Buffer stock allocation in serial production lines

2002

Buffer allocation is a challenging design problem in serial production lines that is often faced in the industry. Effective use of buffers (i.e. how much buffer storage to allow and where to place it) in production lines is important since buffers can have a great impact on the efficiency of the production line. Buffers reduce the blocking of the upstream station and the starvation of the downstream station. However, buffer storage is expensive both due to its direct cost and the increase of the work-in-process inventories it causes. Thus, there is a trade-off between performance and cost. This means that the optimal buffer capacity and the allocation of this capacity have to be determined by analysis. In this thesis, we focus on the optimal buffer allocation problem. We try to maximize the throughput of the serial production line by allocating the total fixed number of buffer slots among the buffer locations and in order to achieve this aim we introduced a new heuristic algorithm called "Line Balancing Algorithm (LIBA)"applicable to all types of production lines meaning that there is no restriction for the distributions of processing, failure and repair times of any machine, the disciplines such as blocking, failure etc. and the assumptions during the application of LIBA in the line.

2001

In the paper a new efficient algorithm for the allocation of storage capacity in serial production lines is derived. The proposed method aims to find out the distribution of storage capacity between machines that minimizes the total buffer space assigned to the line satisfying a target production requirement. The algorithm relies on an iterative scheme that, starting from the minimal capacity required in each buffer to meet the production requirement, proceeds increasing the capacity of buffers until the target production rate is reached. At each iteration the buffer corresponding to the largest component of the gradient of production rate with respect to each buffer capacity is selected and its capacity is increased by a small amount of space. The effect of such an increasing is then estimated by applying the decomposition technique to the resulting line. Preliminary numerical results shows that the buffers distribution provided by the algorithm is optimal or near optimal and that ...

International Journal of Production Research, 2006

Buffer allocation in serial production lines is one of the important design issues, and hence it has been studied extensively in the literature. In this paper, we analyse the problem to characterise the optimal buffer allocation; specifically, we study the cases with single and multiple bottleneck stations under various experimental conditions. In addition, we develop an efficient heuristic procedure to allocate buffers in serial production lines to maximise throughput. The results of the computational experiments indicate that the proposed algorithm is very efficient in terms of both solution quality and CPU time requirements. Moreover, the characterisation study yields interesting findings that may lead to important practical implications. A comprehensive bibliography is also provided in the paper.

2017

We consider a production line consisting of several machines in series with finite intermediate buffers. The machines have geometrically distributed processing times. We address the problem of determining the optimal buffer sizes to maximize the average profit of the line subject to a minimum average throughput constraint, under three operating policies. The average profit is defined as the weighted average throughput of the line minus the sum of the weighted average WIP plus total buffer capacity. The considered policies are: installation buffer (IB), echelon buffer (EB), and CONWIP. IB is the traditional policy under which a machine can store the parts that it produces only in its immediate downstream buffer. Under EB, it can store them in any of its downstream buffers. CONWIP is a special case of EB where the capacities of all buffers, except the last one, are zero. To find the optimal buffer allocation for each policy, we use a two-step gradient algorithm, where the average prof...

International Transactions in Operational Research, 1998

This work deals with the buer allocation problem in balanced production lines. The workstations of the lines consist of single machines which are assumed to be perfectly reliable, i.e., they don't break down. The processing times follow the exponential or Erlang-k (k = 2,3,4) distribution. The paper presents two basic design rules that were extracted for the optimal buer allocation in these types of lines using enumeration. We have developed a search technique that gives the optimal buer allocation very fast. This is a modi®ed Hooke±Jeeves search algorithm that exploits the two design rules to give an initial buer allocation close to the optimal one. The rules are exploited via the use of the proposed Allocation Routine. The latter was found to give the optimal solution in almost all cases examined in this study. # 1998 IFORS. Published by Elsevier Science Ltd. All rights reserved H. T. Papadopoulos and M. I. VidalisÐBuer Storage Allocation 326

Mathematical Problems in Engineering, 2004

In this study, the buffer allocation problem (BAP) in homogeneous, asymptotically reliable serial production lines is considered. A known aggregation method, given by Lim, Meerkov, and Top (1990), for the performance evaluation (i.e., estimation of throughput) of this type of production lines when the buffer allocation is known, is used as an evaluative method in conjunction with a newly developed dynamic programming (DP) algorithm for the BAP. The proposed algorithm is applied to production lines where the number of machines is varying from four up to a hundred machines. The proposed algorithm is fast because it reduces the volume of computations by rejecting allocations that do not lead to maximization of the line's throughput. Numerical results are also given for large production lines.

International Journal of Manufacturing Technology and Management, 2003

Bottleneck station is defined as a point in the manufacturing process that holds down the amount of product which a factory can produce. It causes the inability of a system to respond to sudden changes in demand as a result of capacity restrictions. The study focuses on unbalanced lines in which one station, so called the bottleneck, has either a mean processing time or a variance larger than all other stations. By providing storage buffers, it has shown that line blocking and starving may be solved. However, the optimal placement of a predetermined amount of buffer capacity in different types of bottleneck condition is not well understood. Thus, this paper studies the relationship of bottleneck and buffer factors. These are factors that show characteristics of bottleneck condition and buffer type (e.g., size and position). Various statistical analyses are then used to find any significance or insignificance of performance measures under each situation. Results from the experiment have revealed some interesting knowledge in allocating storage buffers for productivity improvement.

International Journal of Industrial and Systems Engineering, 2019

The buffer allocation problem (BAP) is one of the major optimisation problems faced by production system designers. BAP is widely studied in the literature since buffers have a great impact on efficiency of production lines. This paper deals with buffer allocation problem and compares

MATEC Web of Conferences, 2016

The objective of this paper is to demonstrate a determination of buffer to increase line efficiency in a transfer line where several workstations are linked together by a conveyer. One of the common problems of a transfer line is minor stoppages i.e. part short, machine adjustment, and so on are the typical problems which result in low uptime efficiency and are detrimental to productivity. Thus, buffer stock is designed to mitigate the problem; however, knowledge in determining optimal number of buffers is not prevalent. The buffer analysis using constant downtime distribution is employed in this paper.