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In order to create a machining line layout that supports the principles of lean a systematic approach is needed to ensure that a wide range of factors are taken into consideration. Despite this, many companies today design new layouts mainly considering delivery times of machines and equipment, and available space in the factory. A combined literature and case study has aimed to identify the most important factors in a lean line layout and a supporting structure to apply these in the design or redesign of automated machining lines. Highly automated machining environments mainly distinguish themselves from the more thoroughly studied area of assembly line layouts in two ways. Primarily, automated machining lines separate the operator from the actual processing, making line balancing and productivity less dependent on the workstation design around the operator. Secondly, automated machining lines often involve a higher level of complexity, leading to a more comprehensive work load, requiring longer training times but also offering less repetitive assignments. Automation offers improved productivity, quality and ergonomics, but if the acquisition and allocation of automation is not substantiated by a well-developed strategy, automation risks contradicting lean principles by creating a more complex, rigid layout that places the machines in the center instead of the workers. Factors that are important in the design of the typically less automated assembly lines, such as minimizing the walking distance of the operator and rotating stations to provide meaningful work assignments, must in an automated machining environment give way to factors like visualization, material flow and maintenance. Visualizing a factory helps operators and managers learn and understand the factory better. Problems can be detected and corrected faster and disturbances in production can thus be reduced. A good material flow is straight with no intersecting flows, triggered by downstream demand and reduces unnecessary buffers and WIP that bind up capital and consume space. Finally, since the machines rather than the operators produce, a good maintenance is required to avoid unplanned stops. The value of teamwork and humans in production which are strongly advocated within lean remain important also in automated machining lines but acquires a new content compared to assembly lines. Teamwork in automated machining environments occur within a group of lines rather than in a single line and it is a major factor when it comes to competence development, production planning and worker satisfaction. While teamwork in assembly lines works to balance the production flow within the line, teamwork in automated machining lines has little or no effect on the line balancing. However, joint efforts in setups and in case of machine failures or worker absence help increasing productivity, and potentially smooth the production at the plant in its entirety. The empirical studies showed that there is no standardized way of working with machining line layout design and redesign, and factors considered were often coincidental and dependent on the functions and priorities of the participants at different layout meeting. To ensure that all factors are taken into consideration a supporting tool where the most important factors were divided into ten categories was developed. Layouts are evaluated and rated on one category at a time to support a systematic way of working. Ongoing discussions, adjustments and improvements to better comply with the factors are encouraged.

The ultimate goal in the manufacturing of a part is to achieve an economic production plan with precision and accuracy in the first attempt at machining. A physics-based comprehensive modeling of the machining processes is a fundamental requirement in identifying optimal cutting conditions which result in high productivity rates without violating accuracy throughout the part production process. This thesis presents generalized virtual simulation and optimization strategies to predict and optimize performance of milling processes up to 3-axis. Computationally efficient mathematical models are introduced to predict milling process state variables such as chip load, force, torque, and cutting edge engagement at discrete cutter locations. Process states are expressed explicitly as a function of helical cutting edge - part engagement, cutting coefficient and feedrate. Cutters with arbitrary geometries are modeled parametrically, and the intersection of helical cutting edges with workpiece features are evaluated either analytically or numerically depending on geometric complexity. The dynamics of generalized milling operations are modeled and the stability of the process is predicted using both time and frequency domain based models. These algorithms enable rapid simulation of milling operations in a virtual environment as the part features vary. In an effort to reduce machining time, a constraint-based optimization scheme is proposed to maximize the material removal rate by optimally selecting the depth of cut, width of cut, spindle speed and feedrate. A variety of user defined constraints such as maximum tool deflection, torque/power demand, and chatter stability are taken into consideration. Two alternative optimization strategies are presented: pre-process optimization provides allowable depth and width of cut during part programming at the computer aided manufacturing stage using chatter constraint, whereas the post-process optimization tunes only feedrate and spindle speed of an existing part program to maximize productivity without violating physical constraints of the process. Optimized feedrates are filtered by considering machine tool axes limitations and the algorithms are tested in machining various industrial parts. The thesis contributed to the development of a novel 3-axis Virtual Milling System that has been deployed to the manufacturing industry.

This thesis presents the research work carried out in an experimental study on High Speed Milling and a predictive force model. The Oxley??s machining theory [36] that can be considered a purely theoretical approach, which has not yet been applied to the high speed milling process is used to model this process in order to predict the cutting forces. An experimental programme was carried out in order to study and understand the high speed milling process and to collect force data for machining of AISI 1020 plain carbon steel at speeds from 250 to 500m/min, feed rates 0.025 to 0.075mm/tooth and 0.5 and 0.8mm depths of cut, using three different tool configurations with different nose radii. The model developed by Young [5] using the Oxley??s machining theory, for conventional milling, was first applied to the high speed milling operation. The force predictions were satisfactory compared to the measured forces. Using this as the basis, a theoretical model was developed to predict the cutting forces in high speed milling. A smaller chip element was considered in applying the machining theory to satisfy the assumption of two dimensional deformation in the machining theory. Using the flow stress properties for plain carbon steels obtained by Oxley and his co-workers, the cutting force components: tangential, radial and vertical, were predicted with the new developed model for AISI 1020 steel for the same cutting conditions used in the experiment. The model was able to accurately predict the tangential force, while the other two components showed a good agreement with the experimental forces. Then the model was verified using two other materials namely, AISI 1045 plain carbon steel and AISI 4140 alloy steel. The alloy steel was used in both the states, virgin and hardened (heat treated) for the experiment. The comparison of predictions with experimental forces showed good results for these additional two materials. From the results obtained, it is concluded that the developed model can be used to predict the tangential cutting force accurately, while predicting the other force components with a favourable accuracy.

This thesis presents the research work carried out in an experimental study on High Speed Milling and a predictive force model. The Oxley??s machining theory [36] that can be considered a purely theoretical approach, which has not yet been applied to the high speed milling process is used to model this process in order to predict the cutting forces. An experimental programme was carried out in order to study and understand the high speed milling process and to collect force data for machining of AISI 1020 plain carbon steel at speeds from 250 to 500m/min, feed rates 0.025 to 0.075mm/tooth and 0.5 and 0.8mm depths of cut, using three different tool configurations with different nose radii. The model developed by Young [5] using the Oxley??s machining theory, for conventional milling, was first applied to the high speed milling operation. The force predictions were satisfactory compared to the measured forces. Using this as the basis, a theoretical model was developed to predict the cutting forces in high speed milling. A smaller chip element was considered in applying the machining theory to satisfy the assumption of two dimensional deformation in the machining theory. Using the flow stress properties for plain carbon steels obtained by Oxley and his co-workers, the cutting force components: tangential, radial and vertical, were predicted with the new developed model for AISI 1020 steel for the same cutting conditions used in the experiment. The model was able to accurately predict the tangential force, while the other two components showed a good agreement with the experimental forces. Then the model was verified using two other materials namely, AISI 1045 plain carbon steel and AISI 4140 alloy steel. The alloy steel was used in both the states, virgin and hardened (heat treated) for the experiment. The comparison of predictions with experimental forces showed good results for these additional two materials. From the results obtained, it is concluded that the developed model can be used to predict the tangential cutting force accurately, while predicting the other force components with a favourable accuracy.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 9, 2009) Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [127]-134).

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 108-112). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph.D.). / Written for the Dept. of Mechanical Engineering. Title from title page of PDF (viewed 2009/06/10). Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 134-139). Also available on the Internet.