1. |
- Agic, Adnan, 1967-
(author)
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Analysis of entry phase in intermittent machining
- 2018
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Licentiate thesis (other academic/artistic)abstract
- Cutting forces and vibrations are essential parameters in the assessment of a cutting process. As the energy consumption in the machining process is directly affected by the magnitude of the cutting forces it is of vital importance to design cutting edges and select process conditions that will maintain high tool performance through reduced energy consumption. The vibrations are often the cause of poor results in terms of accuracy, low reliability due to sudden failures and bad environmental conditions caused by noise. The goal of this work is to find out how the cutting edge and cutting conditions affect the entry conditions of the machining operation. This is done utilizing experimental methods and appropriate theoretical approaches applied to the cutting forces and vibrations. The research was carried out through three main studies beginning with a force build-up analysis of the cutting edge entry into the workpiece in intermittent turning. This was followed by a second study, concentrated on modelling of the entry phase which has been explored through experiments and theory developed in the first study. The third part was focused on the influence of the radial depth of cut upon the entry of cutting edge into the workpiece in a face milling application. The methodology for the identification of unfavourable cutting conditions is also explained herein. Important insights into the force build-up process help addressing the correlation between the cutting geometries and the rise time of the cutting force. The influence of the nose radius for a given cutting tool and workpiece configuration during the initial entry is revealed. The critical angle i.e. the position of the face milling cutter that results in unfavourable entry conditions has been explained emphasizing the importance of the selection of cutting conditions. Finally, the theoretical methods utilized for the evaluation of the role of cutting edge geometry within entry phase dynamics has been explored. This has revealed the trends that are of interest for selection of cutting conditions and cutting edge design.
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2. |
- Agic, Adnan, 1967-, et al.
(author)
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Dynamic effects on cutting forces with highly positive versus highly negative cutting edge geometries
- 2019
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In: International Journal on Interactive Design and Manufacturing. - : Springer Science and Business Media LLC. - 1955-2513 .- 1955-2505. ; 13:2, s. 557-565
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Journal article (peer-reviewed)abstract
- Understanding the influence of the cutting edge geometry on the development of cutting forces during the milling process is of high importance in order to predict the mechanical loads on the cutting edge as well as the dynamic behavior on the milling tool. The work conducted in this study involves the force development over the entire engagement of a flute in milling, from peak force during the entry phase until the exit phase. The results show a significant difference in the behavior of the cutting process for a highly positive versus a highly negative cutting edge geometry. The negative edge geometry gives rise to larger force magnitudes and very similar developments of the tangential and radial cutting force. The positive cutting edge geometry produces considerably different developments of the tangential and radial cutting force. In case of positive cutting edge geometry, the radial cutting force increases while the uncut chip thickness decreases directly after the entry phase; reaching the peak value after a certain delay. The radial force fluctuation is significantly higher for the positive cutting edge geometry. The understanding of such behavior is important for modelling of the milling process, the design of the cutting edge and the interactive design of digital applications for the selection of the cutting parameters.
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3. |
- Agic, Adnan, 1967-
(author)
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Edge Geometry Effects on Entry Phase by Forces and Vibrations
- 2020
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Doctoral thesis (other academic/artistic)abstract
- Intermittent machining is in general strongly related to the large impacts in the entry phase and related vibrations. The influence of the impact forces and vibrations on the cutting process is dependent on workpiece material, structural properties of the tool-workpiece system, cutting edge geometries and cutting parameters. Cutting forces adopt generally a periodic behaviour that gives rise to forced vibrations. In addition, self-induced vibrations may arise because of lowrigidity and insufficient damping in the tool-workpiece system at specific cutting parameters. The ability of the cutting tool to carry the loads during the entry phase and minimize the vibrations is often the key parameter for an effective machining operation.This research work is based on the experiments, analytical studies and modelling. It was carried out through six main studies beginning with a force build-up analysis of the cutting edge entry into the workpiece in intermittent turning. This was followed by a second study, concentrated on modelling of the entry phase which has partly been explored through experiments and theory developed in the first study.The third part was focused on the influence of the radial depth of cut upon the entry of the cutting edge into the workpiece in a face milling application. The methodology for the identification of unfavourable radial depth of cut is also addressed herein. Next, effects of the cutting edge on the vibrations in an end milling application were investigated. This study was related to a contouring operation with the maximum chip thickness in the entry phase when machining steel, ISO P material.The results of this work provide some general recommendations when milling this type of workpiece material. After that, the focus was set on the dynamic cutting forces in milling. The force developments over a tooth engagement in milling showed to be strongly dependent on the cutting edge geometry. A significant difference between highly positive versus highly negative geometry was found.The implication of this phenomena on the stress state in the cutting edge and some practical issues were analysed. Finally, the role of the helix angle on the dynamic response of a workpiece was investigated. The modelling technique using force simulation and computation of the dynamic response by means of modal analysis was presented. Extensive experimental work was conducted to compare the modelling and experimentally obtained results. The modelling results showed a similar trend as the experimental results. The influence of helix angle on the cutting forces and the dynamic response was explained in detail.The research conducted in this work contributes to the deeper understanding of the influence of the cutting edge geometry and the cutting parameters on the force build up process during the entry phase. The presented studies investigate the force magnitudes, force rates and dynamic behaviour of the tools and workpieces when machining at the challenging entry conditions. The methodologies applied are focused on the physical quantities as forces and vibrations rather than the experimental studies that evaluate tool life. The methods and results of the research work are of great interest for the design of the cutting tools and optimization of the cutting processes.
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4. |
- Agic, Adnan, 1967-, et al.
(author)
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Experimental analysis of cutting edge effects on vibrations in end milling
- 2019
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In: CIRP - Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 24, s. 66-74
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Journal article (peer-reviewed)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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5. |
- Agic, Adnan, et al.
(author)
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Influence of radial depth of cut on dynamics of face milling application
- 2016
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In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings. - Lund : Swedish Production Academy. ; , s. 1-9
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Conference paper (peer-reviewed)abstract
- The choice of milling cutter geometry and appropriate cutting data for certain milling application is of vital importance for successful machining results. Unfavourable selection of cutting conditions might give rise to high load impacts that cause severe cutting edge damage. The radial depth of cut in combination with milling cutter geometry might under some circumstances give unfavourable entry conditions in terms of cutting forces and vibration amplitudes. This phenomenon originates from the geometrical features that affect the rise time of the cutting edge engagement into work piece at different radial depths of cut. As the radial depth of cut is often an important parameter, particularly when machining difficult to cut materials, it is important to explore the driving mechanism behind vibrations generation. In this study, acceleration of the work piece is measured for different radial depths of cut and cutting edge geometries. The influence of the radial depth of cut on the dynamical behaviour is evaluated in time and frequency domains. The results for different radial depths of cut and cutting geometries are quantified using root mean square value of acceleration. The outcome of this research study can be used both for the better cutting data recommendations and improved tool design.
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6. |
- Agic, Adnan, 1967-, et al.
(author)
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Influence of radial depth of cut on entry conditions and dynamics in face milling application
- 2017
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In: Journal of Superhard Materials. - New York : Allerton Press. - 1063-4576 .- 1934-9408. ; 39:4, s. 259-270
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Journal article (peer-reviewed)abstract
- The choice of milling cutter geometry and appropriate cutting data for certain milling application is of vital importance for successful machining results. Unfavorable selection of cutting conditions might give rise to high load impacts that cause severe cutting edge damage. Under some circumstances the radial depth of cut in combination with milling cutter geometry might give unfavorable entry conditions in terms of cutting forces and vibration amplitudes. This phenomenon is originated from the geometrical features that affect the rise time of the cutting edge engagement into workpiece at different radial depths of cut. As the radial depth of cut is often an important parameter, particularly when machining difficult-to-cut materials, it is important to explore the driving mechanism behind vibrations generation. In this study, acceleration of the workpiece is measured for different radial depths of cut and cutting edge geometries. The influence of the radial depth of cut on the dynamical behavior is evaluated in time and frequency domains. The results for different radial depths of cut and cutting geometries are quantified using the root mean square value of acceleration. The outcome of this research study can be used both for the better cutting data recommendations and improved tool design.
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7. |
- Anderberg, Staffan, 1981-
(author)
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A study of process planning for metal cutting
- 2009
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Licentiate thesis (other academic/artistic)abstract
- Process planning as a function for competitiveness is often neglected. However, as an intermediary between product development and manufacturing, it holds a key function in transforming product specifications and requirements into a producible process plan. Demands and requirements should be met concurrently as manufacturing costs and lead times are minimised. The focus of this thesis is the act of process planning, where the use of better methodologies, computer-aids and performance measurements are essential parts. Since process planning has the function of transforming demands and requirements, changing customer and regulative requirements are vital to regard. Since environmentally benign products and production increases in importance, the research presented in this thesis includes a CNC machining cost model, which relates machining costs to energy consumption. The presented results in this thesis are based on quantitative and qualitative studies in the metal working industry. This thesis has contributed to an enhanced understanding of process planning to achieve better performance and important areas for improvements. Despite a 50 year history of computerised process planning aids, few of these are used in the industry, where manual process planning activities are more common. Process planning aids should be developed around the process planner so that non-value adding activities, such as information management and documentation are minimised in order to allow more resources for value adding activities, such as decision making. This thesis presents a study of systematic process planning in relation to perceived efficiency. This correlation could however not be verified, which opens up for further studies of other possible explanations for process planning efficiency. Process planning improvements in the industry are difficult to make, since there is little focus on process planning activities and limited knowledge about actual performance hereof. This means that measures taken regarding process planning development are difficult to verify.
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8. |
- Anderberg, Staffan, 1981-, et al.
(author)
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A survey of metal working companies’ readiness for process planning performance measurements
- 2009
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In: IEEE International Conference on Industrial Engineering and Engineering Management, IEEM 8-11 sep, 2009, Hong-Kong. - 9781424448708 ; , s. 1910-1914
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Conference paper (peer-reviewed)abstract
- The paper presents an investigation regarding the potential and the readiness for implementing performance indicators and performance measurement systems of the process planning work for metal working companies. The paper is based on a questionnaire survey distributed to process planners in the Swedish metal working industry. The main outcome of the investigation is a foundation for understanding the implementation of performance measures of the process planning work for CNC machining. The survey revealed a few strengths and short comings in the studied companies.
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9. |
- Anderberg, Staffan, 1981-, et al.
(author)
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CNC machining process planning productivity – a qualitative survey
- 2009
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In: Proceedings of <em>The International</em> 3'rd <em>Swedish Production Symposium</em>, SPS 09. - 9789163360060 ; , s. 228-235
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Conference paper (peer-reviewed)abstract
- Process planning is the link between design and manufacturing and consequently an important function, since it influences many of the company objectives. However, many companies have little knowledge about their process planning function and the efficiency is thus not optimal. The paper focuses on the automation level of process planning as a mean to improve process planning efficiency. Six CNC machining companies was interviewed and accordingly analysed through a five dimensional automation level model to understand their process planning work. The main findings are that the automation level is low and concurrent engineering is lacking in many of the investigated companies.
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10. |
- Anderberg, Staffan, 1981-, et al.
(author)
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Energy and Cost Efficiency in CNC Machining from a Process Planning Perspective
- 2011
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In: 9th Global Conference on Sustainable Manufacturing. - 9783798323759 ; , s. 383-389
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Conference paper (peer-reviewed)abstract
- The role of process planning as an enabler for cost efficient and environmentally benign CNC machining is investigated in the paper. Specific energy is used as the principal indicator of energy efficient machining and different methods to calculate and estimate this is exemplified and discussed. The interrelation between process planning decisions and production outcome is sketched and process capability can be considered as one factor of green machining. A correlation between total machining cost and total energy use was shown for an experimental case. However, to generalise conclusions, the importance of having reliable data during process planning to make effective decisions should not be underestimated.
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11. |
- Anderberg, Staffan, 1981-, et al.
(author)
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Impact of energy efficiency on computernumerically controlled machining
- 2010
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In: Proceedings of the Institution of mechanical engineers. Part B, journal of engineering manufacture. - London : Professional Engineering Publishing. - 0954-4054 .- 2041-2975. ; 224:B4, s. 531-541
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Journal article (peer-reviewed)abstract
- Increasing environmental demands from governmental bodies and customers stress the importance of companies improving their environmental performance. The research presented here shows that productivity and cost efficiency improvements can be achieved alongside energy savings in a computer numerically controlled machining environment. This improves the profitability of the companies, but also leads them towards more sustainable and environmentally aware manufacturing; the relationship between machining parameters, machining costs, and energy consumption is evaluated. From this perspective, it is important that production planners etc. understand the methodological possibilities for improvements in cost and energy efficiency. The current research is based on a machining cost model and experiments where energy consumption and tool wear were monitored.
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12. |
- Anderberg, Staffan, 1981-, et al.
(author)
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Process planning for cnc machining of swedish subcontractors : A web survey
- 2014
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In: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 17, s. 732-737
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Journal article (peer-reviewed)abstract
- Process planning of CNC machining is critical to ensure cost, time and quality parameters of manufacturing operations. At the heart of process planning is, typically the process planner, who must make a multitude of decisions regarding machines, cutting strategies, tools and process parameters etc. Today there are a number of different tools and methods available to aid the process planner. This paper explores today’s industrial use of some of these aids and outlinespotential underlying reasons for the current state. The empirical data is based on a questionnaire survey of Swedish CNC machining sub-contractors. The main conclusion is that despite a long history of development of various aids (CAD/CAM, PLM standards etc.) there is still a large proportion of the industry, which has not yet adopted these aids. By the responding companies 32% do not use any CAM system and only 2% use a PLM system. On the other side of the spectrum is a group of 25% that uses CAM in 75% or more of their planned products. The learning from this survey can be used to better understand the industrial needs and focus research and development efforts.
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13. |
- Anderberg, Staffan, 1981-, et al.
(author)
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Production preparation methodology in Swedish metal working industry - a State of the Art investigation
- 2008
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In: Swedish Production Symposium, Stockholm 18-20 November 2008. Proceedings. - Stockholm : The Swedish Production Academy. ; , s. 443-450
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Conference paper (other academic/artistic)abstract
- This article presents a brief state of the art in the Swedish metal working industry regarding the production preparation process for the machine centre. The article is based on a relationship model from which a questionnaire was developed. The model incorporates the perceived preparation process efficiency, the amount of systematic preparation work, in relation to the companies’ premises as possible causes. The investigation is based on a general hypothesis that a more systematic approach in the preparation process leads to higher preparation process efficiency. This hypothesis was supplemented by two more hypotheses and additional analyses to create an understanding of the situation. The main finding in this investigation is that there appear to be no relationship between increased ystematic preparation work and perception of higher preparation efficiency. The investigation also indicates that many metal working companies have little knowledge about the performance of their preparation process and that there is an efficiency improvement potential of nearly 30%.
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14. |
- Beno, Tomas, et al.
(author)
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Green machining : improving the bottom line
- 2009
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Conference paper (other academic/artistic)abstract
- The aim of this paper is to present how Green machining can be established in the metal working industry for taking immediate actions towards a more environmental friendly manufacturing, but also to address areas for research in order to advance towards a more sustainable manufacturing industry. An often overlooked approach is to use the knowledge about the specific cutting energy and its dependency upon machining parameters in order to establish a machining strategy that leads towards a more energy efficient production, but also contributes to increased productivity and thereby improving the bottom line as well. The paper has a production preparation perspective and thus presents the areas where a green machining strategy is applicable.
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19. |
- Beno, Tomas, et al.
(author)
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Measurement of cutting edge temperature in drilling
- 2012
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In: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 3, s. 531-536
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Journal article (peer-reviewed)abstract
- In this paper a methodology is described to conduct temperature measurement on the cutting edges and the clearance faces on twist drills using a fibre optic two color pyrometer. Two measuring positions of the fibre were used in order to determine the temperature at two different locations, centre and outer corner of the drill. The measurements were carried out on a stationary work piece and a rotating drill. The work piece materials ranged from tool steel, aged Inconel 718, Ti6-4 to carbon epoxy fibre composite. All experiments were conducted in dry machining conditions.© 2012 The Authors.
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20. |
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21. |
- Beno, Tomas, et al.
(author)
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The Use of Machine Tool Internal Encoders as Sensors in a Process Monitoring System
- 2013
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In: International Journal of Automation Technology. - : Fuji Technology Press Ltd.. - 1881-7629 .- 1883-8022. ; 7:4, s. 410-417
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Journal article (peer-reviewed)abstract
- Tool wear in machining changes the geometry of the cutting edges, which affects the direction and amplitudes of the cutting force components and the dynamics in the machining process. These changes in the forces and dynamics are picked up by the internal encoders and thus can be used for monitoring of changes in process conditions. This paper presents an approach for the monitoring of a multi-tooth milling process. The method is based on the direct measurement of the output from the position encoders available in the machine tool and the application of advanced signal analysis methods.The paper investigates repeatability of the developed method and discusses how to implement this in a process monitoring and control system. The results of this work show that various signal features which are correlated with tool wear can be extracted from the first few oscillating components, representing the low-frequency components, of the machine axes velocity signatures. The responses from the position encoders exhibit good repeatability, especially short term repeatability while the long-term repeatability is more unreliable.
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22. |
- Bonilla Hernández, Ana Esther
(author)
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Analysis and direct optimization of cutting tool utilization in CAM
- 2015
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Licentiate thesis (other academic/artistic)abstract
- The search for increased productivity and cost reduction in machining can be interpreted as the desire to increase the material removal rate, MRR, and maximize the cutting tool utilization. The CNC process is complex and involves numerous limitations and parameters, ranging from tolerances to machinability. A well-managed preparation process creates the foundations for achieving a reduction in manufacturing errors and machining time. Along the preparation process of the NC-program, two different studies have been conducted and are presented in this thesis. One study examined the CAM programming preparation process from the Lean perspective. The other study includes an evaluation of how the cutting tools are used in terms of MRR and tool utilization.The material removal rate is defined as the product of three variables, namely the cutting speed, the feed and the depth of cut, which all constitute the cutting data. Tool life is the amount of time that a cutting tool can be used and is mainly dependent on the same variables. Two different combinations of cutting data might provide the same MRR, however the tool life will be different. Thereby the difficulty is to select the cutting data to maximize both MRR and cutting tool utilization. A model for the analysis and efficient selection of cutting data for maximal MRR and maximal tool utilization has been developed and is presented. The presented model shortens the time dedicated to the optimized cutting data selection and the needed iterations along the program development.
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23. |
- Bonilla Hernández, Ana Esther, et al.
(author)
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Analysis of Tool Utilization from Material Removal Rate Perspective
- 2015
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In: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 29, s. 109-113
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Journal article (peer-reviewed)abstract
- An end of life strategy algorithm has been used to study a CNC program to evaluate how the cutting inserts are used in terms of their full utilization. Utilized tool life (UTL) and remaining tool life (RTL) were used to evaluate if the insert has been used to its limits of expected tool life, or contributing to an accumulated tool waste. It is demonstrated that possible means to improvement exists to increase the material removal rate (MRR), thereby using the insert until its remaining tool life is as close to zero as possible. It was frequently found that inserts were used well below their maximum performance with respect to cutting velocity.
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24. |
- Bonilla Hernández, Ana Esther, et al.
(author)
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Energy and Cost Estimation of a Feature-based Machining Operation on HRSA
- 2017
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In: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 61:Supplement C, s. 511-516
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Journal article (peer-reviewed)abstract
- Forward-looking manufacturing companies aim for sustainable production with low environmental footprint. This is true also for aerospace engine-makers, although their environmental impact mostly occurs during the use-phase of their products. Materials, such as Nickel alloys, are used for special applications where other materials will not withstand tough working conditions in terms of pressure and temperature. Heat Resistant Super Alloys are, however, considered difficult to machine and cutting tools will wear off rapidly. In this paper, a simple way to estimate the energy required, the cost and environmental footprint to produce a work piece using standard engineering software is presented. The results show that for a hypothetical 3 tonne work piece, Inconel 718 will be considerably cheaper and require less water but will require more energy, and has considerably larger CO2 footprint than Waspaloy.
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25. |
- Bonilla Hernández, Ana Esther, et al.
(author)
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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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In: CIRP - Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 13, s. 46-50
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Journal article (peer-reviewed)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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