Abstract
The introduction of Additive Manufacturing (AM) is changing the way in which components and machines can be designed and manufactured. Within this context, designers are taking advantage of the possibilities of producing parts via the addition of material, defining strategies, and exploring alternative design or optimization solutions (i.e., nonviable using subtractive technologies) of critical parts (e.g., gears and shafts). However, a safe and effective design requires specific resistance data that, due to the intrinsic modernity of additive technologies, are not always present in the literature. This paper presents the results of an experimental campaign performed on gear-samples made by 17-4 PH and produced via Laser Powder Bed Fusion (PBF-LB/M). The tests were executed using the Single Tooth Bending Fatigue (STBF) approach on a mechanical pulsator. The fatigue limit was determined using two different statistical approaches according to Dixon and Little. The obtained data were compared to those reported in the ISO standard for steels of similar performance. Additional analyses, i.e., Scanning Electron Microscopy SEM, were carried out to provide a further insight of the behavior 17-4PH AM material and in order to investigate the presence of possible defects in the tested gears, responsible for the final failure.
Highlights
Published: 28 March 2021Since their introduction on the market in the late 1980s, 3D printing technologies have been shown to be an important growth factor in moving from the production of prototypes up to the possibility of producing metal parts with full structural properties [1].It has been proven that Additive Manufacturing (AM) technologies are cheaper than the traditional ones, but only in case of small batch productions [2,3,4,5,6] or of parts not realizable via traditional technologies [5]; these are the reasons why designers are looking for the possibilities of designing and producing parts via AM
It is of interest to compare the results of the present experimental campaign with the classical gear literature data aiming at evaluating the applicability of AM technologies in the context of gearbox design
As an example, according to the aforementioned code, the bending fatigue limit σFE in the case of hardened wrought steel of medium quality (ME), at 1% failure probabilities and without considering any correction factors, typically ranges between 425 and 500 MPa, values comparable with the ones found in this experimental campaign
Summary
Published: 28 March 2021Since their introduction on the market in the late 1980s, 3D printing technologies have been shown to be an important growth factor in moving from the production of prototypes up to the possibility of producing metal parts with full structural properties [1].It has been proven that Additive Manufacturing (AM) technologies are cheaper than the traditional ones, but only in case of small batch productions [2,3,4,5,6] or of parts not realizable via traditional technologies [5]; these are the reasons why designers are looking for the possibilities of designing and producing parts via AM. Since their introduction on the market in the late 1980s, 3D printing technologies have been shown to be an important growth factor in moving from the production of prototypes up to the possibility of producing metal parts with full structural properties [1]. AM, allows the realization of parts with geometry that cannot be realized via the traditional production processes, such as, for instance, internal cavities and lattice structures. With a specific focus on metallic AM gears, in [7] a methodology to realize a lightweight gear by modifying the gear body is proposed. A tooth lightweight design is proposed in [8], in [9,10] a gear with internal cooling channel is shown, and in [11] the gear Noise
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