Jane C. Ammons

Robust reverse production system design for carpet recycling

It is estimated that complete carpet recycling would avoid an estimated US annual landfill cost of

Automated process planning for printed circuit card assembly

65 million, while simultaneously recovering lost material valued at

Carpet Recycling: Determining the Reverse Production System Design

750 million. Designing an adequate reverse production system is critical to the economic viability of recovering this lost value. We develop a robust-mixed-integer linear programming model to support decision-making for reverse production infrastructure design. Our robust model seeks solutions close to the mathematically optimal solutions for a set of alternative scenarios identified by a decision-maker. To demonstrate the approach, a representative industrial case study is given for a large-scale carpet recycling problem. A robust solution is found that appraises the impact of two major sources of uncertainty, volumes of carpet collected and price of a key recycled material.

A large scale machine loading problem in flexible assembly

Printed circuit card assemblies form the core of a vast array of contemporary manufactured products. The technologies for assembling printed circuit cards require a hierarchy of complex decisions for grouping card types and processes, staging components at assembly machines, arranging feeders, and sequencing placement operations. This paper is motivated by the largely unmet needs of industrial process planners for computer aids. Our objective is to develop a framework for the printed circuit card assembly process planning problem and to assess the current state of the research on appropriate models and solution methods. We first provide an overview of the essential elements of printed circuit card terminology, assembly technologies, and assembly system operations. Then we propose a decision hierarchy, survey the published literature, and identify needs for future research.

Strategic design of reverse production systems

Abstract Roughly 4 billion pounds of carpet are disposed of in the United States each year. This carpet is composed of a significant fraction of nylon, polypropylene, and polyester fiber. A key limiting factor to recycling is effective design and development of the reverse production system to collect and reprocess this large volume of valuable material. A reverse production system is composed of material and chemical recycling functional elements interconnected by transportation steps. In this article, we develop a mixed-integer programming model to support decision-making in reverse production system design. To illustrate its use and applicability, we apply the model to a representative U.S. carpet recycling industrial case study. The overall economic feasibility of recycling is strongly dependent on the volumes that can be expected from investments in collection infrastructure. The geographic location of processing centers influences the network economics, and the subdivision of recycling tasks to avoi...

Component allocation to balance workload in printed circuit card assembly systems

Flexible manufacturing is characterized by versatile work stations with minimum change over times and a versatile material handling system. The loading problem in flexible manufacturing is to assign tools, material, operations and jobs to work stations in order to minimize the total number of job-to-work station assignments. In this paper, we describe a special case of the general loading problem applied to flexible assembly and develop a discrete optimization model. We then discuss approaches for obtaining good heuristic solutions and present results for a large scale study.

The effectiveness of supervisory control strategies in scheduling flexible manufacturing systems

Increasing world population and standards of living are leading to increased resource use and disposal. To sustain ourselves at these levels of material comfort will require that our utilization of resources becomes radically more efficient. One strategy for achieving greater material efficiency is the recycling of products back into useful raw materials. Efficient recycling requires attention to the strategic design of reverse production systems. In this paper, we present the concepts and issues surrounding reverse production system design and an initial formulation to address some of the questions around its implementation. The formulation is as a mixed integer linear program and we utilize a robust optimization framework. This framework poses the objective as the minimization of the maximum deviation of the performance of the network from the optimal performance under a number of different scenarios. We illustrate the framework with the example of carpet recycling, which is currently being undertaken on a national scale in the US. The case study shows that the flexibility of the process technology to recycle as large a fraction of the collected materials as possible is a strong driver for overall economic effectiveness of the reverse production systems.

A Product and Process Selection Model with Multidisciplinary Environmental Considerations

Component allocation in printed circuit card assembly systems is a special case of the classical mixed-model assembly line balancing problem and involves assigning component types to machines to achieve specific production objectives. In this paper the component allocation problem is considered for the scenario where there are two or more placement machines (possibly nonidentical) and the objective is to balance, for every card type, a combination of the card assembly time and the machine setup time. A mathematical formulation of the problem is developed for a class of placement machines. Two alternative solution approaches are presented: a list-processing-based heuristic for a simple version of the problem, and a linear-programming-based branch-and-bound procedure for the general component allocation problem. Industrial case study results are presented for each approach that indicate expected throughput improvements of up to 8--10% over the companys current procedure, with much less direct effort required by the process engineer.

Planning the e-Scrap Reverse Production System Under Uncertainty in the State of Georgia: A Case Study

The results of an experimental study of the supervisory control of a simulated flexible manufacturing system (FMS) are discussed. A real-time simulator of an FMS, (Georgia Tech-FMS (GT-FMS)) was implemented and configured with data from a real manufacturing system. An experiment was run in which humans interacted with the automatic control system of GT-FMS with the goal of improving overall system performance by meeting due data while simultaneously minimizing inventory. Experimental results show that with human supervision both due data and inventory performance of GT-FMS can be improved. The results strongly support the idea of actively integrating humans into operational controls of automated manufacturing environments. >

Decision models for aiding FMS scheduling and control

Introduction of product designs and process innovation requires a company to evaluate complex cost and environmental tradeoffs. In the past, these have not included environmental costs. This paper describes the first known analytical approach to capture comprehensively measurable corporate environmental impact considerations for the product life cycle. A mixed integer programming model is developed to select product and process alternatives while considering tradeoffs of yield, reliability, and business-focused environmental impacts. Explicit constraints for environmental impacts such as material consumption, energy consumption, and process waste generation are modeled for specified assembly and disassembly periods. The constraint sets demonstrate a new way to define the relationship between disassembly configurations and assembly activities through take-back rates. Use of the model as an industry decision tool is demonstrated with an electronics assembly case study.