Metrics for Sustainable Manufacturing

A sustainable manufacturing strategy requires metrics for decision making at all levels of the enterprise. In this paper, a methodology is developed for designing sustainable manufacturing metrics given the specific concerns to be addressed. A top-down approach is suggested that follows the framework of goal and scope definition: (1) goal- what are the concerns addressed and what is the appropriate metric type to achieve the goal (2) scope what is the appropriate geographic and manufacturing extent. In this methodology, a distinction is made between environmental cost metrics and sustainability metrics. Utilizing this methodology, metrics focused on energy use, global climate change, non-renewable resource consumption, and water consumption are developed

Micro-burr formation and minimization through process control

This paper presents an investigation on micro-burr formation in machining. Micro-cutting is compared with conventional cutting in terms of cutting process characteristic and cutting conditions. In this paper, tungsten–carbide micro-mills were used to cut holes (in a drilling-like process) to investigate top burr formation. The size and type of burr created in stainless steel 304 are studied as a function of machining variables, which are feed, cutting speed and cutting edge radius, to help illuminate the micro-burr formation mechanisms. A series of experiments was conducted to study tool life as a function of cutting conditions. Tool life, here, is defined as the number of holes created before a significant increase in burr height. 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 model, which includes the effect of feed, cutting speed, and the interaction between the two, predicted the burr height and tool life values with an accuracy of about±15%

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

Modeling of Pressure Non-Uniformity at a Die Scale For ILD CMP

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

Model of a Burr Expert System

For the face milling process, many algorithms have been developed to optimize the tool path with respect to the burr formation process, and to predict the occurrence of burrs. However, collecting data to create the factual knowledge base for face milling burr expert systems has long been seen as too costly and time consuming due to the many parameters that influence the burr formation process in the face milling operation. A suitably designed part that captures in essence the distinguishing mechanisms of burr formation can be very beneficial in reducing the number of experiments performed. This paper describes the geometry of a workpiece and the machining strategy employed to generate the distinct face milling burr formation mechanisms. Measurement is limited to burr size parameters that directly influence the functionality of the workpiece edge and the ease of burr removal in further processing. The burr data collected after machining the specially designed workpiece is stored in the database. The database is designed using an Entity-Relationship model. This high level conceptual model helps structure the data in a fashion that renders this database highly suitable for planning applications. The database is designed to handle the most important queries raised by a process planner. For example, identifying insert materials that generate the smallest burrs for a given workpiece material, and so forth. The database also directly interfaces with the optimization programs like burr prediction and tool path planning that were developed for burr minimization in face milling. In addition, this database can be used as a standalone system, i.e. a "burr expert", to recommend cutting parameters or tools for a specific material