Yoshinari Yanagawa

The optimal operation planning of a Kanban system with variable lead times

Abstract In the majority of the previous research on Kanban systems delivery lead time is treated as a fixed value. In many practical situations, however, the lead time is variable. In this paper, optimal operation planning of a fixed interval withdrawal Kanban with variable lead times is proposed. A cost is incurred for inventory level less than the safety inventory level, since the risk of shortage of inventory must be considered. Behaviour of the optimal number of Kanbans and the withdrawal interval of Kanbans are investigated in terms of various parameters such as standard deviation and mean lead time.

An optimal operation planning for the fixed quantity withdrawal Kanban system with variable leadtimes

Abstract This paper deals with an optimal operation planning for the fixed quantity withdrawal Kanban system with variable leadtimes and different consumption rates of parts for each production term. The behaviour of the optimal operation planning which minimizes the average total operation cost is shown by means of simulation analysis of various values of parameters: the order cost factor, the range of consumption rates of parts and the range of leadtimes for delivery.

Scheduling in an automated flow shop to minimize cost: Backward-meta scheduling method

Abstract Recently, computer integrated manufacturing (CIM) has become the most practical production system. Nevertheless, some problems appear in the stage of scheduling that are effected by the complexity of the system. Especially, CIM is classified to be an on-line system that has to decide the production schedule within a very short period. Nowadays, among the applied scheduling rules in CIMs, meta scheduling methods such as GA and SA have been widely used. In this paper, we have applied some meta scheduling methods to a model of CIM that is referred to as an automated flow shop, where backward scheduling should be used to realize a JITs theory. For the objective function, we have intended to minimize the total cost calculated through the production schedule of orders. Scheduling methods have been constructed and tested in the scheduling model by conducting the simulation test. Finally, results of the simulation test have been compared to find the performance of the proposed method.

Mixed-Model Assembly Line Scheduling in Consideration of Assembly Time

In a mixed-model assembly line problem, two objectives has been proposed to decide the product scheduling. One is to minimize the work congestion and the other is keeping the consumption rate of each part. In JIT production system, the latter one is more important, so the goal chasing method (GC) has been prposed to achieve this goal. The difference of assembly time among each product was not cnsidered in any solution algorithms. Recently, the time based goal chasing method (TBGC) has been proposed in which the different assembly time among each product is considered. The good point of TBGC is able to consider the idle time contained in an assembly line. However, TBGC is only applied to a single work station problem. In this paper, TBGC is applied to an assembly line and numerical experiments are presented.