1,721,148 research outputs found
Improving Tool-Life Stochastic Control Through a Tool-Life Model Based on Diffusion Theory
No full textIt is known that estimating the wear level at a future time instant and obtaining an updated evaluation of the tool-life density is essential to keeping machined parts at the desired quality level, reducing material waste, increasing machine availability, and guaranteeing the safety requirements. In this regard, the present paper aims at showing that the tool-life model that Braglia and Castellano [23] developed can be successfully adopted to probabilistically predict the future tool wear and to update the tool-life density. Thanks to the peculiarities of a stochastic diffusion process, the approach presented allows deriving the density of the wear level at a future time instant, considering the information on the present tool wear. This makes it therefore possible updating the tool-life density given the information on the current state. The method proposed is then experimentally validated, where its capability to achieve a better exploitation of the tool useful life is also shown. The approach presented is based on a direct wear measurement. However, final considerations give cues for its application under an indirect wear estimate
Diffusion theory applied to tool-life stochastic modeling under a progressive wear process
No full textIn this paper a novel approach to the derivation of the tool-life distribution, when the tool useful life ends after a progressive wear process, is presented. It is based on the diffusion theory and exploits the Fokker-Planck equation. The Fokker-Planck coefficients are derived on the basis of the injury theory assumptions. That is, tool-wear occurs by detachment of small particles from the tool working surface, which are assumed to be identical and time-independent. In addition, they are supposed to be small enough to consider the detachment process as continuous. The tool useful life ends when a specified total volume of material is thus removed. Tool-life distributions are derived in two situations: (i) both Fokker-Planck coefficients are time-dependent only, and (ii) the diffusion coefficient is neglected and the drift is wear-dependent. Theoretical results are finally compared to experimental data concerning flank wear land in continuous turning of a C40 carbon steel bar adopting a P10 type sintered carbide insert. The adherence to the experimental data of the tool-life distributions derived exploiting the Fokker-Planck equation is satisfactory. Moreover, the tool-life distribution obtained when the diffusion coefficient is neglected and the drift is wear-dependent is able to well-represent the wear behavior at intermediate and later times
Stakeholders’ Influence and Internal Championing of Product Stewardship in the Italian Food Packaging Industry
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Shortcomings and Benefits Associated with the Implementation of MRP Packages: a Survey Research
No full textTowards a Taxonomy of Search Patterns of Manufacturing Flexibility in Small and Medium-Sized Firms
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Computer-Aided Activity Planning (CAAP) in Large-Scale Projects With an Application in the Yachting Industry
No full textThe present paper provides the schema for an innovative and
modular computer-based approach to the planning of activities in largescale projects. Such projects are characterized by tens of thousands of tasks, which are consequently burdensome and difficult to plan manually. This is true to the point that in many shipyards only a low level of detail is used and poor planning is generally performed. The proposed approach is called Computer-Aided Activity Planning (CAAP), and an application in the yachting industry is shown to demonstrate its effectiveness. In particular, the so-called outfitting planning problem is faced. The CAAP system, taking into account the available shipyard resources and the knowledge on the building rules is able to automatically define, sequence, and schedule the activities of the whole outfitting process acting as a "planning configurator". Moreover, it allows the industry-specific knowledge to be stored, maintained and shared within the (extended) organization. Owing to these "building blocks", plans can be defined accurately and in a shorter time starting from pre-defined templates, with particular impact on lead times whenever variations to complex projects are needed. Finally, to verify the actual capabilities of the approach, the CAAP was implemented within a prototypical software called NautiCAAP
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