1,720,990 research outputs found
HNCR model following robust approach
No full textThis paper introduces a new model for Non-Conformity Management, aimed at overcoming the limitations occurring when dealing with Non-Conformities through traditional methods like Root Cause Analysis. The need to suggest a new approach to Non-Conformities Management is connected to those situations where a large variety of Non-Conformities is recorded, with a significant number of low-impacting ones; addressing them directly through methods like Root Cause Analysis would often be not economically viable. In this context, the paper discusses Holistic Non-Conformities Reduction (HNCR) approach as a suitable option to address this kind of business situations. In particular, the contribution of this paper is related to the development of HNCR model and the evaluation of how to properly structure the model and the flow that shall be followed. By clustering Non-Conformities into flexible categories to be easily modified, expanded and rearranged through time, the HNCR model allows to identify new critical Non-Conformity families, otherwise hardly detectable. A proof of concept relative to HNCR deployment is presented: 2 different scenarios are introduced, the first being the Non-Conformities management within the extended supply chain of a large pharmaceutical distribution centre, while the second deals with Non-Conformities in the context of a company's new programs development
Investigations of Fatigue Damage in a Nitriding Low-Carbon Bainitic Steel for High-Performance Crankshaft
Full text linkIn the automotive environment, the need to increase the performance of materials requires extra engineering efforts. The possibility of developing new materials is strategically important. Indeed, alternative solutions in terms of material choice allow designers to optimise their projects and keep competitive production costs. Traditional quenched and tempered steels are usually used for highly stressed components, and possible alternatives could be important competitive opportunities. One possible substitute is using bainitic steels to exploit their economic advantages while maintaining acceptable mechanical performances. This paper explores the fatigue life behaviour of a new low-carbon bainitic steel for applications requiring case hardening treatment obtained by the nitriding process. A high-cycle fatigue (HCF) strength assessment is conducted through a test campaign to compare treated and untreated material. The improvement in fatigue strength is evaluated as well as the study of fracture surfaces, residual stress, and microhardness profiles to assess in detail the effectiveness of the nitriding process. It is found that the nitriding leads to an improvement in fatigue life but not as much as expected because of the low ductile behaviour of this steel, the high speed of stress application added, and the embrittlement of the nitriding treatment, as confirmed through fracture surface analysis
Laser Powder Bed Fusion: A Review on the Design Constraints
Full text linkWith the creation of additive manufacturing production lines and the adoption of additive technologies, such as Laser Powder Bed Fusion, as standard manufacturing technologies for the mass production of parts, many considerations arise. In particular, product quality assurance is surely a very important aspect to be considered when talking about mass production. Laser powder bed fused parts are characterized by specific characteristics, such as quite rough surfaces and internal cavities filled with powder after the part construction. The need to ensure part quality and the importance to guarantee quality to all the parts made within the production line highlights the need to design the part addressing all the criticalities resulting from the manufacturing process, in addition to the ones related to the operative conditions. In this work, the attention is placed on two important topics: part surface inspectability and part cleaning. In particular, part inspectability is a crucial aspect in determining part coherence with design specifications. Part production via LPBF puts interpretability issues in inspecting the parts. Part cleaning is a crucial topic as well. Part cleaning is related to the design of the part to guarantee a correct powder evacuation from all the internal channels and cavities. Within the work, problems will be defined and design guidelines will be proposed to manage these topics
Comparative evaluation of fuzzy axiomatic design and IAMS comprehensive VIKOR approaches for material selection in mechanical design
Full text linkIn the mechanical design, the selection among material alternatives has become a pressing issue due to the progressive growth in the complexity of mechanical systems, in search of continuous increase in performance and the presence of a wide range of possible materials. Moreover, there are many requests for projects, and this makes the choice of material a decisive activity for the success or failure of the project itself. This paper makes a comparative evaluation of two important approaches to identify the best materials alternatives: The C-VIKOR and the Fuzzy Axiomatic Design. The work considers as a case study the selection of the material for the production of the valve seats in a high-performance engine. An evaluation of the results obtained is made to show the peculiarity of each of the two approaches
Integral aided method for material selection based on quality function deployment and comprehensive VIKOR algorithm
No full textIn engineering design, the selection of material alternatives usually depends of different criteria based on the specific problem. Due to the different units of this criteria, a normalization process is needed in the selection model. A lot of normalization approach can be found in literature and at the same time many algorithms have been developed to ensure the optimal material selection for a certain industrial application. Two elements of reflection can be drawn from the analysis of these. The first is the absence of an aided support to the selection of the correct engineering criteria by whom operate the selection process. The second is the need to define a weighting method that at the same time can be user-friendly to use and representative of the project's needs. A new selection model based on the integration between House of Quality and the Comprehensive Vikor Algorithm is presented in this paper. This approach, called Integral Aided Material Selection (IAMS), can overcome the main lack of traditional material selection model and provide a real support tool to the project team. That way the project team can optimally choose the selection criteria and assign to these the correct priority coherently with the project needs. A case study is presented to illustrate and justify the proposed method. The topic of the case study concerns the identification of the best coating for the protection of an aluminum alloy substrate (Al-7075) from the effects of abrasive wear against an alternating counterpart made by a high-strength cast iron. © 2012 Elsevier Ltd
Design and testing of a MRF rotational damper for vehicle applications
No full textAdaptive dampers are an interesting solution for conjugating the necessity of controllable devices and low power consumption. Magneto-rheological fluids (MRF) can be profitably employed in adaptive dampers because of the significant variation of fluid parameters with magnetic field properties. This paper focuses on the design process of an innovative rotational MR damper specifically created to be placed in the front-wheel suspension of a compact car. The advantages of the rotational damper and the definition of the optimal design are described. The proposed damper significantly reduces several key problems associated with MR devices: the quantity of fluid required, the sedimentation of ferromagnetic particles in the suspension and the abrasion of the seals. In fact, with this solution, low average working pressure, low flow velocity through valves, a wide range of variable damping characteristics, and high durability of the damper can be achieved. Thanks to this innovative component, different new architectures for adaptive suspension systems can be developed to have a planar distribution of the suspension components with a consequent space optimization and size reduction in the vertical direction. © 2010 IOP Publishing Ltd
Thermal design considerations for a L-PBF built metal component: effects of Inter-Layer Cooling Time, Preheating Temperature and Gas Flow
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Integration of Holistic Non-conformities Management and Axiomatic Design: A case study in Italian Income Tax Returns Management
Full text linkIn the last few years, the Italian Welfare State has suffered from the effects of the serious economic crisis. The crisis has hastened the need to cut down the public expenditures. The current study focuses on the improvement of the effectiveness, the efficiency and the inexpensiveness of those processes related to the management of the tax services provided by medium/large withholding agents. The proposed method aims to improve handling Non-Conformities in a process, by introducing a project plan based on the Axiomatic Design methodology. This method aids in producing a set of robust planning solutions for a wide range of issues. Starting from the reported issues emailed to the Customer Support Service of the process, it is possible to catalogue the encountered issues through an Holistic Non Conformity Reduction approach, so that introduces such a level of abstraction necessary to define Non-Conformities of process in a basic and logical way. Then, we turn to the Axiomatic Design methodology in an iterative way and we find the set of planning solutions, which are more logically suitable to the operating context. In practice, this allows innovative and sustainable clustering approaches, making the development of proactive lessons learned possible. These can be used both in the development and in debugging of the information systems supporting the process management, ensuring an enhanced robustness against the frequent changes related to legislative measures and the forecasts adopted
- …
