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Research paper : Toward the integrated optimization of steel plate production process (K. Nishioka et al.)−108−Synthesiology - English edition Vol.5 No.2 (2012) steel by understanding the production system as a time-wise multi-scale hierarchical structure, and by linking properly each stratum via support systems. In many industries, the shortening of the time required for manufacturing is an essential element for the development of diversified value-added products and manufacturing them as competitive products. For example, even in the pharmaceutical field that appears to be at the extreme opposite end of the spectrum, we are now in an age where the competitive edge of products is determined by price and speed. In the past, in the field of pharmaceutical products, having differential products protected by patents gave a company its competitive edge. However, due to the diffusion of generic products, having the capability to produce drugs of various kinds as price competitive products is becoming an important management issue. For example, tablets are manufactured into a wide variety of products using a series of equipment and manufacturing processes for mixing, granulation, sieving, mixing, tableting and coating.[31] and these processes are controlled elaborately by computers as it is with the iron and steel manufacturing processes. In other words, the industry has many issues similar to the steel industry also in the fact that efforts to meet various products are required also in terms of its process structure and the approach proposed in this paper of developing a model is considered to enable horizontal deployment in many process industries including pharmaceuticals.In Japanese manufacturing companies, a succession of technical staff has steadily taken charge of innovation in manufacturing technologies and production control on the shop floor. The manufacturing knowledge acquired during the course of such innovative efforts is expected to be documented and published as educational materials and also engineering as a practical science is expected to be systematized as part of academic fields.[32] It goes without saying that to realize the integrated optimization on the manufacturing shop floor, it is necessary to understand the phenomena at each stratum extending from the micro to macro level, to develop models, and compare them within a developed framework against best practices in other business sectors and companies. The multi-scale hierarchically structured model for production control proposed in this paper was developed based on the knowledge of field engineers obtained from their wide and in-depth OJT throughout their career, and this paper strongly suggests the necessity of systematizing manufacturing knowledge from industries.AcknowledgementsThis research was conducted with the support of Grants-in-Aid for Scientific Research – Basic Research (B) 17330082. We would like to express our gratitude to Messrs. Akitoshi SEIKE, Takahiro FUJIMOTO, Jyunjiro SHINTAKU, and Kenichi KUWASHIMA for their invaluable advice on this research from an academic perspective. We would also like to express our gratitude to Messrs. Akio MIMURA, Shoji MUNEOKA, Mutsumi OHJI, Okitsugu MANTANI and Keiji ICHINOSE for their guidance and support.NotesNote 1) In the actual production, because manufacturing is conducted in combination with more than one product group, the bottleneck processes change sequentially and situations very often occur where the bottleneck process is different from the one particular to the product group concerned. Therefore, the past records of rolling process efficiency observed in actual production vary, unlike the particular integrated efficiency recorded in the case of continued manufacturing of the same product group, in every term for which records were aggregated as influenced by the combination of production permutation that varies in every term. In this efficiency model, this problem was avoided by defining product groups after extracting the factors affecting the processing efficiency of each process so that the efficiency of actual rolling processes as a whole distributes the specific integrated efficiency as the median. In terms of the rolling processes as a whole, irrespective of the production permutation, the product group sizes were adjusted so that the difference between the past record of integrated efficiency and the integrated efficiency specific to the product group was balanced out, thus succeeding in producing highly accurate estimates of the overall efficiency of rolling processes compared with conventional models.Note 2) The production of steel plates is characterized by receiving orders for various products (products of the same specification in one order are about 3 t), manufacturing them in lots (condition of the same steelmaking: min. 300 t, but considering productivity, desirably over 2,000 t) and delivering products in the unit of a lot (for the same customer, delivery date, transportation means). The delivery date is specified for the same shipment lot, but as requested by the customer, orders of various products are contained in one shipment lot, and the manufacturing lot does not generally agree with the shipment lot. Therefore, even though the timing to start rolling is determined by counting backward the manufacturing lead time set from the delivery date, variation is inevitable when grouping products in a manufacturing lot. Note 3) With the help of the existing correlation between the number of processes to be passed in the finishing processes and the manufacturing lead time, the following method was adopted: (1) after having estimated the completion

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