問25
頻出度★★☆
工程間の仕掛品や在庫を削減するために, 必要なものを必要なときに必要な数量だけ後工程に供給することを目的として, 全ての工程が後工程からの指示や要求に従って生産する方式はどれか。
平成25年度 秋期 ITパスポート試験 問25
This question's explanation and your answers so far.
解説
問 25
- ア
正解 The correct answer is ア, the Just-In-Time (JIT) production method. Just-In-Time (JIT) is a production method that produces and supplies only the necessary items, in the necessary quantity, at the necessary time, thereby keeping work-in-process and inventory between processes to a minimum. It is the core idea of the Toyota Production System, and the means of realizing it is the Kanban method: the downstream process uses a kanban to tell the upstream process which parts and how many are needed, and the upstream process replenishes only the amount that was withdrawn. This flow, in which the downstream process withdraws from the upstream process and every process produces according to the instructions and requests of the downstream process, is called a pull system, and it matches exactly the statement in the question that every process produces according to the instructions or requests from the downstream process. Eliminating the waste of overproduction reduces work-in-process and inventory and prevents capital from being tied up; on the other hand, because there is no inventory cushion, a parts shortage, a late delivery, or a sudden swing in demand can easily stop the entire production line, which is its weak point. The thorough elimination of waste represented by JIT is also known as lean production.
Incorrectイ
The cell production method abandons the division of labor along a conveyor belt (line production) and instead has one worker or a small number of workers handle the assembly of a product from start to finish inside a small work area, such as a U-shaped cell. Its aim is flexible response to high-mix low-volume production and specification changes, and to make workers multi-skilled; its focus is on how processes are organized and how much of the work each worker covers. It is not a method that defines the flow of information between processes, which is what the question describes when it says that production follows the instructions or requests from the downstream process.
Incorrectウ
The make-to-stock production method produces in advance based on demand forecasts and sales plans, holds the products as inventory, and ships from that inventory when an order arrives. It is a push system in which the upstream process pushes output according to a plan, the opposite direction of the question, which starts from the request of the downstream process. It also assumes that inventory is held, so it runs counter to the stated goal of reducing work-in-process and inventory.
Incorrectエ
The lot production method produces the same product together in fixed batches (lots), then performs a changeover and moves on to the next product type. The aim is to raise efficiency by reducing the number of changeovers, but because items are made in batches, work-in-process and inventory tend to accumulate between processes, which does not match the question’s requirement of supplying only the necessary quantity to the downstream process. It is a term about how production is grouped in terms of quantity, and it does not describe a mechanism of instructions originating from the downstream process.
ここがポイント
- Just-In-Time (JIT) production method = producing and supplying only the necessary items, in the necessary quantity, at the necessary time, so as to eliminate the waste of work-in-process and inventory. It uses downstream withdrawal (a pull system), in which the downstream process tells the upstream process the quantity it needs, and the means of realizing it is the Kanban method, which uses slips called kanban.
- Organize the production-method terms by what each one focuses on. JIT and the Kanban method describe the flow of instructions between processes (a pull system); make-to-stock and make-to-order describe what triggers production (a forecast or an order); lot production, individual (job) production, and continuous production describe how production volume is grouped; cell production and line production describe how processes are organized and how much of the work each worker covers.
用語