Showing papers on "Job shop published in 1975"

Search and Simulation Selection of a Job-Shop Sequencing Rule

Abstract: A standardized approach to selecting a simple sequencing rule for decentralized application throughout a job shop is developed and illustrated. The sequencing rule is a linear combination of decision factors, each of which is initially assigned a relative weighting. The rule is then used to determine the priority of each job in the queues, and resulting shop costs are determined by computer simulation. The coefficients of the priority function are thereafter modified by a patterned search procedure to find priority coefficients that minimize expected cost per order for a specified cost structure. The cost structure is a combination of multiple response measures for the shop. Rather than leading to a “single best rule” for all job shops, the approach is a “method for finding” a sequencing rule that performs well in any specific job shop situation.

Effects of Shop Size and Labor Flexibility in Labor and Machine Limited Production Systems

Abstract: This paper describes a simulation study that examines the influence of system size and labor flexibility on the performance effects of dispatching and labor control decision rules in labor and machine limited production systems. Four production systems are used—a small job shop, a medium job shop, a large job shop in which workers may be transferred between major organizational divisions, and a large job shop in which workers cannot be transferred between divisions. For each system the decision rules for dispatching and labor control are varied. Comparisons are made of the relative effects of the decision rules, for the different systems, on mean flow-time, flow-time variance and number of worker transfers. Results indicate that the effects of dispatching and labor control decision rules on flow-time measures are consistent for different size and labor flexibility combinations. With one exception, the effects on labor transfer measures are also consistent. Consistency here means that the directions of cha...

Coordinating Aggregate and Detailed Scheduling in the One-Machine Job Shop: II—Computation and Structure

Abstract: A previous research report of the authors presented a formal model of the one-machine job-shop scheduling problem with variable labor capacity. This report presents some computational experience with the algorithm proposed previously and a discussion of the structural aspects of the problem. Extensions and refinements of the algorithm are introduced to deal with nonsimultaneous job arrivals and the production smoothing problem. These results provide insight into the structure of the aggregate-detailed cost trade-off problem and suggest a good heuristic decision rule for problems of realistic size and complexity.

Interactive Planning: A Study of Computer Aiding in the Execution of a Simulated Scheduling Task.

Abstract: This paper examines some of the problems and possibilities of interactive decision-making within the experimental context of an industrial problem-production scheduling. An experiment is described in which subjects were required to produce items from, and generally control, a simulated job shop. A predictive facility was introduced into the simulation in order to study its effect on search strategies and, in particular, determine whether the decision horizon could be extended. One of the main themes underlying the experiment was an investigation of the extent to which subject problem-solving strategies could be formalized and incorporated into solution-seeking procedures. The experimental results show that the type of search was relatively unaffected by the predictive facility. An explanation of this result and a discussion of the subjects strategies is offered in the light of information obtained from the analysis of verbal protocol material.

Job-shop sequencing problem with no wait in process

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

Job Shop Scheduling with Due Dates and Operation Overlap Feasibility

Abstract: The job shop problem with due dates is formulated to allow overlaps among successive operations on a job. Multiple transports of sub lots and existence of setup times are two applications where this formulation can result in technologically feasible schedules. A procedure is described for generating overlap schedules and it is applied to eight test problems from the literature. The resulting schedules are compared to alternative schedules involving tardiness or overtime. The results indicate that the procedure is effective in generating multiple transport schedules for the manager's consideration. The comparative data provide useful tradeoff information for evaluation of alternatives and indicate that multiple transport scheduling may sometimes be a very economical way to try to meet due dates without using overtime operations.

Studies in a Simulated Job Shop

Abstract: The effectiveness of various scheduling or loading rules in a job shop has been widely studied through simulation, where a given shop can be subjected to alternative patterns of arrivals and processing. This study is particularly concerned with the case when arrivals are in batches, either of regular size or where the batch size is Poisson distributed, and when the batches arrive at regular time intervals, and certain empirical relationships between three loading rules are investigated. Two types of operational flexibility are examined, the first where more than one machine may perform a given operation and the second where changes in the sequence of operations are allowed, and the effect of such flexibilities on the expected job waiting time is determined. Finally, the effect of different procedures for determining due-dates for arriving jobs is investigated.

The impact of advancing due dates in a pure job shop

Abstract: SUMMARY The effect on shop performance of granting customer requests for setting earlier clue dates on jobs already in process in the shop was investigated, via computer simulation, for a five-machine pure job shop. One-replicate, two-way classification (with interaction) and contrasts were used to examine the effect on various measures of shop performance of (1) four levels of mean interarrival time, A, and (2) five levels of the percentage of all jobs with CKEDD (customer requested earlier due date) status, T. Regression equations were developed for each performance measure in terms of the independent variables, A and T.

Job shop scheduling in an electroplating environment

Abstract: As operating costs continue to escalate, management must become more aware of the importance of increased productivity through increased efficiency. Scheduling by priority loading rules is one way of contributing towards the improved operation of the job shop. A computer simulation was used to study the performance variations of scheduling with eight different priority loading rules, of a job shop in an electroplating environment. The processing set-up of the shop was unique in that various plated finishes were obtained on various base-metals from a single system in which the processing tanks were physically arranged in a single line in series, and each base-metal-finish combination followed a specific pre-determined processing route. The plating job shop environment described, is shown in simplified flow chart form in Figure 1. The work to be processed was placed on racks and subsequently on to a movable bar before being transferred between the various processing tanks using automatically programmed travelling hoists. For our purposes, this system can process any one of the following base metal-finish combinations: Base metal finish (i) Zinc-brass (ii) Zinc-chrome (iii) Steel-brass (iv) Steel-chrome