scholarly journals Multiscale Analysis of Surface Texture Quality of Models Manufactured by Laser Powder-Bed Fusion Technology and Machining from 316L Steel

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2794
Author(s):  
Damian Gogolewski ◽  
Tomasz Bartkowiak ◽  
Tomasz Kozior ◽  
Paweł Zmarzły
Keyword(s):  
Multiscale Analysis ◽  
Wavelet Transformation ◽  
316L Stainless Steel ◽  
Multiscale Methods ◽  
Fusion Technology ◽  
Current Standard ◽  
Statistical Research ◽  
Powder Bed ◽  
316L Steel

The paper presents the results of tests aimed at evaluating the surface textures of samples manufactured from material based on 316L stainless steel. The analysis of the surface topography was conducted based on the classical approach in accordance with the current standard and with the use of multiscale methods; i.e., wavelet transformation and geometric via curvature. Selective laser melting 3D printing technology was used to produce samples for surface testing. Furthermore, additional assessment of surfaces created as result of milling was conducted. Statistical research demonstrated a differentiation in the distribution of particular morphological features in certain ranges of the analyzed scales.

scholarly journals Waviness of Freeform Surface Characterizations from Austenitic Stainless Steel (316L) Manufactured by 3D Printing-Selective Laser Melting (SLM) Technology

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4372 ◽  
Author(s):  
Tomasz Kozior ◽  
Jerzy Bochnia ◽  
Paweł Zmarzły ◽  
Damian Gogolewski ◽  
Thomas G. Mathia
Keyword(s):  
Fusion Technology ◽  
Surface Waviness ◽  
Stainless Steel 316L ◽  
Laser Melting ◽  
High Corrosion Resistance ◽  
Powder Bed ◽  
316L Steel ◽  
Optical Profilometer ◽  
Made In

The paper presents the results of tests of surface waviness of samples made in the powder bed fusion technology. The models were built using 316L steel-based powder with high corrosion resistance. The samples were placed on the construction platform at three different angles (0°, 45°, 90°) in XZ plane. Then, using an optical profilometer, the parameters of the geometric structure of the surface of the primary profile and the separated waviness component were measured. Analyzing the results of the test, it can be stated that the orientation of model arrangement has an impact on the quality of the technological surface texture, what has significance impact on wear processes and mechanical properties.

scholarly journals Thermal Environment and Inclination Angle Dependencies on the Surface Quality of Selective Laser Melted 316L Steel

2017 ◽  
Vol 372 ◽  
pp. 202-207 ◽  
Author(s):  
Leonhard Hitzler ◽  
Johann Hirsch ◽  
Markus Merkel ◽  
Andreas Öchsner
Keyword(s):  
Surface Quality ◽  
316L Stainless Steel ◽  
Thermal Environment ◽  
Powder Bed ◽  
Economic Decisions ◽  
Staircase Effect ◽  
316L Steel ◽  
Inclination Angles ◽  
Steel Surfaces

Additive manufacturing processes offer the ability to manufacture highly complex geometries, but are limited in terms of the achievable surface quality. These limitations are based on physical restrictions, especially the need of support and the powder-bed environment, and economic decisions. In this study, the development of the morphology of surfaces with varying inclination angles was investigated on the example of 316L stainless steel. Surfaces with low inclination angles to the manufacturing plane suffered extensively from the process related staircase effect, whereas perpendicular side faces revealed high dependencies on the interaction with the powder-bed.

scholarly journals The Influence of Printing Orientation on Surface Texture Parameters in Powder Bed Fusion Technology with 316L Steel

Micromachines ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 639 ◽  
Author(s):  
Tomasz Kozior ◽  
Jerzy Bochnia
Keyword(s):  
Surface Texture ◽  
Microelectromechanical Systems ◽  
Powder Bed Fusion ◽  
Additive Technology ◽  
Powder Bed ◽  
Texture Parameters ◽  
316L Steel ◽  
Spatial Parameters ◽  
The Impact

Laser technologies for fast prototyping using metal powder-based materials allow for faster production of prototype constructions actually used in the tooling industry. This paper presents the results of measurements on the surface texture of flat samples and the surface texture of a prototype of a reduced-mass lathe chuck, made with the additive technology—powder bed fusion. The paper presents an analysis of the impact of samples’ orientation on the building platform on the surface geometrical texture parameters (two-dimensional roughness profile parameters (Ra, Rz, Rv, and so on) and spatial parameters (Sa, Sz, and so on). The research results showed that the printing orientation has a very large impact on the quality of the surface texture and that it is possible to set digital models on the building platform (parallel—0° to the building platform plane), allowing for manufacturing models with low roughness parameters. This investigation is especially important for the design and 3D printing of microelectromechanical systems (MEMS) models, where surface texture quality and printable resolution are still a large problem.

scholarly journals Micro-Range Actuation by Pressure-Induced Elastic Deformation of 316L Steel Membranes Produced by Laser Powder Bed Fusion

Actuators ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 296
Author(s):  
Florian Fettweis ◽  
Bjorn Verrelst ◽  
Svend Bram
Keyword(s):  
316L Stainless Steel ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Actuation Force ◽  
Thin Walls ◽  
316L Steel ◽  
Fundamental Research ◽  
Membrane Type ◽  
Metrology System

In this paper, fundamental research is performed on membrane type actuators made out of 316L stainless steel, manufactured with Laser powder bed fusion (LPBF). A total of six membranes with membrane thicknesses ranging from 0.6 mm up to 1.2 mm were scanned using a high precision metrology system to measure the membrane for displacement at different actuating pressures. The membranes were furthermore investigated for roughness, porosity and thickness. This showed that the thinnest membranes skewed in the print direction when actuated. The remaining membranes achieved higher specific displacements than finite element simulations (FES) predicted, due to surface roughness and porosity. Membrane type actuators can be used for precise actuation within the micrometre range. LPBF allows the creation of internal pockets and membranes in a single metal piece. In opposition to the more commonly used polymers for membrane-type actuators, LPBF steel printed parts offer high stiffness and actuation force. However, due to limitations of the LPBF process on thin walls, large deviations from FES occur. In this paper, a CAD and FES compensation strategy is suggested, which makes future, more complex and effective, designs possible.

Evaluation of medical care for Diabetic and Hypertensive patients in primary care in Mexico: Observational retrospective study (Preprint)

2020 ◽  
Author(s):  
Agustin Lara-Esqueda ◽  
Sergio A Zaizar-Fregoso ◽  
Violeta M Madrigal-Perez ◽  
Mario Ramirez-Flores ◽  
Daniel A Montes-Galindo ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Medical Care ◽  
Serum Lipids ◽  
Quality Care ◽  
Premature Death ◽  
Current Standard ◽  
Anonymized Data ◽  
Quality Of Medical Care

BACKGROUND Diabetes Mellitus is a worldwide health problem and the leading cause of premature death with increasing prevalence over time. Usually, along with it, Hypertension presents and acts as another risk factor that increases mortality risk. Both diseases impact the country's health while also producing an economic burden for society, causing billions of dollars to be invested in their management. OBJECTIVE The present study evaluated the quality of medical care for patients diagnosed with diabetes mellitus (DM), hypertension (HBP), and both pathologies (DM+HBP) within a public health system in Mexico, according to the official Mexican standard for each pathology. METHODS 45,498 patients were included from 2012 to 2015. All information was taken from the electronic medical records database, exported as anonymized data for research purposes. Each patient record was compared against the standard to test the quality of medical care. RESULTS Glycemia with hypertension goals reached 29.6% in DM+HBP, 48.6% in DM, and 53.2% in HBP. The goals of serum lipids were reached by 3% in DM+HBP, 5% in DM, and 0.2% in HBP. Glycemia, hypertension, and LDL cholesterol reached 0.04%. 15% of patients had an undiagnosed disease of diabetes or hypertension. Clinical follow-up examinations reached 20% for foot examination and clinical eye examination in the whole population. Specialty referral reached 1% in angiology or cardiology in the whole population. CONCLUSIONS Goals for glycemic and hypertension reached 50% in the overall population, while serum lipids, clinical follow-up examinations, and referral to a specialist were deficient. Patients who had both diseases had more consultations, better control for hypertension and lipids, but inferior glycemic control. Overall, quality care for DM and/or HBP has not been met according to the standards. While patients with DM and HBP do not have a current standard to evaluate their own needs.

scholarly journals The effects of locations on the build tray on the quality of specimens in powder bed additive manufacturing

2021 ◽  
Author(s):  
Snehashis Pal ◽  
Nenad Gubeljak ◽  
Tonica Bončina ◽  
Radovan Hudák ◽  
Teodor Toth ◽  
...  
Keyword(s):  
Main Role ◽  
Particle Sizes ◽  
Additional Experiment ◽  
Powder Bed ◽  
Melt Pool ◽  
Start Line ◽  
Sample Density ◽  
Powder Layering ◽  
Pool Formation

AbstractIn this study, the effect of powder spreading direction was investigated on selectively laser-melted specimens. The results showed that the metallurgical properties of the specimens varied during fabrication with respect to their position on the build tray. The density, porosity, and tensile properties of the Co–Cr–W–Mo alloy were investigated on cuboid and tensile specimens fabricated at different locations. Two different significant positions on the tray were selected along the powder spreading direction. One set of specimens was located near the start line of powder spreading, and the other set was located near the end of the building tray. The main role in the consequences of powder layering was played by the distribution of powder particle sizes and the packing density of the layers. As a result, laser penetration, melt pool formation, and fusion characteristics varied. To confirm the occurrence of variations in sample density, an additional experiment was performed with a Ti–6Al–4V alloy. Furthermore, the powders were collected at two different fabricating locations and their size distribution for both materials was investigated.

scholarly journals Telerehabilitation Intervention in Patients with COVID-19 after Hospital Discharge to Improve Functional Capacity and Quality of Life. Study Protocol for a Multicenter Randomized Clinical Trial

2021 ◽  
Vol 18 (6) ◽  
pp. 2924
Author(s):  
José-Manuel Pastora-Bernal ◽  
María-José Estebanez-Pérez ◽  
Guadalupe Molina-Torres ◽  
Francisco-José García-López ◽  
Raquel Sobrino-Sánchez ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Clinical Trial ◽  
Randomized Clinical Trial ◽  
Hospital Discharge ◽  
Study Protocol ◽  
Functional Capacity ◽  
Treatment Method ◽  
Current Evidence ◽  
Current Standard

COVID-19 can cause important sequels in the respiratory system and frequently presents loss of strength, dyspnea, polyneuropathies and multi-organic affectation. Physiotherapy interventions acquire a fundamental role in the recovery of the functions and the quality of life. Regarding the recovery phases after hospital discharge, the current evidence available is very preliminary. Telerehabilitation is presented as a promising complementary treatment method to standard physiotherapy. The main objective of this research is to evaluate the effectiveness of a personalized telerehabilitation intervention after discharge from hospital for the improvement of functional capacity and quality of life compared to a program of health education and/or care in a rehabilitation center. As secondary objectives, to identify the satisfaction and perception of patients with the telerehabilitation intervention and the presence of barriers to its implementation, as well as to evaluate the cost-effectiveness from the perspective of the health system. This study protocol will be carried out through a single blind multicenter randomized clinical trial in the south of Spain. We hypothesize that the implementation of a telerehabilitation program presents results not inferior to those obtained with the current standard intervention. If the hypothesis is confirmed, it would be an opportunity to define new policies and interventions to address this disease and its consequences. Trial registration NCT04742946.

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