scholarly journals Effect of plasma nitriding of austenitic stainless steel produced by direct metal laser sintering

2021 ◽  
Vol 27 (4) ◽  
pp. 190-194
Author(s):  
Dorina Kovács ◽  
Dávid Miklós Kemény
Keyword(s):  
Surface Roughness ◽  
Raw Materials ◽  
Plasma Nitriding ◽  
Austenitic Stainless Steels ◽  
Laser Sintering ◽  
Direct Metal Laser Sintering ◽  
Direct Current Plasma ◽  
Wide Range ◽  
Optical Electron

A special additive manufacturing (AM), called as Direct Metal Laser Sintering (DMLS), is a technology that produces 3D workpieces using a wide range of different metals as raw materials. The aim of current research is to investigate the plasma nitriding effect on the DMLS produced samples. The direct current plasma nitriding treatment was achieved at 440 °C for 4 hours with 75%N2 – 25%H2 gas mixture. Before the treatment, the 316L austenitic stainless steels samples were ground with different methods to modify the surface roughness. Scanning electron microscope (SEM), X-ray diffractometer, glow discharge optical electron spectroscopy, Vickers microhardness tester and potentiodynamic corrosion test were used for the characterization of surface properties. The results demonstrated that the surface roughness did not affect the outcome of the plasma nitriding, but the corrosion resistance increases with the decrease of the surface roughness compared to the untreated 3D sample.

scholarly journals Characterization of Polysaccharidic Associations for Cosmetic Use: Rheology and Texture Analysis

Cosmetics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 62
Author(s):  
Giovanni Tafuro ◽  
Alessia Costantini ◽  
Giovanni Baratto ◽  
Stefano Francescato ◽  
Laura Busata ◽  
...  
Keyword(s):  
Raw Materials ◽  
Immersion Test ◽  
High Viscosity ◽  
Natural Polymers ◽  
Public Attention ◽  
First Choice ◽  
Wide Range ◽  
Textural Parameters ◽  
Complementary Techniques

As public attention on sustainability is increasing, the use of polysaccharides as rheological modifiers in skin-care products is becoming the first choice. Polysaccharide associations can be used to increase the spreading properties of products and to optimize their sensorial profile. Since the choice of natural raw materials for cosmetics is wide, instrumental methodologies are useful for formulators to easily characterize the materials and to create mixtures with specific applicative properties. In this work, we performed rheological and texture analyses on samples formulated with binary and ternary associations of polysaccharides to investigate their structural and mechanical features as a function of the concentration ratios. The rheological measurements were conducted under continuous and oscillatory flow conditions using a rotational rheometer. An immersion/de-immersion test conducted with a texture analyzer allowed us to measure some textural parameters. Sclerotium gum and iota-carrageenan imparted high viscosity, elasticity, and firmness in the system; carob gum and pectin influenced the viscoelastic properties and determined high adhesiveness and cohesiveness. The results indicated that these natural polymers combined in appropriate ratios can provide a wide range of different textures and that the use of these two complementary techniques represents a valid pre-screening tool for the formulation of green products.

scholarly journals Structural characterization of biomedical Co–Cr–Mo components produced by direct metal laser sintering

2015 ◽  
Vol 48 ◽  
pp. 263-269 ◽  
Author(s):  
G. Barucca ◽  
E. Santecchia ◽  
G. Majni ◽  
E. Girardin ◽  
E. Bassoli ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Laser Sintering ◽  
Direct Metal Laser Sintering

scholarly journals Process Optimization Variables for Direct Metal Laser Sintering

2015 ◽  
Vol 15 (4) ◽  
pp. 38-51 ◽  
Author(s):  
Ż. A. Mierzejewska
Keyword(s):  
Selective Laser Sintering ◽  
Minimum Energy ◽  
Systems Design ◽  
Laser Sintering ◽  
Physical Models ◽  
Cad Model ◽  
Direct Metal Laser Sintering ◽  
3D Cad ◽  
Short Period ◽  
Wide Range

AbstractManufacturing is crucial to creation of wealth and provision of quality of life. Manufacturing covers numerous aspects from systems design and organization, technology and logistics, operational planning and control. The study of manufacturing technology is usually classified into conventional and non-conventional processes. As it is well known, the term "rapid prototyping" refers to a number of different but related technologies that can be used for building very complex physical models and prototype parts directly from 3D CAD model. Among these technologies are selective laser sintering (SLS) and direct metal laser sintering (DMLS). RP technologies can use wide range of materials which gives possibility for their application in different fields. RP has primary been developed for manufacturing industry in order to speed up the development of new products (prototypes, concept models, form, fit, and function testing, tooling patterns, final products - direct parts). Sintering is a term in the field of powder metallurgy and describes a process which takes place under a certain pressure and temperature over a period of time. During sintering particles of a powder material are bound together in a mold to a solid part. In selective laser sintering the crucial elements pressure and time are obsolete and the powder particles are only heated for a short period of time. SLS uses the fact that every physical system tends to achieve a condition of minimum energy. In the case of powder the partially melted particles aim to minimize their in comparison to a solid block of material enormous surface area through fusing their outer skins. Like all generative manufacturing processes laser sintering gains the geometrical information out of a 3D CAD model. This model is subdivided into slices or layers of a certain layer thickness. Following this is a revolving process which consists of three basic process steps: recoating, exposure, and lowering of the build platform until the part is finished completely.

scholarly journals Tensile Properties Characterization of AlSi10Mg Parts Produced by Direct Metal Laser Sintering via Nested Effects Modeling

Materials ◽  
2017 ◽  
Vol 10 (2) ◽  
pp. 144 ◽  
Author(s):  
Biagio Palumbo ◽  
Francesco Del Re ◽  
Massimo Martorelli ◽  
Antonio Lanzotti ◽  
Pasquale Corrado
Keyword(s):  
Tensile Properties ◽  
Laser Sintering ◽  
Direct Metal Laser Sintering ◽  
Properties Characterization

Rapid Manufacturing with Direct Metal Laser Sintering

2002 ◽  
Vol 758 ◽  
Author(s):  
J-E. Lind ◽  
J. Hanninen ◽  
J. Kotila ◽  
O. Nyrhila ◽  
T. Syvanen
Keyword(s):  
Surface Roughness ◽  
Layer Thickness ◽  
Process Development ◽  
Die Casting ◽  
Laser Sintering ◽  
Thin Layers ◽  
Rapid Manufacturing ◽  
Manufacturing Processes ◽  
Direct Metal Laser Sintering ◽  
Process Work

ABSTRACTThe term Rapid Manufacturing is today very often used as a substitute for Rapid Prototyping, because the manufacturing processes and materials have developed so much that the parts produced with the machines can even be used as functional production parts. For Direct Metal Laser Sintering (DMLS) this was enabled by the introduction of the powders for 20 micron layer thickness; steel-based powder in 2001 and bronze-based powder in 2002. Successful rapid manufacturing with DMLS does not only mean the reduction of layer thickness, but it is a sum of many factors that had to be optimized in order to make the process work with the 20 micron layer thickness: the metal powder behavior in very thin layers is not the same as with thicker layers, the demands for the support structures are higher and the possibility of using multiples of the layer thickness gives additional freedom. By optimizing the process parameters the UTS values for the steel-based powder increased up to 600 MPa and for the bronze-based powder up to 400 MPa. At the same time the surface roughness (Ra) values after shot peening were 3 microns and 2 microns, respectively. Although using thinner layers also increases the building time the advantage is gained in drastically reduced finishing times due to increased surface quality and detail resolution. Typical geometries produced by DMLS are difficult-to-manufacture components and components typically produced by P/M or even by die-casting. The paper covers the development aspects in both material and process development and also presents some realized case studies.

scholarly journals Different methods for characterizing surface roughness using laser speckle technique

2019 ◽  
Vol 12 (23) ◽  
pp. 21-29
Author(s):  
Mayada B. Al-Quzweny
Keyword(s):  
Surface Roughness ◽  
Speckle Pattern ◽  
Point Of View ◽  
Laser Speckle ◽  
Image Texture ◽  
Object Surface ◽  
Image Texture Analysis ◽  
Measuring Surface ◽  
Wide Range

In this work, results from an optical technique (laser speckle technique) for measuring surface roughness was done by using statistical properties of speckle pattern from the point of view of computer image texture analysis. Four calibration relationships were used to cover wide range of measurement with the same laser speckle technique. The first one is based on intensity contrast of the speckle, the second is based on analysis of speckle binary image,  the third is on size of speckle pattern spot, and the latest one is based on characterization of the energy feature of the gray level co-occurrence matrices for the speckle pattern. By these calibration relationships surface roughness of an object surface can be evaluated within these relations ranges from single speckle pattern image which was taken from the surface.

Mass Finishing of Parts Produced by Direct Metal Laser Sintering

Volume 3 ◽  
2004 ◽  
Author(s):  
A. Boschetto ◽  
F. Veniali ◽  
F. Miani
Keyword(s):  
Surface Roughness ◽  
Industrial Process ◽  
Mechanical Action ◽  
Laser Sintering ◽  
Main Process ◽  
Direct Metal Laser Sintering ◽  
Complicated Shape ◽  
Mass Finishing ◽  
Barrel Finishing ◽  
Established Technique

This paper presents some practical considerations on finishing of parts made by direct metal laser sintering (DMLS). The main process capabilities limitations of this promising rapid tooling technique are in fact in the surface roughness of the produced parts. This fact hinders the introduction of DMLS as a widely employed industrial process, especially for what concerns the production of moulds and inserts and allows their use only as preseries tools in injection moulding of plastics, since the requirements for preseries tools are worse than those needed during the process. Barrel finishing, in turn, is a well established technique to improve the roughness of parts of complicated shape by means of a soft mechanical action over the surface. The results herewith presented show that it is possible to achieve roughness of the order of 1 μm Ra even when starting from initial roughness of the order of 15 μm Ra, i.e. those typically attained by DMLS.

scholarly journals An Analysis of the Surface Geometric Structure and Geometric Accuracy of Cylindrical Gear Teeth Manufactured with the Direct Metal Laser Sintering (DMLS) Method

2019 ◽  
Author(s):  
Jadwiga Małgorzata Pisula ◽  
Grzegorz Budzik ◽  
Łukasz Przeszłowski
Keyword(s):  
Surface Roughness ◽  
Geometric Structure ◽  
Gear Tooth ◽  
Spur Gear ◽  
Laser Sintering ◽  
Tooth Surface ◽  
Direct Metal Laser Sintering ◽  
Cylindrical Gear ◽  
Sand Blasting ◽  
Gear Teeth

This paper presents findings concerning the accuracy of the geometry of cylindrical spur gear teeth manufactured with the direct metal laser sintering (DMLS) method. In addition, the results of the evaluation of the tooth surface geometric structure are presented in the form of selected two-dimensional and three-dimensional surface roughness parameters. An analysis of the accuracy of the fabricated gear teeth was performed after gear sand-blasting and gear tooth milling processes. Surface roughness was measured before and after sand-blasting and gear tooth milling. The test gear wheel was manufactured from GP1 high-chromium stainless steel on an EOS M270 machine.

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