James F. Cox

Multiple criteria approach to the facilities layout problem

Abstract Thin paper presents a multiple criteria model for combining quantitative and qualitative approaches to plant layout. The quantitative factor (work flow) is weighted by the qualitative factor (closeness rating) to form the model. The objective is to minimize the total weighted work flow volume between departments. An heuristic approach is used on an initial layout to improve it in a multiple puss step-by-step pairwise exchange. The results indicate that the model does an excellent job, especially in separating those departments which have an undesirable closeness rating.

Optimum production technology (OPT) and the theory of constraints (TOC): analysis and genealogy

(1995). Optimum production technology (OPT) and the theory of constraints (TOC): analysis and genealogy. International Journal of Production Research: Vol. 33, No. 6, pp. 1495-1504.

Problems in implementing and operating a manufacturing resource planning information system

Abstract:Manufacturing information systems are among the most complex to design, implement, and maintain. Few systems are completely successful. This paper provides the framework of one of the most popular manufacturing information systems, a manufacturing resource planning system, discusses the potential benefits of a successful system, and describes the problems associated with operating the system. Problems are classified as being management, technical, and behavioral. Recommendations are provided for each type of problem based on an extensive review of the literature. A discussion is provided of current trends in the manufacturing information system field.

Designing unbalanced lines - understanding protective capacity and protective inventory

The purposes of this paper are, first, to introduce several concepts and definitions related to Theory of Constraints design and management of unbalanced lines and, second, to illustrate the concepts of productive and protective capacity and inventory in a constrained line. Drum-buffer-rope is the Theory-of-Constraints based scheduling mechanism used to manage throughput at constraint work stations and flow at non-constraint work stations. A small simulation model is given to illustrate the importance of protective capacity and protective inventory at non-constraint stations. The line consists of several stations with the centre station being the constraint station. The capacity of (and inventory at) non-constraint stations is varied during the simulation. Line output increases as inventory at non-constraint stations increases. This result is contrary to traditional teaching about line design which says that line output is a function solely of the capacity of the slowest station.

A tutorial on project management from a theory of constraints perspective

Managing projects is a difficult undertaking–a large number of projects fail to be completed on time, on budget, or to specifications. In traditional project management literature, researchers criticise project manager skills and leadership, user involvement, top management commitment, organisation, etc. More recently, research has identified underlying problems with project concepts. We briefly describe the types of failures (late delivery, over budget, less than full specs) of projects. Second, we examine some causes of project lateness. Third, we illustrate the calculations for project completion using traditional and critical chain project methodologies. We then conduct three small simulations of the network using uniform, triangular, and exponential distributions to determine the impact of using the critical chain methodology on project completion dates. Last, we provide some references discussing critical chain project management.

An analysis of the product-process matrix and repetitive manufacturing

Researchers in management and marketing theory have long postulated a role between and management strategies used for the production process and for the products. Hayes and Wheelright (1979a) developed the product-process matrix to describe the relationship and in a following article (1979b) they identified strategic consequences implied by the matrix. During the 1980s confusion arose concerning the proper identification of the process categories used in the product-process matrix. Further, confusion arose concerning the role of repetitive manufacturing as a production category when just-in-time methods were explored. An empirical study was conducted to properly identify the role of repetitive manufacturing and to better define the categories used in the product-process matrix

Addressing ill‐structured problems using Goldratt's thinking processes

Purpose – Problem‐solving techniques for poorly structured problems have been the subject of recent academic research and popular press texts. The purpose of this paper is to explain the use of one of the Theory of Constraints thinking process (TP) tools — the Current Reality Tree (CRT). The purpose of the tool is to clearly identify the root problem or problems that cause the surface problems or undesirable effects occurring in an organization.Design/methodology/approach – One must fully understand the core problems in the environment before proposing a system solution to these core problems. Without this systems perspective, a proposed solution may create more problems than it solves. Through the use of an actual white‐collar service case, the paper explains how the CRT is created.Findings – The overall objective of this research is not to propose solutions to the case but to demonstrate how the CRT might provide structure by identifying and logically linking the surface problems encountered in each are...

Competitive factors and performance measurement: Applying the theory of constraints to meet customer needs

This article presents an analysis describing how the selection of proper competitive factors and modification to a firms performance measurement system provide the means to control, coordinate and communicate product flow, from order receipt to customer shipment, through the production process. The article also discusses how modifications to the traditional manufacturing planning and control model to reflect the principles of the Theory of Constraints (TOC), along with the selection of proper competitive factors provide a means of synchronizing the production process to an ever-more demanding market. A performance measurement system that directs managements attention to the needs of the customers rather than to the internal concerns traditionally measured is advanced. A case study is included that characterizes the operation of an engineer-to-order manufacturing organization. This firm changed its competitive focus and its performance measurement system in response to a erratic sales pattern brought about by an inability to respond to customers requirements in terms of lead time and delivery promises. Using the principles advocated by TOC the organization was able to reduce lead time and improve delivery performance to a point where the operation became a preferred manufacturing location in the corporation. The cost measurement system was changed from a traditional standard cost system to a system utilizing TOC principles. A cost measurement system that measures global costs rather than individual component cost can also be a decisive factor in coordinating sales and manufacturing efforts within an organization. The relationship between these various factors is explored in the case study.

Process flow industry-scheduling and control using theory of constraints

This paper discusses the applicability of the Theory of Constraints (TOC) in the process flow industry and compares TOC to the current practice. The Drum-Buffer-Rope methodology is altered to meet the needs of the process flow environment. Guidelines for the strategic location of and determination of the reduced WIP inventory levels are provided.

Constraint‐based accounting and its impact on organizational performance: a simulation of four common business strategies

Since its inception, cost accounting has provided data to managers for the development of internal organizational performance measures. In the mid 1980s, Dr Eli Goldratt introduced a new management philosophy called the theory of constraints (TOC). This philosophy contained a new set of performance measures which linked together the strategic objectives and operational capabilities of the organization. This linkage allows for the maximization of profits. Since its introduction, there has been a growing amount of evidence documenting TOC’s ability to more tightly link local decisions to organizational performance than those of traditional cost accounting. This research used a simple Gedunken experiment to evaluate the difference between strategy driven product‐mix decisions based on TOC accounting and traditional cost accounting. In all cases, the constraint‐based approach to costing outperformed the traditional approach based on cost accounting.