To increase the efficiency of a gearbox, research on gear mesh loss is of importance. Britton et al. concluded that the surface finishing method affects the gear mesh efficiency. The efficiency ...benefits of superfinishing a surface and reducing the surface roughness have been reported by Kahraman. A novel method for calculating the bearing loss torque was proposed by Tu et al. Andersson et al. found that the efficiency can vary between 2 and 5% during repeated efficiency tests due to variations in the assembly process. This work investigates how the honing surface finishing process and DIN 3962 quality class affect the gear mesh efficiency by performing tests in an FZG back-to-back test rig. Two materials, a powder metal and a wrought steel, were tested. All gears were finished using a honing process and sorted according the measured quality class. Powder metal gears of class 6, 7, 8, and ≥9 and wrought steel gears of class 6, 7, and ≥9 were tested. The efficiency were calculated from measuring the torque required to maintain a constant velocity of the FZG test rig. The results from the efficiency tests showed no significant difference in efficiency between the wrought steel and powder metal steel gears. In addition, no obvious correlation between the DIN 3962 quality class and the gear mesh efficiency could be found. When examining the wrought steel material it was found that the reproducibility of the efficiency was comparable to the assembly error of the test rig, despite the variation in quality class.
Titanium Powder Metallurgy contains the most comprehensive and authoritative information for, and understanding of, all key issues of titanium powder metallurgy (Ti PM). It summarizes the past, ...reviews the present and discusses the future of the science and technology of Ti PM while providing the world titanium community with a unique and comprehensive book covering all important aspects of titanium powder metallurgy, including powder production, powder processing, green shape formation, consolidation, property evaluation, current industrial applications and future developments. It documents the fundamental understanding and technological developments achieved since 1937 and demonstrates why powder metallurgy now offers a cost-effective approach to the near net or net shape fabrication of titanium, titanium alloys and titanium metal matrix composites for a wide variety of industrial applications.
Provides a comprehensive and in-depth treatment of the science, technology and industrial practice of titanium powder metallurgyEach chapter is delivered by the most knowledgeable expert on the topic, half from industry and half from academia, including several pioneers in the field, representing our current knowledge base of Ti PM. Includes a critical review of the current key fundamental and technical issues of Ti PM.Fills a critical knowledge gap in powder metal science and engineering and in the manufacture of titanium metal and alloys
This paper investigates the resistance of micropitting on two materials, using an FZG back-to-back test rig with C-PT gears. The materials are wrought steel (16MnCr5) and a commercial powder ...metallurgical material (Astaloy™ Mo). Two finishing methods were studied: grinding and superfinishing. Experimental results show that the superfinishing prevented micropitting, but led to premature failure due to cracks in the root caused by tip-to-root interference. Micropitting was initiated at a higher load stage for the powder metallurgical steel compared to the ground wrought steel. The failure mechanisms were similar between materials with the same surface finish. The powder metallurgical steel showed subsurface initiated fatigue compared to the wrought ground steel having surface-initiated fatigue. Testing new finishing methods and materials, one has to be aware of the influence of the gear micro geometry.
•The use of in-situ surface profile measurements can be used for evaluating the progress of micropitting damage.•Quantitative profile measurements were used to track damage initiation on the tooth flank during a pitting test.•The lack of tip relief in FZG pitting tests can lead to failure of the surface if the surface has low surface roughness.•The damage on ground wrought and powder metal gears are similar, but the powder metal gears also show subsurface damage.
A new powder production method has been developed to speed up the search for novel alloys for additive manufacturing. The technique involves an ultrasonically agitated cold crucible installed at the ...top of a 20 kHz ultrasonic sonotrode. The material is melted with an electric arc and undergoes pulverization with standing wave vibrations. Several different alloys in various forms, including noble and metallic glass alloys, were chosen to test the process. The atomized particles showed exceptional sphericity, while powder output suitable for additive manufacturing reached up to 60%. The AMZ4 metallic glass powder remained amorphous below the 50 μm fraction, while tungsten addition led to crystallization in each fraction. Minor contamination and high Mn and Zn evaporation, especially in the finest particles, was observed in atomized powders. The innovative ultrasonic atomization method appears as a promising tool for material scientists to develop powders with tailored chemical composition, size and structure.
Developing of a 3D Printer to Produce Parts Using Powder Metal Faraj, Suhad Kamal; Salloom, Maher Yahya; Khalid, Enas Abd-alkarim
International journal on advanced science, engineering and information technology,
08/2020, Letnik:
10, Številka:
4
Journal Article
Recenzirano
The additive manufacturing (AM) process or three-dimensional printing (3DP) process is making stereoscopic shapes using a layered system. There are several materials used for printing such as ...plastic, wood, metal as powder, filament, liquid, or others, and there are also different ways for printing. Recently, the focus has been on metal printing, but the problem is that the high energy used such as laser, electron beam, or high heat to melt the metal to print it as required. For this reason, the price of 3D printers for metal is very expensive. In this paper, the design and implementation of a 3D printer for metal parts production are worked. The work also includes making an experimental test for the new 3D printer and printing 3D metal parts without using heat. In this work, Tevo-Tarantula 3D printer has been modified in terms of software and hardware. Two new extruders are designed to inject the metal powder and adhesive, where the heat was removed from the extruder head and the printer bed. The metal powder extruder contains a powder reservoir, glass funnel, and access valve where controlled through the solenoid valve. The adhesive extruder is controlled using a simple hydraulics. The printing process was done by printing two layers of metal powder and a layer of adhesive depending on the desired shape to create 3D objects using the SolidWorks software. Different metal models were printed and these models were compared with the original design which was drawing by SolidWorks software. The difference between the actual model drawing and the printed parts is differences between (0.004 mm) for some parts to (2.3 mm) for other parts or the percentage of error is between (0.1% - 4%) for the printed parts. However, the material can be used in high temperatures, where rubber materials cannot be used, and in applications requiring porosity.
Radiation thermometry techniques have been implemented to measure thermal signatures in powder bed fusion (PBF) additive manufacturing (AM), including the use of imaging devices with a large field of ...view, to measure large areas of the powder bed with spatial discrimination, and those considered single spot devices that measure signatures from a small region. Traditionally, these techniques can be categorized as single-color (brightness) or two-color (ratio) pyrometry; imaging devices are single-color while spot devices can be either. Both techniques can be used to infer a target temperature using a priori knowledge of the emissivity or employing the graybody assumption of constant emissivity across the spectrum. However, the dynamics of PBF AM, where a concentrated heat source is employed to selectively melt powder material, lead to complex material phase transitions under non-equilibrium solidification conditions. This makes it challenging to measure accurate thermal signatures because the emissivity of the target is also constantly varying as the PBF process unfolds. In this work, we employed an established technique of multi-wavelength pyrometry in an electron beam powder bed fusion (PBF-EB) system to continuously measure temperatures and the thermal emissive behavior during sintering and melting of an Inconel 625 powder that was subjected to preheating by direct scanning with the electron beam. The measurements displayed distinctive changes in signal strength or emissivity (in the wavelength range between 1080 nm and 1640 nm) that indicated the material phase change from loose to sintered powder to molten material and finally to solidified material; these changes in signal strength/emissivity were correlated with electron microscopy observations. This work highlights the suitability of multi-wavelength (MW) pyrometry as an in situ diagnostic tool to identify thermal process signatures (i.e., absolute temperatures), and the radiative emissive behavior of the materials being processed. Several demonstrations of the use of this MW pyrometry technique as a diagnostic tool are provided, illustrating its ability to sense signal strength/emissivity differences as the material experiences changes due to its temperature, phase, morphology, and chemistry. Although spatial and temporal improvements in the technique can be pursued, the sensitivity of the approach is demonstrated, as an example, in the ability to capture the passing thermal wavefronts arising from the scanning electron beam. It is anticipated that this technique and the information it provides can be leveraged in the development of advanced techniques for thermal monitoring and process control in PBF.
Metal iron powder is a promising new energy source that is of significant practical and research interest for future automotive power systems. However, the shapes of the particles are typically ...assumed to be spherical or an equivalent sphere when estimating the specific impulse of motors. Such an assumption lacks objectivity and can result in unreasonable estimations of two-phase flow losses. In order to better optimize the design of an engine, this study focuses on the influence of non-spherical particles (such as ellipsoidal and cuboid particles) on the characteristics of nozzle two-phase flow. Models for the governing equations of nozzle two-phase flow are developed to conduct a theoretical study to analyze the combustion properties of iron oxide particles and flow in the nozzle. In addition, experimental studies involving nanometer iron-powder particle combustion and engine thrust measurements are conducted to validate the results obtained from numerical calculations that are conducted using a fourth order Runge–Kutta–Gill method. The results indicate that particle morphology, size, and coagulation content play a significant role in the motor performance and the two-phase flow losses. Specifically, the hypothesis of the ellipsoidal model is in better agreement with the experimental findings compared to the other particle models.
Elemental analysis of fine powder metals and their mixtures using plasma ball spectroscopy has been developed. This method is suitable for in situ and on-site industrial/ non-industrial monitoring ...applications; pre-treatment or powder fixation methods which are necessary for laser-induced breakdown spectroscopy were not required. The metals analysed were Cu, Mo and Pb with average grain size of ≤75 μm. A plasma seed (generated by laser or spark discharge) was spatially sustained in air at atmospheric conditions in a spherical form and controlled temporally using a semiconductor microwave (MW) oscillator; hence, the name plasma ball. The frequency and output power range of continuously oscillated MW were 2.45 GHz and 20–150 W respectively. Longer lifetime, controllability, non-thermal and stable plasma generation, as well as comparatively large volume of MW-sustained plasma made PBS of powder metals practically possible. Calibration curves were obtained for Cu-Mo and Cu-Pb mixtures, from which the concentration limit of detection (LOD) for both Mo and Pb powders were obtained as a function of the MW oscillation duration. The optimum concentration LOD for Mo and Pb powders in their constituent mixtures were respectively 0.004% and 0.002% by weight.
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•Semiconductor oscillated MW (2.45 GHz) enhances spectral intensity of induced plasmas.•Microwave-sustained plasma is suitable for direct elemental analysis of powder metals.•Concentration LOD was 0.004% and 0.002% by weight for Mo and Pb powders respectively.
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