April Bryan

Assembly System Reconfiguration Planning

Decreasing product life cycles and reduced product development times have led to a need for new strategies for coping with the rapid rate of product family design changes. In this paper, assembly system reconfiguration planning (ASRP) is introduced as a method for cost effectively designing several generations of assembly systems in order to produce a product family that gradually evolves over time. In the ASRP approach, the possible assembly systems for each generation are first considered and then the sequence of assembly system configurations that minimize the life cycle cost of the process are selected. A nonlinear integer optimization formulation is developed for finding the cost minimizing assembly system reconfiguration plan using the ASRP approach. Dynamic programming and genetic algorithm are used to solve the optimization problem. Simulation results indicate that the ASRP approach leads to the minimum life cycle costs of the assembly system, and the relative cost of reconfiguration and production have an impact on the assembly system reconfiguration plan selected. Comparison of the results of the dynamic program and genetic algorithm indicate that the dynamic program is more computationally efficient for small problems and genetic algorithm is preferred for larger problems.

Volumetric Flank Wear Characterization for Titanium Milling Insert Tools

Machining wear models are useful for the prediction of tool life and the estimation of machining productivity. Existing wear models relate the cutting parameters of feed, speed, and depth of cut to tool wear. The tool wear is often reported as changes in flank width or crater depth. However, these one-dimensional wear measurements do not fully characterize the tool condition when tools wear by other types of wear such as notching, chipping, and adhesion. This is especially true when machining difficult-to-machine materials such as titanium. This paper proposes another approach for characterizing tool wear. It is based on taking measurements of the retained volume of the cutting tool. The new wear characterization approach is used to demonstrate the progression of volumetric wear in titanium milling.Copyright

Concurrent design of product families and assembly systems

In order to gain competitive advantage, manufacturers require cost effective methods for developing a variety of products within short time periods. Product families, reconfigurable assembly systems and concurrent engineering are frequently used to achieve this desired cost effective and rapid supply of product variety. The independent development of methodologies for product family design and assembly system design has led to a sequential approach to the design of product families and assembly systems. However, the designs of product families and assembly systems are interdependent and efficiencies can be gained through their concurrent design. There are no quantitative concurrent engineering techniques that address the problem of the concurrent design of product families and assembly systems. In this paper, a non-linear integer programming formulation for the concurrent design of a product family and assembly system is introduced. The problem is solved with a genetic algorithm. An example is used to demonstrate the advantage of the concurrent approach to product family and assembly system design over the existing sequential methodology.Copyright

Assembly System Reconfiguration Planning Using Genetic Algorithm

Due to increased competition, the rate at which manufacturers introduce new product families to the market is increasing. However, the cost of changing manufacturing facilities to produce new product families can outweigh the benefits obtained from increased revenue. Reconfigurable Manufacturing Systems (RMSs) have been proposed as a cost effective strategy for manufacturing product families. Although methods for measuring RMS scalability and convertibility exist, there is a lack of methods for obtaining reconfiguration plans for assembly systems. This paper introduces assembly system reconfiguration planning (ASRP) as method to obtain reconfiguration plans for assembly systems. A genetic algorithm is developed for solving the ASRP problem.© 2008 ASME

Evaluating Lifelong Learning

One of the required ABET outcomes is “a recognition of the need for, and an ability to engage in lifelong learning.” Although students must demonstrate this recognition and ability at graduation, data from alumni can strengthen a program’s assertion that its graduates actually engage in lifelong learning. Several strategies for demonstrating lifelong learning are presented and discussed. In addition, a case study from the Mechanical Engineering Department at Rose-Hulman Institute of Technology is presented. For the case study, several assessment instruments were used: an alumni survey, employer focus groups, an Advisory Board survey, and feedback from senior students. Each component will be discussed, results will be presented, and conclusions will be drawn. The alumni survey was made via the internet. The 760 respondents included graduates from the 1940s through the 2000s. Respondents were asked to indicate the number of additional courses or workshops that they had taken and whether or not they had received any additional degrees. Furthermore, respondents were asked to rate the importance of lifelong learning to their current job. In addition, they were asked to rate how well Rose had prepared them for lifelong learning. Employer perspective was gained through focus groups and the advisory board. Companies who were present at career fairs were asked to answer questions about Rose graduates in general. The ME Advisory Board contains members from institutions who are major employers of our graduates. Advisory board members gave feedback based on their knowledge of graduates’ performances. As in the alumni survey, both groups were asked to rate the importance of lifelong learning, along with how well Rose prepared them. Finally graduating seniors were asked to rate how important they felt lifelong learning would be in their careers. In addition, they were asked how well prepared they thought they were. All groups surveyed rated the ability to continue to learn and educate one’s self as being important, and all groups felt that RHIT graduates met the required standard.Copyright

Geometric Error Assessment of a Nanomechanical Drill

Manufacturability of micro and nano systems has gained importance with the advent of microelectromechanical systems (MEMS). Whereas the manufacturability of macro systems has been a widely researched subject, the behavior of MEMS devices in large scale manufacturing operations is virtually an unexplored field. Therefore, in order to predict resulting product characteristics, theories developed for macro-scale manufacturing are currently being extended to micro-systems. This research employs computer aided engineering (CAE) tools in the determination of the final dimensional quality of a drilled hole created by a nano-drill. In order to obtain a valid prediction of the drilled-hole dimensions, an adequate knowledge of the processes occurring during nano drilling and the factors affecting these processes are necessary. A complete analysis requires consideration of the kinematic, static and dynamic factors that contribute to the error in the drill tip. In this paper, only the kinematic errors that affect the hole geometric quality are considered. The causes of these kinematic errors and their effect on the variation of the drilled hole are also investigated. The resulting hole size will be considered to be the result of the “stack-up” of the errors in the tool.Copyright

Methodology for Solving the Assembly System Reconfiguration Planning Problem

The need to cost effectively introduce new generations of product families within ever decreasing time frames have led manufacturers to seek product development strategies with a multigenerational outlook. Co-evolution of product families and assembly systems is a methodology that leads to the simultaneous design of several generations of product families and reconfigurable assembly systems that optimize life cycle costs. Two strategies that are necessary for the implementation of the co-evolution of product families and assembly systems methodology are: (1) The concurrent design of product families and assembly systems and (2) Assembly system reconfiguration planning (ASRP). ASRP is used for the determination of the assembly system reconfiguration plans that minimize the cost of producing several generations of product families. More specifically, the objective of ASRP is to minimize the net present cost of producing successive generations of products. This paper introduces a method for finding optimum solutions to the ASRP problem. The solution methodology involves the generation of a staged network of assembly system plans for all the generations that the product family is expected to be produced. Each stage in the network represents a generation that the product family is produced, while each state within a stage represents a potential assembly system configuration. A novel algorithm for generating the states (i.e. assembly system configurations) within each generation is also introduced. A dynamic program is used to find the cost minimizing path through the network. An example is used to demonstrate the implementation of the ASRP methodology.Copyright