the laser beam energy.

Surface Formation Mechanisms in Selective Laser Melting of Cobalt-Chromium-Molybdenum Powder

2020 ◽  
Vol 839 ◽  
pp. 73-78
Author(s):  
Alexander A. Saprykin ◽  
Yuriy P. Sharkeev ◽  
Natalya A. Saprykina ◽  
Egor A. Ibragimov
Keyword(s):  
Selective Laser Melting ◽  
Marangoni Effect ◽  
Powdered Material ◽  
Formation Mechanisms ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
Movement Velocity ◽  
Surface Formation ◽  
Preheating Temperature ◽  
Cobalt Chromium Molybdenum

Selective laser melting (SLM) is a manufacturing technology of metal parts of any shapes with target mechanical properties by means of laser melting. This paper discusses the effect of SLM parameters: laser output power, laser movement velocity, scanning pitch and preheating temperature of a powdered material on surface formation mechanism, namely, its physical configuration when melting cobalt-chromium-molybdenum powdered material Со28Cr3Mo. The study points at structural differences of melted surfaces even under identical process parameters. Several types of surface formation are identified, e.g. homogenous melt, coagulated particles, and shapeless particles. Vapor pressure, Marangoni effect, and heat effect of a melted powder are stated to be key reasons for rough surface. This research is of high importance for understanding the effect of SLM parameters on formation of a target quality surface, positive stability and repeatable accuracy of the process.

Properties of Aluminium Alloys Produced by Selective Laser Melting

2016 ◽  
Vol 710 ◽  
pp. 83-88 ◽  
Author(s):  
Paola Bassani ◽  
Carlo Alberto Biffi ◽  
Riccardo Casati ◽  
Adrianni Zanatta Alarcon ◽  
Ausonio Tuissi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Aluminium Alloys ◽  
Al Alloys ◽  
Laser Melting ◽  
Microstructural Refinement ◽  
Manufacturing Techniques

Analysis of peculiar properties offered by Al alloys produced according to additive manufacturing techniques, specifically by Selective Laser Melting (SLM), is carried out. Two alloys are considered, derived by casting (AlSi10Mg) and by wrought (ENAW 2618) applications. The SLM processed samples are investigated considering their microstructural and mechanical properties after SLM and compared to cast and wrought counterparts. A strong microstructural refinement induced by SLM processing is observed for both alloys, resulting in excellent hardness properties. Investigation on integrity of samples revealed that small-size microvoids and unmelted regions could be present in SLM parts.

An Investigation of Process Parameters on Selective Laser Melting of Nitinol

2013 ◽  
Author(s):  
Jason Walker ◽  
Mohammad Elahinia ◽  
Christoph Haberland
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Material Behavior ◽  
Laser Melting ◽  
Direct Fabrication ◽  
Shape Memory Effects ◽  
Near Net Shaping ◽  
Net Shaping ◽  
Actuation Systems

Nitinol’s superelastic and shape memory effects can be used in passive or active actuation systems. Often used in the aerospace industry, the use of Nitinol for actuation is also growing in the biomedical fields and elsewhere. However, the industry currently lacks the ability to produce complex Nitinol actuators, which is strictly limiting its potential. The extreme difficulty of machining Nitinol complicates manufacturing processes. Furthermore, the transformation temperatures which drive Nitinol’s unique behavior are extremely sensitive to the relative concentrations of nickel and titanium. Therefore, exceptionally tight compositional control during production is necessary to guarantee ideal material behavior. Additive manufacturing (AM) is a near-net-shaping technology which allows for the direct fabrication of complex metallic components. In this way, the (lack of) machinability of Nitinol is no longer an issue because no traditional machining is required during fabrication. Using AM also enables production of 3D geometries that are not possible using traditional techniques. Features such as engineered porosity, hollow parts, curved holes and filigree structures are suddenly realizable. Furthermore, direct CAD fabrication reduces the timescale of the concept-to-prototype transition. A major breakthrough in additive manufacturing came with the development of fiber laser technology in the mid-1990’s, which enables direct melting of manufacturing grade metals into fully dense parts. This technology became known as selective laser melting (SLM). Despite its huge potential, SLM of Nitinol has received little attention from the engineering world. In the present work, two different SLM machines (Realzier SLM 100 and Phenix Systems PXM) are used to develop Nitinol components directly from powder. Adjustment and optimization of the process parameters on the product are analyzed and compared.

Formation of Structural-Phase State in a Cobalt-Chromium-Molybdenum Alloy by Selective Laser Melting

2021 ◽  
Vol 313 ◽  
pp. 50-58
Author(s):  
A.A. Saprikin ◽  
Yurii P. Sharkeev ◽  
Natalya A. Saprykina ◽  
Margarita A. Khimich ◽  
Egor A. Ibragimov
Keyword(s):  
Low Temperature ◽  
Selective Laser Melting ◽  
Mechanical Engineering ◽  
Stable Phase ◽  
Temperature Phase ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
Machine Parts ◽  
Cobalt Chromium Molybdenum ◽  
Low Temperature Phase

Heat resistant cobalt-based alloys have found a specific niche in the present-day mechanical engineering due to their unique properties. To begin with, cobalt-based alloys are used as corrosion, heat and wear resistant materials intended for aggressive environments and operation at extreme temperatures, e.g. blades, nozzles, swirlers, rings and other elements of turbines and internal combustion engines. Traditional molding methods applied in the mechanical engineering fail to provide necessary operational and technological characteristics of aforementioned machine parts. Owing to selective laser melting it is possible to reduce a production time and manufacturing costs for machine elements with a complex physical configuration and generate an alloy with an extraordinary structure, which is not found in traditionally combined compounds. A structure of cobalt exists in two crystal modifications: a hexagonal close-packed epsilon phase, a low-temperature phase and a face-centered cubic lattice gamma phase, a high-temperature phase. The alloy hardness is directly related to an amount of a low-temperature phase. The laser melting shortens a laser beam impact time on a powder composition due to a higher power and laser travelling speed. A high value of heat conductivity seems to be the reason for rapid solidification and cooling, which, in their turn, increase a percent of an alpha-martensite phase in an alloy and improve the hardness and wear resistance of machine parts. The reported paper summarizes studies aimed at the development of a stable phase structure three-component alloy (Сo-66 mass % Cr-6 mass % Mo) based on the cobalt-chromium-molybdenum system and mixed up via selective laser melting.

The Mechanism of Forming Coagulated Particles in Selective Laser Melting of Cobalt-Chromium-Molybdenum Powder

2020 ◽  
Vol 839 ◽  
pp. 79-85 ◽  
Author(s):  
Alexander A. Saprykin ◽  
Yuriy P. Sharkeev ◽  
Natalya A. Saprykina ◽  
Egor A. Ibragimov
Keyword(s):  
Selective Laser Melting ◽  
Powdered Material ◽  
Beam Diameter ◽  
Molybdenum Powder ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
Movement Velocity ◽  
Scanning Velocity ◽  
Preheating Temperature ◽  
Cobalt Chromium Molybdenum

Selective laser melting (SLM) is thought to be a prospective manufacturing technology of complex metal components. Formation of coagulated particles when melting is reported to be an important factor for target mechanical properties of the end product. This paper discusses the effect of SLM parameters, including laser output power, laser movement velocity, preheating temperature of the powder, laser beam diameter on the mechanism of forming coagulated particles in melting cobalt-chromium-molybdenum powdered material. The study shows that a rise of power to 60 W at a scanning velocity 6 mm/s causes coagulated particles to expand to 350 μm; that is far bigger than a size of powder in as delivered state (90 μm). The work investigates the effect of mechanical activation of cobalt-chromium-molybdenum powder on dimensions of coagulated particles. The research data can be applied to the improvement of up-to-date optimization approaches to manufacturing process parameters in SLM technology.

Processing of Ti Alloys by Additive Manufacturing: A Comparison of the Microstructures Obtained by Laser Cladding, Selective Laser Melting and Electron Beam Melting

2013 ◽  
Vol 765 ◽  
pp. 413-417 ◽  
Author(s):  
Sylvie Reginster ◽  
Anne Mertens ◽  
Hakan Paydas ◽  
Jerome Tchoufang Tchuindjang ◽  
Quentin Contrepois ◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Heat Flow ◽  
Selective Laser Melting ◽  
Electron Beam Melting ◽  
Laser Melting ◽  
Ti Alloys ◽  
Manufacturing Techniques ◽  
Microstructural Anisotropy ◽  
Ultrafast Cooling

In this study, samples of alloy Ti-6Al-4V have been processed by different additive manufacturing techniques in order to compare the resulting microstructure. In all three processes, ultrafast cooling gives rise to strongly out-of-equilibrium microstructures. However, the specific of the heat flow in each process lead to significant differences as far as the grains orientation and the resulting microstructural anisotropy are concerned.

scholarly journals A novel workflow for indirect cobalt-chromium restorations using additive manufacturing without digital design

2021 ◽  
Vol 15 (3) ◽  
pp. 147-151
Author(s):  
Les Kalman ◽  
Lyndsay Desimone
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Surface Finish ◽  
Preliminary Investigation ◽  
Digital Design ◽  
Conventional Approach ◽  
Cobalt Chromium ◽  
Intraoral Scanner ◽  
Laser Melting

This preliminary investigation explored additive manufacturing to fabricate cobalt-chromium onlay restorations without the use of digital design. Extracted molars were prepared for four-surface onlays followed by the conventional approach for the fabrication of provisionals. The provisionals were digitized with an intraoral scanner, and stereolithography (STL) files were fabricated with additive manufacturing in cobalt-chromium, utilizing selective laser melting (SLM). Onlays were bonded to the corresponding tooth. Restorations were polished after cementation and assessed with photography, radiography, and a clinical post-cementation checklist. Cementation was unremarkable; marginal adaption and surface finish were generally acceptable. A simple, efficient, and inexpensive alternative workflow for the fabrication of indirect restorations without using the digital design is proposed.

scholarly journals Selective Laser Melting: Materials and Applications

2020 ◽  
Vol 4 (1) ◽  
pp. 13 ◽  
Author(s):  
Konda Gokuldoss Prashanth
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
The Future ◽  
Manufacturing Techniques

Additive manufacturing (AM) is one of the emerging manufacturing techniques of immense engineering and scientific importance and is regarded as the technique of the future [...]

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