This article focuses on wear tests of spur gears made with the use of additive manufacturing techniques from thermoplastic materials. The following additive manufacturing techniques were employed in this study: Melted and Extruded Modelling (FDM) and Fused Filament Fabrication (FFF). The study analysed gears made from ABS M-30 (Acrylonitrile Butadiene Styrene), ULTEM 9085 (PEI Polyetherimide) and PEEK (Polyetheretherketone), and the selection of these materials reflects their hierarchy in terms of economical application and strength parameters. A test rig designed by the authors was used to determine the fatigue life of polymer gears. Gear trains were tested under load in order to measure wear in polymer gears manufactured using FDM and FFF techniques. In order to understand the mechanism behind gear wear, further tests were performed on a P40 coordinate measuring machine (CMM) and a TalyScan 150 scanning instrument. The results of the gear tests made under load allow us to conclude that PEEK is resistant to wear and gear train operating temperature. Its initial topography undergoes slight changes in comparison to ABS M-30 and Ultem 9085. The biggest wear was reported for gears made from Ultem 9085. The hardness of the material decreased due to the loaded gear train’s operating temperature.
17 January 2019 in Strojniški vestnik - Journal of Mechanical Engineering
The paper presents geometrical accuracy tests of polymer spiral bevel gears. The change in geometry was quantified with reference to research models produced by incremental methods: FDM (fused deposition modeling), SLS (selective laser sintering), DLP (digital light processing) and PolyJet. Model geometry verification was made basing on the INDUSTRY 4.0 philosophy using the Klingelnberg P40 coordinate measuring machine (CMM) operating in an integrated network system. The graphs show deviations of selected parameters defining the geometry of the teeth. Analysis of the obtained results was used to select the appropriate printing technology and to improve the quality of the polymer gears. The highest 11th accuracy class of the spiral bevel gear teeth, determined according to DIN 3965, was obtained for models manufactured in PolyJet additive technology.
The durability of cylindrical spur gears made of ABS and PU manufactured using the FDM (Fused deposition modeling) additive method and vacuum casting was investigated. The tests were carried out for pairs of gears with an involute profile for three values of the profile angle: 20, 25 and 30° to determine the effect of the profile angle on the gear operation time. The effect of running-in on gear durability was also assessed.
Properties of polymer gears were tested using coordinate measurement methods. This study is a follow-up to research on geometric accuracy of gears manufactured by injection molding. Spur gears were measured on a coordinate measuring machine running the GINA software by Klingelnberg. Measurement results were output in the form of measurement sheets which included values required in the DIN 3962 standard. The article also analyses the topography of test gear teeth. The topography was presented for a single tooth of the gear and determined on the basis of the measurements of 9 profiles distributed evenly over a specific profile assessment interval (interval Lα defined in the standard) and 7 tooth traces located within a relevant tooth trace assessment interval (interval Lβ defined in the standard). All gears tested in this study were placed outside accuracy class 12.
The present paper describes modern methodology of the bevel gear design with a particular focus on issues concerning the theoretical basis and the preparation of the numerical simulation of the machining. The assumptions used in developing the mathematical model of cutting teeth are given and an example of the teeth flank surfaces of a gear and a pinion resulting from the virtual processing is shown. The correctness of the mathematical model of cutting teeth was verified by comparing the resulting based on the model grid points, the side of the tooth surface, resulting from the simulation cutting teeth in CAD. A high convergence of the two surface geometry was demonstrated, which allows for the use of the analysis for each of the models independently.