Machines. Technologies. Materials.
Vol. 14 (2020), Issue 8

Table of Contents

  • MACHINES

  • TECHNOLOGIES

    • Mechanical finger prosthesis design and manufacturing by modern technologies

      pg(s) 348-351

      The article deals with the use of CAD software and additive technology to produce a simple, low-cost mechanical finger prosthesis. The goal was to use SOLIDWORKS and Cura software to design and manufacture an index finger prosthesis from PLA (polylactic acid) material, using an FFF (Fused Filament Fabrication) desktop 3D printer Bq WitBox. The mechanical finger prosthesis is used for flexion and extension performance of the missing joints to enable lost gripping function. The designed prosthetic finger has a simple construction consisting of components made on a 3D printer and its movement functions are initiated by specifically attached cable system. The practical part of the paper contains procedures for prototype and final version design, manufacturing and testing. The prototype was designed to imitate healthy finger digits movement initiated by the specific cable system. Final version of the finger prosthesis has been designed after the successful flexion/extension system testing. The design of the components was modified to resemble a healthy finger and a socket has been added to the prosthesis. Flexion and extension performance of the prosthesis was tested using cables of different diameters. After summarizing the results, it has been confirmed that the prosthesis can be easily applied to the arm and its dimensions, construction and movement correspond to an anatomically healthy finger and that 3D printing is a technology suitable for efficient and fast production of individual prosthesis components, which is an indisputable advantage compared to the traditional method of prosthesis production.

    • Optimization of the electron beam welding of Steel 45 samples

      pg(s) 352-355

      An experimental study of the geometrical characteristics of the cross sections of the thermally affected areas obtained by electron beam welding of carbon steel 45 is made. The thermally affected zone and the molten area of the welds from non-stainless steels corresponds to a zone where the physical-mechanical properties and the microstructure of the processed material are changed after the processing. The process parameters that were changed during the experiments are: welding speeds were 0.5, 1.0 and 1.5 cm/sec, the beam current was changed in the range of 30 – 133 mA and the focus position was changed from 72 mm above the sample surface to 62 mm below the sample surface. The accelerating beam voltage was 50 kV. The geometry of the weld in the cases of a deep penetrating electron beam and narrow thermally affected zone is investigated. Electron beam welding process parameter optimization is performed, based on the estimation of regression models. In such way the electron beam optical systems can be tested and the specific quality requirements for the welds obtained by electron beam welding can be fulfilled

    • Survey of the geometric characteristics of a test specimen before punch sharpenings

      pg(s) 356-359

      This article analyses the widths and thicknesses of the test specimen after operating the punch before sharpening the guillotine blades. The principle of operation of a 3D computer tomograph with an accuracy of 3μm is considered. The analysis will be performed in two ways: by using a micrometer and a caliper and by using a 3D computed tomography for determining the width and thickness

  • MATERIALS