بررسی ترکیب و حجم انعطاف پذیری سیستم تولید ناب

This paper introduces a practice-oriented and field-tested approach to measure and evaluate volume and mix flexibility of a lean production system. After an introductory literature review revealing and classifying various types of flexibility as well as models to determine the flexibility of production systems, the most important flexibility types – volume and mix flexibility – are identified. Existing approaches for volume and mix flexibility evaluation are hard to implement in practice for different reasons: They are often bound to specific constraints or require extensive and complex input parameters. Additionally a lot of these models neglect the actual demand for flexibility. Lean production systems strive for a reduction of throughput times by eliminating non-value-adding work. In a perfectly lean and flexible production system responding to volatile demands, time gaps between customer demand dates and production dates would be removed completely for every single order. The model designed therefore uses the capacity-weighted difference of demand and corresponding production in a restricted time period for each product variant in relation to the total capacity demand.

Because of shorter product lifecycles and a rising product variety, the manufacturing industry today faces enormous challenges concerning the satisfaction of the customers demand. Due to the growing dynamic and variation in demand modern production systems have to competitive position [1]. Customers expect short lead times even when their demand changes. This means that a production system has to be able to adapt itself to a new market situation as fast as possible. Nevertheless a high flexibility also results in higher costs [2]. From an economic point of view this means that a lean production system should not be more flexible than absolutely necessary. Until today various sophisticated models to evaluate manufacturing flexibility have been developed. However a lot of them are hard to implement in practice as they are limited to specific constraints. In this scientific paper a practice-oriented approach to evaluate volume and mix flexibility is presented. Thus section 2 gives a short overview about a possible systematization of flexibility in production and existing approaches to evaluate it. A new approach which focuses on volume and mix flexibility is introduced in section 3 and then validated in section 4. The last part of this paper summarizes the main findings.

In this paper an overview on existing approaches to evaluate flexibility and a possible systematization of this domain has been given. As existing models are hard to implement in practice requirements for measuring and evaluating flexibility have been formulated. In section 3 an approach which focuses on volume and mix flexibility was introduced as these are the most important flexibility types. The validation has shown that it is very well suitable for an application in practice because input characteristics are collectable with little effort and customer requirements are taken into account.The approach provides a holistic and quantitative method to evaluate volume and mix flexibility. It is qualified for a quick ex-post analysis and gives a good insight if the system is flexible and lean enough to meet the market demand precisely. A further advantage is the branch, production concept or technology. However focusing on an easy-to-implement analysis of the current situation the approach does not provide an ex-Furthermore it is important to interpret the results before coming to a final conclusion as the duration of the chosen period under consideration for example has a sensitive influence on the outcome. In addition the flexibility indicator FLEXt should not be examined solitarily as we have argued by introducing the graph shown in figure 3.Nevertheless the results of the validation show that the approach gives a good insight on the past and current flexibility situation and that it is well-suited for an implementation in practice.