Sabry Shaaban

The effects of joint operations time means and variability unbalance on production line performance

In this paper unpaced, unbalanced lines with respect to both their mean operation times (MTs) and Coefficients of Variation (CVs) were simulated with different lengths, buffer capacities, degrees of imbalance, and patterns of imbalance. Idle Time (IT), throughput and Average Buffer Level (ABL) data were generated and analysed. The best unbalanced configurations in terms of IT/throughput and ABL were respectively found to be an MT inverted bowl combined with a bowl shaped CV pattern, and an MT decreasing order combined with a bowl CV arrangement. The best patterns provided generally superior performance to that of a balanced line counterpart.

The performance of unpaced serial production lines with unequal coefficients of variation of processing times

In this paper, the behaviour of non-automated production lines in terms of their service time coefficients of variation is studied. Results from the simulation of such lines under their steady-state mode of operation with varied buffer storage sizes, number of stations, imbalance configurations and a range of coefficients of variation are presented. Extensive statistical analysis of the output shows that the best pattern (a bowl-shaped arrangement) gives simultaneously lower idle times and lower average buffer levels than those of a balanced line. Predictive formulae and design factor impacts on the endogenous variables are also presented.

The performance of unpaced production lines with unequal operating time variabilities and buffer sizes

This paper investigates the behaviour of unpaced production lines that are imbalanced with respect to both their work time coefficients of variation and buffer sizes. The lines were simulated with varied values of line length, buffer capacity and patterns of imbalance. Using a range of statistical methods, idle time and average buffer level (ABL) output data were analysed and compared to a balanced line counterpart. Various conclusions concerning the relationships among the exogenous and endogenous variables were made. The best pattern in terms of idle time was identified to be a bowl-shaped coefficient of variation configuration, combined with a buffer arrangement whereby more buffer capacity is concentrated at the beginning of the line. In terms of ABL, the superior pattern turned out to be a bowl-shaped coefficient of variation order, together with a buffer arrangement under which the buffers are concentrated towards the end of the line.

Unpaced production lines with jointly unbalanced operation time means and buffer capacities – their behaviour and performance

The performance of unpaced production lines that are unbalanced in terms of both their operation time means and buffer storage sizes is studied in this paper. The lines were simulated under their steady-state operational mode of operation with various values of line length, buffer storage capacity, degree of imbalance, and patterns of imbalance. Output data (principally idle time and average buffer level) were analysed utilising a number of statistical tools. In terms of idle time, it was found that the best unbalanced pattern is an MT bowl configuration, coupled with a distribution of buffer capacity as evenly as possible. With respect to ABL, the best pattern turned out to be a monotone decreasing MT order, together with an ascending buffer size order.

Production line efficiency : a comprehensive guide for managers

This book covers the area of unpaced, unbalanced production lines. You will find an up-to-date discussion of how designing these lines can be made more efficient by taking advantage of inherent imbalance, for example operators who work at different speeds - a concept which has traditionally been seen as an obstacle to efficient production. A series of experiments are presented to illustrate the issues involved in improving performance through production line imbalance. This area is of interest to postgraduate and executive level students interested in the area of production, and to managers of manual or semi-automated production lines who are interested in innovative approaches to line design. In this book you will find some surprisingly easy ways to improve performance with low or zero costs. Emphasis is placed on reducing the amount of time production lines lie idle, and on reducing work in process. This is a timely contribution to the field when managers are casting around for new ways to cut waste and reduce their use of natural resources.

Performance of Reliable and Unreliable Unpaced Production Lines with Uneven Buffer Allocation

Abstract We compare the efficiency of reliable and unreliable unpaced production lines that are unbalanced in terms of their buffer storage capacities to a corresponding line with equal sized buffers. The lines were simulated with different values of line length, buffer storage size, mean buffer capacity, and configuration of buffer imbalance. The results show that, for both reliable and unreliable lines the best buffer allocation patterns in terms of generating lower idle times as compared to a balanced line are those where total available buffer capacity is allocated as evenly as possible between workstations, whereas concentrating more buffer capacity towards the end of the line gives best average buffer level results.

Reliable and Unreliable Unpaced Production Lines with Unbalanced Operation Time Means – A Comparison

Abstract Reliable and unreliable unpaced production lines are simulated with various line lengths, buffer capacities, degrees of mean processing time imbalance and patterns of imbalance. Performance measures are idle time and average buffer level. It was found that for both reliable and unreliable lines, the best configurations are a bowl arrangement and a monotone decreasing order, with the first resulting in lower idle times and the second leading to lower average buffer levels.