Harold J. Steudel

A within-cell utilization based heuristic for designing cellular manufacturing systems

The initial stage in the facilities design of cellular manufacturing systems involves the identification of part families and machine groups and forming cells possessing specific manufacturing capabilities. A new heuristic for the part family/machine group formation (PF/MGF) problem is presented in this paper. The distinguishing feature of this heuristic is its consideration of several practical criteria such as within-cell machine utilization, work load fractions, maximum number of machines that are assigned to a cell, and the percentage of operations of parts completed within a single cell. Computational results, based on several examples from the literature, show that this heuristic performs well with respect to more than one criteria. The heuristic also clarifies the source of various arguments in the literature concerning the ‘goodness’ of the solutions obtained by other researchers. An application of the heuristic to a large sample of industrial data involving 45 workcentres composed of 64 machines,...

A decision-table-used processor for checking completeness and consistency in rule-based expert systems

Abstract This paper addresses the issues of completeness and consistency in rule-based expert systems. The approach presented uses decision tables, which have a close relationship to rule-based knowledge bases. A decision-table-supported processor is described which checks knowledge bases for completeness and consistency using this approach. It creates a large decision table from the rules of the knowledge base, splits the decision table into subtables with similar logic, checks each subtable for completeness and consistency, and reports any missing rules. This method is faster than enumeration only methods of checking completeness, and provides implicit context determination of production rules.

Complementary Use of Qualitative and Quantitative Cultural Assessment Methods

The organizational cultures of two small manufacturers were analyzed using qualitative and quantitative assessment methods. This article describes not only how qualitative and quantitative data contributed to the validity of the results through triangulation but also how the qualitative and quantitative research paradigms were used in a complementary fashion to produce a more complete understanding of the organizational cultures. Using methods from both research paradigms enabled a greater understanding of cultural artifacts and behaviors but more important of the underlying cultural values and assumptions. Based on this experience, it is recommended that qualitative and quantitative methods be used to produce more robust results than could be accomplished using a single approach for cultural assessment.

A study of labor assignment flexibility in cellular manufacturing systems

The objective of this research is to study labor flexibility in cellular manufacturing systems characterized by intra-cell operators mobility. The special focus of the investigation is to explore the impact that using different labor allocation strategies have on system performance. This internal aspect of labor flexibility is referred to as labor assignment flexibility. Labor strategies are classified according to the type of machine-operator assignments including dedicated (when only one operator is responsible for a machine or group or machines), shared (when more than one operator is responsible for a machine or a group of machines) or combined assignments (when the operator has both dedicated and shared machine assignments). This work proposes a classification scheme and a framework that is composed by a set of propositions that evolved from an empirical study and includes the concepts of workload balancing, workload sharing, and the presence of bottleneck operations. The suitability of the framework is tested using simulation modeling in an actual cell implementation. The experimental results based on labor strategies using two and three operators show that the balance in the workload assigned to the individual operators and the level of shared workload are significant factors in determining the performance of the system.

Computer-aided process planning: past, present and future

Abstract The role of process planning in small-batch, discrete parts metal working industries and the impact of the computer in automating this important but tedious job are discussed. The nature, advantages, and limitations of the manual, variant, and generative approaches to process planning are presented along with a review of the progress to date for each approach. A major thrust of the paper is to discuss approaches and strategies for structuring manufacturing methods and data in decision logic formats applicable for developing generative type automated planning systems. Although no particular approach is promoted, the paper provides an overview and information useful for approaching the task of designing a generative type system. Some detailed discussion on part coding schemes and structuring decision logic for generative type planning systems is also presented. The paper concludes with a brief discussion of the future of computer-aided process planning and the role that micro-computers will play in...

Cellular manufacturing for small businesses: key cultural factors that impact the conversion process

Abstract Companies converting to cellular manufacturing (CM) often struggle with implementation and achieve results that are less than anticipated. The existing body of CM research, with its strong emphasis on technical aspects, does not provide practitioners with the assistance needed for successful implementation. Since organizational culture is a strong barrier to change, this research aimed to reveal how culture impacts the CM conversion process. Two exploratory case studies were conducted at small manufacturing companies leading to the identification of eight key cultural factors that impact CM conversion.

A dynamic programming based heuristic for machine grouping in manufacturing cell formation

Abstract This paper presents a two stage heuristic for solving the machine grouping problem encountered in the identification and formation of flexible manufacturing cells. A new similarity measure, called Cell Bond Strength, is introduced which exploits similarity in processing for pairs of machines. The Cell Bond Strengths values are calculated based upon part routing and production requirements data. In the first stage of the heuristic, a Dynamic Programming procedure is used to determine an optimum “chain” of machines in which the sum of the bonds between machines is maximized. The second stage of this heuristic partitions the chain to form machine cells, subject to cell size restrictions. An example is given to illustrate the heuristic procedure. A summary of computational results when the heuristic is applied to several examples from the literature is also presented.

Integration of job shop control systems: A state-of-the-art review

Abstract This paper reviews important theoretical and practical developments in job shop control. The distinguishing feature of this paper is the identification and summary of important concepts and procedures useful for incorporation into computerized job shop control systems. The first section briefly examines the job shop control problem, and presents a broad outline of commonly used subproblems and methods. A review of the past work done in the areas of scheduling and sequencing, workload balancing, work flow structure analysis, and job shop capability evaluation is then presented. The final section lists important concepts and procedures for developing computer integrated job shop control systems.

Analysis of heuristics for job sequencing in manufacturing flow line work-cells

Abstract This paper addresses the problem of sequencing a set of n similar jobs through a Group Technology (GT)-structured flow line work-cell that is comprised of m dissimilar machines. The sequencing problem considers the factors of treating set-up times separately from processing times, finite buffers between machines, and piece-by-piece continuous flow processing. Sequencing heuristics are evaluated with the objective of minimizing the maximum flow time or makespan for a set of jobs—a practical criterion for processing a set of jobs in a Just-In-Time (JIT) manufacturing environment where parts are only processed to satisfy order-driven assembly requirements. Three new heuristics and four existing heuristics are presented and evaluated for both small and large problems. Numerical results show that while a branch-and-bound algorithm with a breadth-first search rule and sequence-dominance elimination yields the exact solution of small problems within a reasonable time, a random permutation heuristic is typically the best sequencing strategy for medium-to-large problems in terms of solution accuracy and computational time. The results of this research can be easily embodied in a PC-based sequencing tool for shop floor managers who need to sequence daily JIT production requirements, and determine the minimum make-span and corresponding labor requirements for each work-cell.

STAR*CELL: a flexible manufacturing cell simulator

This paper discusses STAR⋆CELL, a PC-based simulator for the design and evaluation of flexible manufacturing cell (FMC) flow line systems. As a design tool, STAR⋆CELL aids in determining the ideal number of machines, number and assignment of operators, and the size of inter-workstation buffers. The menu-driven simulator also assists in evaluating the impact on cell performance of Just-in-Time (JIT) factors, changes in product mix and demands, and different user-specified job input sequences. The paper provides numerical results for a gear workcell example to illustrate the effects of various design variables on cell performance. A brief discussion of the development, applications, advantages, and limitations of STAR⋆CELL is also presented.