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Analytical and Experimental Approaches to Shot Peening Prawoto, Yunan; Mazein, P G; Kosterin, A V
Jurnal Internasional Penelitian Teknologi Terapan Vol 1 No 1 (2020): April 2020
Publisher : Bandung State Polytechnic (Politeknik Negeri Bandung)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35313/ijatr.v1i1.20

Abstract

This paper is a first attempt on analytical approach to shot peening. Shot peening improves the surface engineering quality by eliminating the tool marks, such as machining, grinding, stamping and other surface defects. Most importantly, the improvements of shot peening are produced by combination of compressive stress and cold work. Compressive stresses are beneficial in increasing resistances to fatigue failures, while the cold work effects of shot peening treatments can increase the surface hardness. Although shot peening is extensively used in the industry, its academic understanding is very low. Shot peening has been considered as a black art and black engineering in the industry. The focus of this research is to layout foundation of the shot peening research in academic world. Only then, will the research propel more systematically rather than via the conventional industrial trial and error approach. In this research, analytical approach with experimental verification is presented.
Manufacturing Process beyond Conventional Plasticity Theory: Case Study in Manufacturing Low Spring Index Coil Prawoto, Yunan; Manville, Sonia; Sakai, T; Tanaka, M; Gnauple-Herold, T
Jurnal Internasional Penelitian Teknologi Terapan Vol 1 No 2 (2020): October 2020
Publisher : Bandung State Polytechnic (Politeknik Negeri Bandung)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35313/ijatr.v1i2.32

Abstract

In the academic world, conventional plasticity theory limits the cold process due to energy inefficiency, material properties and residual stress that may inhibit the quality of a product, and therefore usually not recommended. However, industrial competition pushes that limits against the edge. Knowing the consequences in advance helps reducing the damage that may have been caused by such a violation. This paper shows an example in the form of a case study. A coil spring with a very low spring index that academically suggested to be made using hot process was attempted to be manufactured using cold coiling machine. The case study shows that although it is possible, extra careful and timely handling must be done to successfully manufacture it. A coil with excessive residual stress is shown in this paper. That residual stress alone was capable in damaging the coil during manufacturing. The defect takes place after coiling and before tempering process. A fracture mechanics was used to analyze the failure, which is the splitting due to excessive residual stress. The case study also shows that the problem can be solved by speedy and subsequent stress relieve annealing process.