| 1. |
- Agic, Adnan, 1967-, et al.
(författare)
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Experimental analysis of cutting edge effects on vibrations in end milling
- 2019
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Ingår i: CIRP - Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 24, s. 66-74
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Tidskriftsartikel (refereegranskat)abstract
- The ability to minimize vibrations in milling by the selection of cutting edge geometry and appropriate cutting conditions is an important asset in the optimization of the cutting process. This paper presents a measurement method and a signal processing technique to characterize and quantify the magnitude of the vibrations in an end milling application. Developed methods are then used to investigate the effects of various cutting edge geometries on vibrations in end milling. The experiments are carried out with five cutting edge geometries that are frequently used in machining industry for a wide range of milling applications. The results show that a modest protection chamfer combined with a relatively high rake angle has, for the most of cutting conditions, a reducing effect on vibration magnitudes. Furthermore, dynamics of a highly positive versus a highly negative cutting geometry is explored in time domain and its dependency on cutting conditions is presented. The results give concrete indications about the most optimal cutting edge geometry and cutting conditions in terms of dynamic behavior of the tool.
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| 2. |
- Beglarzadeh, B., et al.
(författare)
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Modelling and indirect measurement of machine tool equivalent joint compliances
- 2021
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Ingår i: CIRP - Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 35, s. 882-895
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Tidskriftsartikel (refereegranskat)abstract
- Machine tools require high geometric accuracy and stiffness. Both of these characteristics affect the radius of a radially loaded circular test. By using various loads, the machine's volumetric compliance can be studied as a function of position, orientation, and load. Further processing of the data using a kinematic and compliance model of the machine allows the equivalent joint compliances to be estimated. This model also allows to produce the characteristic patterns of loaded telescopic double ball bar readings associated with each compliance term. The compliance model contains numerous superfluous and confounded terms that are pruned from the model. The analytical model is then used to produce a numerical identification Jacobian that is further applied to estimate the compliances from test data gathered at various force levels. By using all force data at once global compliance values are estimated whereas using only adjacent force level data allows observing the change in compliance with force. The new nomenclature is introduced where each compliance term has three subscripts. The first subscript is the direction of the displacement, the second subscript is the applied force direction, and the third subscript is the relevant joint or axis. The dominant compliances are the X-axis on-axis compliance CXXX (confounded with the lateral compliance of the Y-axis CXXY) and CYYY (confounded with CYYX). It is observed that as the load increases from 76 to 706 N (by increments of 126 N), the dominant compliances increase by around 5%. Type A uncertainties of the calculated compliances are estimated from repeated measurements and are found to be relatively small. Some non-dominant compliances, such as the torsional compliance of the Y-axis CCCY account for deflection of less than 0.5% of that for the main compliances and has a negative value which is mechanically unexpected. It is explained in detail in the results and discussion section.
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| 3. |
- Bertoni, Alessandro, 1985-, et al.
(författare)
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PSS cost engineering : A model-based approach for concept design
- 2020
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Ingår i: CIRP - Journal of Manufacturing Science and Technology. - : Elsevier. - 1755-5817 .- 1878-0016. ; 29:Part: B, s. 176-190
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Tidskriftsartikel (refereegranskat)abstract
- Manufacturing companies are increasingly moving toward delivering combinations of products and services to provide higher value to their customers. The development of such Product Service Systems (PSS) escalates in complexity when several products developed by different suppliers need to be integrated into a unique system. For first tier suppliers, it is a great challenge to model and simulate the impact of changing design variables at the micro-level on both hardware properties and governing behaviours of services over the entire life-cycle of the PSS. The paper describes a model-based approach developed to estimate the life cycle cost of a PSS hardware already at a concept design stage. The proposed approach computes the relative cost efficiency of a set of design variants using as input the data generated by the simulations run in the Computer Aided Engineering (CAE) environment. The approach allows the exploration of the design space of a PSS given by the variation of the geometry of a Computer Aided Design (CAD) model, building on the computation of customised cost modules selected by a generic list of PSS cost dimensions. For each evaluated design case, the model produces as output a unique monetary figure of the cost expected to incur by owning or using the asset throughout the lifetime. The work has been conducted in collaboration with a tier-one aerospace component manufacturer, and the application of the model is exemplified through a case study related to the development of a turbine rear structure (TRS) for commercial jet engines. The approach is most suitable for the development of complex systems in which new products and components are integrated into a shared product platform. The results are discussed in relation to the current literature on PSS cost engineering, highlighting challenges to be addressed to increase cost estimation accuracy and increase uncertainty identification and awareness.
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| 4. |
- Bertoni, Alessandro, et al.
(författare)
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Value-driven product service systems development : Methods and industrial application
- 2016
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Ingår i: CIRP - Journal of Manufacturing Science and Technology. - : Elsevier. - 1755-5817 .- 1878-0016. ; 15, s. 42-55
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Tidskriftsartikel (refereegranskat)abstract
- In recent times a service-dominant logic is permeating the design of complex systems. However, in spite of their appeal, initiatives such as Product Service Systems (PSS) have not become mainstream, and methods are lacking to support this transition. This paper argues that methodological guidance, as well as tools for decision support, may be found in the research field of Value Driven Design (VDD), which originates in the realm of Systems Engineering. The paper objective is to elaborate on gaps and opportunities for cross-pollination between VDD and PSS. The results of a systematic review of methods and tools for design decision support highlight the opportunity for introducing optimization models derived from VDD in the PSS design process, while the latter can enrich VDD research with a more qualitative value assessment logic. The paper summarizes this integration in a methodological approach, and exemplifies its application in case studies mainly from the aerospace and road construction equipment sector.
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| 5. |
- Bonilla Hernández, Ana Esther, et al.
(författare)
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Integrated optimization model for cutting data selection based on maximal MRR and tool utilization in continuous machining operations
- 2016
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Ingår i: CIRP - Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 13, s. 46-50
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Tidskriftsartikel (refereegranskat)abstract
- The search for increased productivity can be interpreted as the increase of material removal rate (MRR). Namely, increase of feed, depth of cut and/or cutting speed. The increase of any of these three variables, will increase the tool wear rate; therefore decreasing its tool life according to the same tool life criteria. This paper proposes an integrated model for efficient selection of cutting data for maximal MRR and maximal tool utilization. The results show that, it is possible to obtain a limited range of cutting parameters from where the CAM Programmer can select the cutting data assuring both objectives.
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| 6. |
- Dahl, Martin, 1984, et al.
(författare)
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Interactive formal specification for efficient preparation of intelligent automation systems
- 2022
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Ingår i: CIRP Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 38, s. 129-138
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Tidskriftsartikel (refereegranskat)abstract
- The automation system of the future will consist of an increasing amount of complex resources, such as collaborative robots and/or autonomously roaming robots for material handling. To control these devices in an environment shared with human operators require state of the art computer perception and motion planning algorithms to be used as part of the automation system. This new type of intelligent automation system, where intelligent machines and learning algorithms are replacing more traditional automation solutions, requires new methods and workflows to keep up with the increase in complexity. This paper presents an interactive and iterative framework for solving some of these new challenges. The framework supports model-based control system preparation performed simultaneously to preparation of 3D geometries, positioning of robots, and tool design. The workflow enables an interactive preparation process, where new resources and constraints can be added to a live (real or simulated) automation system and control system failures can be analyzed in familiar tools for virtual preparation. Additionally, the paper describes how the integrated preparation process was applied to reconfiguring an industrial use case that includes a collaborative robot working side by side with a human operator, smart tools, and a vision system for localizing both work objects and tools.
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| 7. |
- de Andrade Schwerz, Claudia, 1992, et al.
(författare)
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A neural network for identification and classification of systematic internal flaws in laser powder bed fusion
- 2022
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Ingår i: CIRP Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 37, s. 312-318
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Tidskriftsartikel (refereegranskat)abstract
- Quality control of mechanical components is crucial to ensure their expected performance and prevent their failure. For components manufactured additively, quality control performed in-process is particularly interesting, as the sequential deposition and remelting of layers represent a possibility to mitigate existing flaws. The first step towards closed-loop control is to ensure that the monitoring setup and the data analytics approach can flag and discriminate flaws. This study aims to assess the potential of a layerwise monitoring system associated with a supervised machine learning approach to identify and classify internal flaws in laser powder bed fusion of Hastelloy X. For that, systematically generated internal flaws were mapped ex-situ in 72 distinct process conditions. The outputs of the near-infrared long-exposure acquisition system were labeled according to the ex-situ characterization and used to train a fully convolutional neural network. The network was then used to classify previously unseen monitoring images into three classes, according to the predominant flaw type expected, lack of fusion, keyhole porosity, or residual porosity. Accuracy, precision and recall over 96% are obtained, indicating that the monitoring system combined with this supervised machine learning approach successfully identifies and classifies internal flaws.
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| 8. |
- Erdem, Ilker, 1987, et al.
(författare)
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A novel comparative design procedure for reconfigurable assembly fixtures
- 2017
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Ingår i: CIRP Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 19, s. 93-105
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Tidskriftsartikel (refereegranskat)abstract
- While market requirements demand that manufacturing systems increase their responsiveness, assembly fixtures remain limited in corresponding to the same demand. Fixture designers as practitioners are left without guidance to design reconfigurable fixtures. This study proposes a comparative design procedure for reconfigurable assembly fixtures that can adapt to manufacturing system characteristics by using efficiency metrics. In this study, a theoretical analysis based on manufacturing systems is presented to establish efficiency metrics. Later, these metrics are utilized in a design procedure that offers guidance and determines the efficiency of fixtures in conceptual and detailed design stages. Finally, an experimental verification is presented.
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| 9. |
- Eynian, Mahdi, 1980-
(författare)
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Prediction of vibration frequencies in milling using modified Nyquist method
- 2015
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Ingår i: CIRP - Journal of Manufacturing Science and Technology. - : Elsevier. - 1755-5817 .- 1878-0016. ; 11:November, s. 73-81
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Tidskriftsartikel (refereegranskat)abstract
- Study of the vibration frequencies at different cutting conditions is an alternative to the use of impact hammer test for identification of natural frequencies of the machining structure and calculation of stability lobe diagrams. Vibration frequencies not only depend on the natural frequencies of the structure, but also they are dependent on the spindle speed, damping ratio of the structure and the depth of cut. Ignoring these additional parameters would lead to errors in identification of the natural frequencies of the system and considerable deviation of the calculated stability lobe diagrams from actual cutting tests. In this study modified Nyquist method is used to investigate the effects of spindle speed, depth of cut and damping ratio of the structure on vibration frequencies. The quality of frequency prediction is compared to linear and nonlinear time domain simulations and machining experiments.
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| 10. |
- Farooqui, Ashfaq Hussain, 1990, et al.
(författare)
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From factory floor to process models: A data gathering approach to generate, transform, and visualize manufacturing processes
- 2019
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Ingår i: CIRP Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 24, s. 6-16
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Forskningsöversikt (refereegranskat)abstract
- The need for tools to help guide decision making is growing within the manufacturing industry. The analysis performed by these tools will help operators and engineers to understand the behaviour of the manufacturing stations better and thereby take data-driven decisions to improve them. The tools use techniques borrowed from fields such as Data Analytics, BigData, Predictive Modelling, and Machine Learning. However, to be able to use these tools efficiently, data from the factory floor is required as input. This data needs to be extracted from two sources, the PLCs, and the robots. In practice, methods to extract usable data from robots are rather scarce. The present work describes an approach to capture data from robots, which can be applied to both legacy and current state-of-the-art manufacturing systems. The described approach is developed using Sequence Planner - a tool for modelling and analyzing production systems - and is currently implemented at an automotive company as a pilot project to visualize and examine the ongoing process. By exploiting the robot code structure, robot actions are converted to event streams that are abstracted into operations. We then demonstrate the applicability of the resulting operations, by visualizing the ongoing process in real-time as Gantt charts, that support the operators performing maintenance. And, the data is also analyzed off-line using process mining techniques to create a general model that describes the underlying behaviour existing in the manufacturing station. Such models are used to derive insights about relationships between different operations, and also between resources.
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