Showing papers in "International Journal of Production Research in 1975"
TL;DR: In this paper, a production lot size model for an inventory system with deteriorating items was developed for both the varying and constant rate of deterioration, and a numerical example was solved to show the impact of deterioration.
Abstract: SUMMARY A production lot size model has been developed for an inventory system with deteriorating items. Both the varying and constant rate of deterioration have been included in the analysis. For the case of a varying rate, it seems impossible to obtain a simple expression for the production lot size, so a numerical method has been suggested. For the constant rate of deterioration case, an approximate expression has been derived for the production lot size. Finally, a numerical example is solved to show the impact of deterioration.
349 citations
TL;DR: A method is presented for forming machine cells while implementing group technology in the form of a graph whose vertices correspond to the machines and whose edges represent the relationships created between the machines by the components using them.
Abstract: SUMMARY A method is presented for forming machine cells while implementing group technology. Information derived from the route cards of the components is analysed and the situation is represented in the form of a graph whose vertices correspond to the machines and whose edges represent the relationships created between the machines by the components using them. For finding the cells a graph partitioning approach is suggested and developed. Results obtained from testing the method using actual data are also presented.
314 citations
TL;DR: In this paper, a model sequencing algorithm for model-mix assembly lines is proposed, the objective function of which is to minimize the overall assembly line-length for no operator interference.
Abstract: SUMMARY This paper describes a model sequencing algorithm for model-mix assembly lines. A new formulation of the sequencing problem is proposed, the objective function of which is to minimize the overall assembly line-length for no operator interference. Lower bounds for the overall line-length are developed. Two types of work station interfaces are considered; ‘closed’, where boundaries cannot be violated, and ‘open’ where defined boundaries do not exist—adjacent operators being allowed to enter each others apparent work areas without causing any interference. A complete factorial experiment was made on five factors to determine their influence on the overall assembly line length. These are, the number of models, the model cycle time deviation, the production demand deviation for each model, the operator time deviation, and the number of stations in the assembly line. The main conclusions of this experiment are discussed and recommendations made for the selection of parameters used in the design of model...
110 citations
TL;DR: The relationship between temperature gradient, cutting speed and feed rate have been demonstrated through the heat affected region close to the cutting edge in high speed steel tools used to turn iron, titanium and nickel as mentioned in this paper.
Abstract: SUMMARY Temperature gradients in high speed steel tools used to turn iron, titanium and nickel have been measured using a method based on the structural changes in high speed steel heated to temperatures over 560°C. The relationship between temperature gradient, cutting speed and feed rate have been demonstrated through the heat affected region close to the cutting edge. The most emphatic feature of the results is that each of the three metals imposed its own and greatly different pattern of temperature distribution within the tool. It was shown that this controls some of the basic wear processes which limit the rates of metal removal. When cutting iron there was a relatively cool zone close to the cutting edge in the most highly stressed region, while the hottest part was well back from the edge; the temperature gradients were very Bteep. When cutting titanium the higher temperatures were much closer to the cutting edge, and the total heated region was smaller, while the temperature gradients were again ...
99 citations
TL;DR: A branch and bound algorithm is presented for its solution to the balancing assembly lines problem, formulated as a mixed integer programme, and preliminary computational results are provided.
Abstract: SUMMARY A critical assumption in balancing assembly lines is that the line is ‘ serial ’ with no ‘ paralleling’ of tasks allowed. This constrains the cycle time to be at least equal to the maximum task time, which in turn limits the production rate. One alternative to increasing the production rate (hence lowering the cycle time) is by allowing parallel tasks in the assembly line at the cost of additional facilities. In this case, the problem becomes one of selecting the tasks to be paralleled such that the total cost is minimized. This problem is formulated as a mixed integer programme, and a branch and bound algorithm is presented for its solution. The structural properties of this programming problem are discussed, which con be used to improve the computational efficiency of our branch and bound algorithm. An illustrative problem and preliminary computational results are provided.
84 citations
TL;DR: In this article, a comparison and selection of systems for the mass production, in particular the assembly, of complex discrete items is discussed. But the focus is on the non-quantifiable aspects of systems.
Abstract: SUMMARY This paper is concerned with the comparison and selection of systems for the mass production, in particular the assembly, of complex discrete items. A possible procedure is proposed for system selection based upon (a) an examination of the feasibility of using certain basic system types in particular situations, (b) a comparison of feasible alternatives based upon certain quantifiable factors, and finally (c) a study of the non-quantifiable aspects of systems. Basic system types are listed, a detailed procedure is proposed for the quantitative analysis and some relevant non-quantifiable factors are identified.
71 citations
TL;DR: In this paper, the authors present a reasonable procedure for determining the values of the various control variables of an S, c, e control system, namely the Order-up-to-levels, the can-order points and the mustorder points, assuming that demand is compound Poisson and the replenishment lead time is of negligible duration.
Abstract: SUMMARY Often coordination of items for replenishment purposes can lead to significant savings in the costs of replenishment. This article presents a reasonable procedure for determining the values of the various control variables of an (S, c, e) control system, namely the Order-up-to-levels, the can-order points and the must-order points. It is assumed that demand is compound Poisson and the replenishment lead time is of negligible duration. Comparison with the best independent control strategy indicates that substantial savings (averaging 15-9% over some 64 examples) are possible through coordination of replenishments.
68 citations
TL;DR: In this paper, the authors presented analytical solutions for the mean cycle time of a two-stage series production system with variable operation times at the stages, and showed that at high values of coefficient of variation, the type of service time distribution has a considerable effect on the overall throughput of the system.
Abstract: SUMMARY Analytical solutions for the mean cycle time of a two-stage series production system with variable operation times at the stages are presented. Although the methodology is applicable to any type of service time distribution at the stages, typical cases of Erlang and normal distributions are worked out in detail. It is shown that the problem of a multi-stage unpaced belt production system can, in principle, be reduced to one of integration, for arbitrary service time distributions at the stages. Detailed expressions are obtained for the mean cycle time and in process inventory of a two-stage series production system with provision for an arbitrary level of interstage inventory. The service time at one of the stages is assumed to be constant and the other distributed exponentially. The analysis leads to the conclusion that at high values of coefficient of variation, the type of service time distribution has a considerable effect on the overall throughput of the system and unbalancing has a favourabl...
65 citations
TL;DR: In this paper, a very brief overview of the main sociotechnical concepts and authors is given, followed by a rather critical examination of this approach, viz. from a methodological and a system theoretical standpoint.
Abstract: SUMMARY In this article first a very brief overview is given of the main sociotechnical concepts and authors. This is followed by a rather critical examination of this approach, viz. from a methodological and a system theoretical standpoint. After that some suggestions are given for an improvement, in sociotechnical thinking, that might be fruitful with respect to the development of a theory.
38 citations
TL;DR: The method provides a near optimum schedule for multi-product single machine systems, and is eminently suitable for those systems where machine utilization is high.
Abstract: SUMMARY In this paper, a method based on a new approach has been given for tackling the scheduling problem usually encountered when a number of products are manufactured on a single machine on a repetitive basis. The method provides a near optimum schedule for multi-product single machine systems, and is eminently suitable for those systems where machine utilization is high. An example has been solved for illustrating the method.
31 citations
TL;DR: In this article, the authors present some case studies of quality control practices based on the authors' visits to some manufacturing industries and the statistical methods applied in each quality control programme are emphasized.
Abstract: SUMMARY This paper presents some case studies of quality control practices based on the authors’ visits to some manufacturing industries. The statistical methods applied in each quality control programme are emphasized.
TL;DR: Several approximate continuous review, trigger point-reorder quantity models, differing in degree of complexity, are compared and evaluated under varying conditions as discussed by the authors, and their performances are compared to those of an exact model under the assumption of Poisson demand.
Abstract: Several approximate continuous review, trigger point-reorder quantity models, differing in degree of complexity, are compared and evaluated under varying conditions. Their performances are compared to those of an exact model, under the assumption of Poisson demand. The approximate models studied are (1) an economic order quantity (EOQ) analysis for determining the order quantity and a periodic review analysis of the “ newsboy ” type to set the reorder (trigger) point (2) a model which considers reorder point and order quantity interactions as developed by Hadley and Whitin ; and (3) a theoretically more accurate variation of the Hadley and Whitin model as given by Wagner.
TL;DR: A problem oriented linear string representation for trees and the concept of grammar are introduced as basic tools for symbolic computation of trees and planar graphs and the need of optimal algorithmic techniques is pointed out.
Abstract: SUMMARY Difficulties in recognition of planarity of graphs in the context of layout problems are reviewed. A problem oriented linear string representation for trees and the concept of grammar are then introduced as basic tools for symbolic computation of trees and planar graphs. A heuristic method to solve the layout problem is next discussed and the need of optimal algorithmic techniques is pointed out. Finally the application of list processing techniques for manipulation by computer is suggested.
TL;DR: In this article, the authors consider the design of variables acceptance sampling plans for a general lot distribution with known and constant variance and either an upper or lower specification limit, and examine the effects of bias, imprecision, and their combined effects on the operating characteristic curve.
Abstract: Variables acceptance sampling plans are designed under the assumption that measurement on the characteristic of interest may be performed without error. To the contrary, variables measurement tasks are often confounded by human inspection error and/or instrument test error. The net result may be characterized in terms of bias and imprecision, where (1) bias is the difference between the true dimension of a unit of product and the average of a long series of repeated measurements on that unit, and (2) imprecision is the dispersion of repeated measurements on the same unit of product. This paper considers the design of variables acceptance sampling plans for a general lot distribution with known and constant variance and either an upper or lower specification limit. Bias, imprecision, and their combined effects on the operating characteristic curve are examined in detail and found to be quite significant. A method is then presented whereby the variables sampling plan may be designed to explicitly compensate...
TL;DR: In this paper, the problem of the layout of multi-product lines is considered as an integral part of production system planning and five types of systems are identified: single machine, single machine case, single-machine case, multi-machine, single operator case, multiple-machine and multi-operator case.
Abstract: SUMMARY The problem of the layout of multi-product lines is considered as an integral part of production system planning. The paper discusses the stages in production system planning and identifies five types of system. The layout of multi-product lines involves determining the number of stations in the line, the machine type at each station, and the station at which each operation is to be performed. The problem is described in the context of work flow and work load. A special case, the single machine case, is identified and some methods for its solution discussed. A procedure for solution of the general case is proposed, consisting of these stages: construction of a line with uni-directional flow; elimination of uneconomic work stations; and simulation of alternative line configurations. The method is illustrated by a case study.
TL;DR: In this article, it is shown that the incidence of missed units is minimized if the operatives are placed in descending order of work rate along the conveyor. But, the work pieces (units) are processed by the first available work station, after which they are transferred to a separate system.
Abstract: A conveyor system consists of equally-spaced hooks passing before a number of work stations. The work-pieces (units) are processed by the first available work station, after which they are transferred to a separate system. When the processing times are independently and exponentially distributed, distributions of the inter-arrival times of units at the work stations are found and it is shown that the incidence of missed units is minimized if the operatives are placed in descending order of work rate along the conveyor.
TL;DR: In this article, a three parameter time constant learning curve model is applied to four case studies and the optimum parameters determined in the least sum of error-squared sense is determined.
Abstract: SUMMARY A three parameter time constant learning curve model is applied to four case studies and the optimum parameters determined in the least sum of error-squared sense. The error residuals are then analysed using correlation, regression, and cusum techniques. A global range for learning curve scatter is derived from grouped data. One case study establishes a sinusoidal trend additional to wide-band noise. In all cases studied there is correlation between successive error residuals so that there are many less sign changes than predicted from an assumption of normally distributed, uncorrelated scatter. A simulation model is documented which generates artificial learning curves with the requisite degree of correlation as evident in terms of the number of sign changes. The results of the paper may be used to establish the a priori scatter estimates necessary in various parameter estimation techniques developed for on-line prediction of human operator future performance.
TL;DR: In this paper, a model is proposed to predict lifting performance from a large number of task-related variables, such as age, gender, and cognitive ability of the subjects, with a correlation coefficient of 0-936.
Abstract: SUMMARY Despite the numerous studies on human lifting ability no Berious attempt has been made to devise an empirical prediction model based on a large number of task factors rather than individual factors. This paper first demonstrates that the effect of one variable (age) is similar in a study of 45 subjects using a non-compact object to that found in previous studies using compact objects. A model is proposed to predict lifting performance from a large number of task-related variables. A test of the model using the effects of five variables estimated from the literature was conducted. Twenty-six lifting conditions were tested and the model predictions matched the actual weights lifted with a correlation coefficient of 0-936. The implications for future extension of the model are discussed.
TL;DR: The loss-cost function for control schemes using np charts is derived and the loss- cost surface is investigated, and numerical examples of minimum cost designs are studied to see how variation in the various risk and cost factors affects the economic optimum.
Abstract: The loss-cost function for control schemes using np charts is derived and the loss-cost surface is investigated. Numerical examples of minimum cost designs are studied to see how variation in the various risk and cost factors affects the economic optimum.
TL;DR: The one-hole test has a mean predictive validity of 0-75 (N = 228) between test scores and rate of learning in the training school; and a mean concurrent validity of 1-66 [N = 307] between test score and mean production performance of experienced operators as mentioned in this paper.
Abstract: SUMMARY The one-bole test was developed to provide a situation in which unlike that in the Purdue peghoard and similar teste, the reach, grasp, move and position elements were consistent and their rate of improvement measurable. Results support the hypothesis tlmt measurements of rate of learning or of performance after 600 cycles of practice have a higher concurrent and predictive validity of production output than measurements of initial performance on the test. The one-hole test has a mean predictive validity of 0-75 (N = 228) between test scores and rate of learning in the training school; and a mean concurrent validity of 0-66 [N = 307) between test scores and mean production performance of experienced operators. Norms (N = 1422), reliabilities (W=158) and correlation of the one-hole test scores with anthropometric measurements, personality, intelligence, age and other manual dexterity tests are discussed.
TL;DR: In this article, a discrete-flow, closed-loop conveyor system with multiple loading and unloading stations is considered, and the system is reduced to an equivalent one-station system for which the balance of flow is described by a difference equation.
Abstract: SUMMARY A discrete-flow, closed-loop conveyor system with multiple loading and unloading stations is considered. An inherent capability of such a system is that certain cyclic variations in the input and output flow rates can be accommodated through the storage feature of the closed loop. The system is reduced to an equivalent one-station system for which the balance of flow is described by a difference equation. The solution of this equation yields feasibility conditions as well as guidelines for conveyor design optimization and for conveyor operation. A numerical example solution for a three-station conveyor is included.
TL;DR: The flow-shop sequencing problem with no wait in process and with jobs requiring dissimilar technological order for machine processing is formulated and a systematic method is suggested for obtaining the optimum solution.
Abstract: SUMMARY The flow-shop sequencing problem with no wait in process and with jobs requiring dissimilar technological order for machine processing is formulated in this paper A systematic method is suggested for obtaining the optimum solution to the sequencing problem An example of four jobs with four technological orderings for machine processing and four machines is solved to illustrate the suggested method
TL;DR: In this paper, the authors analyzed a multi-stage cyclic queueing system in which there are alternate service and transit Btagea, and derived an explicit expression for the average production rate.
Abstract: SUMMARY This paper analyses a multi-stage cyclic queueing system in which there are alternate service and transit Btagea. The service times are negative exponentially distributed, but it is shown that the transit time distributions may be any of a whole range of types, from constant to negative exponential. It is also shown that the production rate of the system does not depend on the individual mean transit times, hut only on the sum of these mean transit times. An explicit expression for the average production rate is derived and used in two examples, (i) a two-stage earthmoving project, and (ii) a four-stage asphalt paving project, to obtain regions of optimal haul fleet size, in the parameter space, so as to minimize the cost of the system.
TL;DR: An algorithm for determining the optimal schedule of jobs on identical parallel processors is developed and a proof of the algorithm is given which indicates the effectiveness of the algorithms as compared to complete enumeration.
Abstract: SUMMARY This paper deals with optimal scheduling of jobs on identical parallel processors. The paper develops an algorithm for determining the optimal schedule and gives a proof of the algorithm. The criterion used is that of minimizing the total cost for processing all jobs when the jobs are assigned non-decreasing waiting costs which are non-linear. Extension of the algorithm for jobs with due dates is also given. Computational results are given which indicate the effectiveness of the algorithm as compared to complete enumeration.
TL;DR: The operating characteristics of unpaced flow line systems and collective systems are investigated by means of computer simulation and comparisons between the two systems are made.
Abstract: The criticism of flow line methods has resulted in the consideration of alternative methods of production—one such method is the ‘ collective ’ method of working In this research note the operating characteristics of unpaced flow line systems and collective systems are investigated by means of computer simulation and comparisons between the two systems are made
TL;DR: The purpose of this paper is to present an efficient algorithm for complex scheduling problems generalizing those ideas that use dominance and better bound ideas to solve job-shop problems.
Abstract: Several algorithms have been presented for handling complex scheduling problems. These methods are computationally impractical when confronted with large problems. New algorithms have been developed for solving job-shop problems. They are more efficient than the previous ones because they use dominance and better bound ideas. The purpose of this paper is to present an efficient algorithm for complex scheduling problems generalizing those ideas.
TL;DR: In this paper, a more general measure of awkwardness was introduced to cover extended periods of lifting rather than a single maximum exertion, and it was shown that the criterion of duration of lifting at constant weight leads to the same results as the criteria of maximum weight lifted, while the height of the object at both the beginning and the end of the lift are different.
Abstract: SUMMARY Most current data on manual handling performance are in the form of single-factor studies using the criterion of maximum weight liftable and measuring its variation with experimental conditions. This does not always help the manager attempting to set safe handling limits as his/her application will involve many of the factors. A recent paper by Drury and Pfeil showed how the task-factors of height of lift and awkwardness of object could be combined with the age and sex of the materials handler to predict performance. This paper is an extension of these methods to incorporate more data on the effects of lifting height, introduce a more general measure of awkwardness and modify the model to cover extended periods of lifting rather than a single maximum exertion. It is shown that the criterion of duration of lifting at constant weight leads to the same results as the criterion of maximum weight lifted. Other findings are that the height of the object at both the beginning and the end of the lift are ...
TL;DR: In this paper, it was found that the critical tool contact length was almost exactly proportional to feed and that the threshold of unconditional stability for any feed can be defined in terms of controlled tool contact lengths.
Abstract: A simple technique for stabilization of the metal cutting process has been investigated. It was found when machining orthogonally on a tube with controlled contact tools that for a given feed per revolution there is a critical tool contact length below which instability will not occur irrespective of the width of cut. Further, it was found that the critical contact length was almost exactly proportional to feed. The threshold of unconditional stability for any feed can thus be defined in terms of controlled tool contact length.
Abstract: A finite horizon inventory problem is encountered whenever a product is procured/ manufactured/sold for a limited time, after which it is replaced by another product performing basically the same function but differing in design/appearance/performance. The conventional methods cannot be applied for analysing the finite horizon inventory problem due to the discrete nature of the cost function. In this paper mathematical models have been developed for a case when a product is packaged in a number of container sizes and offered for a limited time. An example has been solved illustrating the method.
TL;DR: In this article, a set of decision rules for scheduling in the job-shop environment were studied and their performance measured by four different, but reasonable, criteria, and the results of the study indicate that under most conditions and measured by several, but not all, of the criteria used, the rule serve the machine, awaiting service with shortest required service time, performs best.
Abstract: A considerable amount of research has been conducted into the use of decision rules for scheduling in the job-shop environment. The research discussed in this paper is of a similar nature but concerned with the use of rules for controlling the service operation to semi-automatic machines where, the. run times and service times are, in the main, deterministic. The set of rules studied is different to those of the job-shop scheduling problem since the. products are manufactured, under batch conditions. Producing for stock means that delivering dates are not important but the idle time of machines is very important. The behaviour of a set of ten rules is studied and their performance measured by four different, but reasonable, criteria. The results of the study indicate that under most conditions and measured by several, but not all, of the criteria used, the rule serve the machine, awaiting service with shortest required service time, performs best. That is the conclusion is similar to the job-shop studies ...