Research in the LMAS is concerned with the analysis and improvement of manufacturing processes and the development of tools to analyze sustainability. Research projects address: metrics and analytical tools for assessing the impact of processes including design for sustainability, systems and enterprises, modeling sustainable, environmentally-conscious manufacturing processes and systems, green supply chains, manufacturing technology for reduced impact, manufacturing technology for producing advanced energy sources or storage cleantech and sustainable products and systems. Specifically, research is focused on minimizing/removing contaminants and machining defects during manufacture, improving the precision and repeatability of chemical mechanical polishing, green machine tools and processes, sustainable packaging, and modeling sustainable, environmentally-conscious manufacturing processes and systems. The main lab groups within the LMAS are Precision Manufacturing, Green Engineering, and SMP (the Sustainable Manufacturing Partnership). An earlier research effort CODEF (Consortium on Deburring and Edge Finishing) has completed its work. Each of these groups conduct research with an eye to sustainability, and maintain a common goal of reducing waste (time, energy, materials).
This paper presents an investigation on micro-burr formation in machining. Micro cutting is compared with conventional cutting in terms of cutting process characteristics and cutting conditions. An acceptable range of cutting conditions for micro cutting has been determined by extrapolating the conditions for conventional cutting and experimental verification. With cutting conditions determined, a series of experiments was conducted to investigate burr formation and tool life. Herein, tool life is defined as the number of holes created before a catastrophic increase in burr height occurs. Based on experimental results, contour charts for predicting burr formation as well as tool life are developed to minimize burr formation and to improve tool life.
The derivation and implementation of an algorithm that calculates exit order sequence (EOS) as a planar milling burr prediction tool is presented. EOS expresses the orientation of a cutter relative to the workpiece in terms of the exit order of three points describing the major and minor cutting edges. EOS calculations along the contours of a CAD model are based upon an instantaneous, Cartesian frame of reference centered on the tool spindle axis and oriented in the feed direction. The scheme provides accurate and robust EOS calculations and introduces a “worst-case” approach to select a unique EOS from overlapping tool exit conditions.
Accurate models of twist drills are needed for Finite Element simulations of the drilling process. Existing drill designing methods rely extensively on discretized analytical equations to describe the drill and different sets of equations need to be formulated as the drill design changes. This paper presents a method to create accurate models of two-flute conical twist drills using solid-modeling techniques which addresses some of these shortcomings. Boolean operations are used to mimic the drill manufacturing steps and generate the fully designed drill. The drills generated by this method have been used in Finite Element simulations to study the effect of drill point geometry on burr formation in drilling.
This study is an evaluation of the use and supply of compressed air, which is one of the most expensive energy sources in manufacturing, at Ford Motor Company’s Livonia (Mich.) Transmission Plant. The aim of the study is to make recommendations to improve environmental and economic efficiency in future facilities. This paper presents a quantitative analysis of three compressed air supply patterns—plant air, point of use (POU), and local generation—as alternatives for future compressed air usage. Environmental Value systems(EnVS) tools are employed to analyze the economic and environmental performance of the three alternative supply patterns by using cost of ownership and environmental impact matrices. The results favor local generation over the other two alternatives in terms of economic and environmental considerations.
The roller imprinting process is being developed for the efficient and accurate fabrication of microfluidic devices. As the precision of the imprinted features is dependent on the features of the imprint rolls used in the process, it is critical that the rolls are manufactured very accurately, conforming closely to their design. It is also important that imprint rolls are manufactured rapidly and cost-effectively to control the cost and lead-time of roller imprinting. This paper looks at the application of micromachining technology in the manufacturing of imprint rolls. Sources of error during the manufacturing process are identified, and their effect on the precision of the final imprinted feature is discussed. Toolpath planning strategies are presented for generating very smooth surfaces. The paper presents a framework of precision manufacturing requirements for the roller imprinting process.
Evaluation of the Effect of Pad Thickness and Stiffness on Pressure Non-Uniformity at Die-Scale in ILD CMP
In this study, 2^4 full factorial design of experiment was applied to an FEM model, which gives pattern dependant contact pressure distribution, to build a qualitative model of pad effects on within die non-uniformity (WIDNU) in CMP. Analysis of variance showed that every single effect and two-way interaction effects of hard layer stiffness and soft layer stiffness are significant compared to the round-off error from mesh change. Various regression models were built and residual analyses were done for each of them. Best model with best normality of residuals includes only the effect of hard layer stiffness, soft layer stiffness and hard layer thickness. Based on this model, basic qualitative design rule for a stacked CMP pad to minimize WIDNU were suggested.
Local material removal rate is inversely proportional to the local pattern density in ILDCMP. With the assumption that the local velocity and Preston coefficient are constant across a die, local MRR non-uniformity is attributed to the local pressure non-uniformity. Pressure distributions on two different test patterns consisting of five different pattern density sections were calculated with a finite element model. These pressure distributions were compared with semi-empirical pattern dependant oxide CMP model with three different weighting functions. Results showed that pressure distribution can be well approximated with the pattern density dependant oxide CMP model.