National Repository of Grey Literature 60 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Influencing the surface roughness of materials created by the SLM technique and the influence of roughness on macroscopic properties
Rotter, Marek ; Havlík, Petr (referee) ; Jan, Vít (advisor)
Theses resumes the principle of SLM method and submits the most used materials for this technology and its properties. The main issue is influencing the surface roughness of these materials, when the electro-chemical polishing in the concentrated sulfuric acid was used with five difference options. It was observed, that the roughness is caused by two factors, fused nonmelted grains of metal powder and layered structure. Polishing at 8 V, 0,5 A and after 40 min was the best results, when the smooth wave surface was achieved. The Ra parameter descended from initial 5,0 m to 3,9 m after this polishing. One of the factors, which causes the high roughness, was eliminated.
Effect of layer thickness on critical angle of additively manufactured lattice structures
Nosek, Jakub ; Vrána, Radek (referee) ; Vaverka, Ondřej (advisor)
Aim of this work is to describe the effect of a layer thickness on critical angel of a lattice structures manufactured by SLM technology. The effect of layer thickness was investigated on single struts and on lattice structures made from stainless steel 316L. Better geometrical accuracy could be obtained, if the smaller layer thickness is used. Less attached powder particles on downskins was also observed on lattice structures. Thanks to this thesis, it is possible to determine, if it is meaningful to decrease the layer thickness in order to improve manufacturability of lattice structures even with higher manufacturing time.
Geometric Accuracy of Additively Manufactured Test Parts
Ilčík, Jindřich ; Sehnoutka, Petr (referee) ; Koutný, Daniel (advisor)
The presented diploma thesis deals with the control of the geometric accuracy of the parts produced by additive manufacturing technology selective laser melting. The paper first analyzed the work of the other authors dealing with this issue. Based on obtained informations from this analysis were developed benchmark test parts for quality control of production on a commercial machine SLM 280 HL supplied by SLM Solutions GmbH. The work was carried out several tests to determine the appropriate parameters of construction parts. These tests, their results and conclusions are fully described in this papper.
The use of small punch tests for materials with a higher level of structural inhomogeneity
Gordiak, Michal ; Řehořek, Lukáš (referee) ; Válka, Libor (advisor)
Master's thesis deals with evaluating applicability of correlation relationships between material characteristics determined by Small Punch Test and standard tensile test for material AlSi7Mg0,6 manufactured by casting and technology SLM. Results of Small Punch Tests are correlated with yield strength, tensile strength, elongation, and Young's modulus of elasticity. For each material characteristic various correlation methods are compared, while for each method corresponding coefficients are determined. Consequently, the applicability of individual methods is evaluated by substituting coefficients determined by various studies. Primarily analyzed are correlation methods for which future normalization is expected. The results of master's thesis show that structural inhomogeneity caused by SLM process does not result in high inaccuracies in determining material characteristics. Larger impact on material characteristics has high porosity, which was identified in cast material and led to significant deviations in evaluating tensile strength and elongation.
Determination of Material Properties of Specimens Produced by Metallic 3D Printing
Zakl, Alexandr ; Peterková, Eva (referee) ; Řiháček, Jan (advisor)
This bachelor's thesis deals with mechanical properties and current status of 3D printing of metal parts, especially by DMLS/SLM method. Research part is dedicated to various technologies and suppliers in the field of 3D printing with emphasis on printing metal methods. Main purpose of this thesis is to connect the worlds of 3D printing and 3D optical measuring of deformation, so the part of research segment is dedicated to optical measuring and leading innovative company GOM. One of the leading product of this company is ARAMIS and in the context of this thesis it was present during the experiment as a instrument for measuring and inspecting material characteristics, and is present in research part where is mentioned a principle on which this device is working (digital image correlation) as is the device itsself. In the experimental part of this thesis, samples were printed on DMLS printer from company XactMetal, which were then submitted to a tensile test. Measurement was done using DIC based device ARAMIS and inspected for basic material properties in same named program.
Processing of Inconel 939 alloy using laser powder bed fusion at elevated temperatures
Hertl, David ; Dočekalová, Kateřina (referee) ; Malý, Martin (advisor)
The thesis deals with the problem of Inconel 939 alloy processing by SLM technology using base plate preheating. The main objective of the work is to verify the effect of base plate preheating on residual stresses. The problem was solved by two approaches: process simulation, and subsequent experimental verification. The process simulation with preheating temperature of 400 °C achieved the highest agreement with the experiment with a deviation of 4.1 %. Based on the experiment, a suitable base plate preheating temperature of 100 °C was determined to reduce the deformation and residual stresses. By processing Inconel 939 using preheating temperatures of 100 °C and 400 °C, static mechanical properties comparable to those of the standard components processed by SLM technology from Inconel 939 after the heat treatment were achieved. These results offer the potential for significant reductions in overall production time and costs associated with manufacturing Inconel 939.
Heat treatment of aluminum alloy AlSi7Mg0,6 fabricated by metal 3D printing
Zabloudil, Jan ; Malý, Martin (referee) ; Koutný, Daniel (advisor)
Author tries to obtain new information about the influence of different heat treatments on SLM fabricated AlSi7Mg0,6 alloy, its mechanical properties and residual stress. For this purpose were chosen parameters of heat treatment based on previous research of other authors. With the use of normalised tensile strength test specimens and special specimens for analysis of deformation caused by the residual stress were the influences studied. Author checked the influence of stress relieving annealing, parameters of precipitation hardening and artificial ageing on mechanical properties and residual stress in the material. Results can help fabrication of studied material to receive required properties and eliminate the deformation caused by the residual stress.
Universal muzzle device for an assault rifle
Rušar, Filip ; Majzlík, Pavel (referee) ; Vtípil, Jaroslav (advisor)
This diploma thesis deals with the design of a universal muzzle device for the assault rifle. The device is designed to produce Selective Laser Melting. The main objective is the elimination negative effects of gunshot. The paper explores possibilities of using porous structures for this type of equipment. The influence of individual types of porous structures on the flow of gases is monitored. The universal muzzle device itself is optimized using CFD analyzes. The device was made using SLM technology and experimentally verified. His impact on the impact, gun lift, noise and flame elimination was investigated.
Cavitation erosion mechanisms
Kotoulová, Helena ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
Předložená bakalářská práce se zabývá mechanismy kavitační eroze a je rozdělena na dvě hlavní části. Teoretická část popisuje princip kavitace, způsob jejího vzniku a především kolaps kavitačních bublin, který negativně ovlivňuje povrch obtékaného tělesa (např. na hydraulických strojích). Z tohoto důvodu je nutné podrobně studovat účinky kavitační eroze. Experimentální část je věnována testování kavitační eroze na kovových a plastových vzorcích vytisknutých na 3D tiskárně. Plastové vzorky byly srovnávány navzájem mezi sebou, kovové vzorky z 3D tiskárny se vzorky odlitými. O vlivu kavitační eroze na součásti vytisknuté na 3D tiskárně je stále ještě málo informací, i když se jedná o velmi progresivní a stále častěji používaný typ výroby.
Stainless steels for cryogenic applications processed by 3D printing
Grygar, Filip ; Hutař, Pavel (referee) ; Koutný, Daniel (advisor)
This thesis deals with properties of austenitic stainless steel 304L processed by SLM technology and tested at room and cryogenics temperatures. Result is description of mechanical properties and microstructure. First step was to develop processing parameters to achieve porosity of prints fell below 0,01 %. Following tensile test showed higher yield and ultimate tensile strength than conventionally fabricated parts, even at temperature -80 °C, but at cost of reduced ductility. Due to deformation and low temperature austenite transformed into martensite. This transformation also occurred in Charpy toughness test, that resulted in ductile to brittle behaviour.

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