Multi Class Coding System

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Parts in the medium production quantity range are usually made in batches

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Disadvantages of batch production: Downtime for changeovers High inventory carrying costs GT minimizes these disadvantages by recognizing the talthough the parts are different, there are groups of parts that possess similarities GT exploits the part similarities by utilizing similar processes and tooling to produce them GT can be implemented by manual or automated techniques When automated, the term flexible manufacturing system is often applied

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Hierarchical structure, known as a monocode, in which the interpretation of each successive symbol depends on the value of the preceding symbols

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Chain-type structure, known as a polycode, in which the interpretation of each symbol in the sequence is always the same; it does not depend on the value of preceding symbols

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Mixed-mode structure, which is a hybrid of the two previous codes

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MultiClass (OIR: Organization for Industrial Research), hierarchical or decision-tree coding structure

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First 18 digits of the Multiclass Classification and Coding System

Developed in 1970, encoding computer System  The first four digits give shape attributes and the remaining eight machining, dimensions, tolerances and material.  Allows the encoding of a wide variety of products, parts, assemblies, machines, tools, for each group using a suitable coding structure

Code up to 30 digits, of which 18 are standardized and mandatory. Can be used for different types of products: machining, sheet, electronic purchasing, assemblies, subassemblies, machines and tools. Hierarchical structure.

This system was standardized by the Institute of Metal Classification System and was developed by TNO. (The Netherlands Organization for Research Scientific Applications). This system was created to the design and manufacturing functions, including: Standardization of Engineering Drawings.

Drawing Recovery in terms of a number of lassification.  Standardization of process routes.  Planning in process automation.Selection of parts to be processed according to the machining processes.  Investment analysis of machine tools and more. 

This system comprises two main sections: The first is made up of 12 to 30 digits of manufacturing characteristics used to classify and engineering parts such as, materials, tolerances, dimensions etc. The first 4digits of this section used to represent the general shapes of the main elements and its position.

Los following four digits provide information dimensional. the 9 and 1 0 digit tolerances. Los contains information about 11 and 12 contain information about the property of machinability and metals.

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Technology groups is an approach to manufacturing which are identified andgrouped similar parts to take advantage of their similarities in design andproduction. It is also known as group technology and is implemented through automatedmanual techniques. When using automation usually uses the term flexiblemanufacturing system.

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Parts classification and coding This method of grouping parts into families involves an examination of the individual design and/or manufacturing attributes of each part. The attributes of the part are uniquely identified by means of a code number. This classification and coding may be carried out on the entire list of active parts of the firm, or a sampling process may be used to establish the part families. For example, parts produced in the shop during a certain given time period could be examined to identify part family categories. The trouble with any sampling procedure is the risk that the sample may be unrepresentative of the entire population. However, this risk may be worth taking, when compared to the relatively enormous task of coding all the company’s parts.

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Parts classification and coding systems divide themselves into one of three general categories: 1. Systems based on part design attributes 2. Systems based on part manufacturing attributes 3. Systems based on both design and manufacturing attributes

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Group technology machine cells The traditional view of group technology includes the concept of GT machine cells-groups of machines arranged to produce similar part families. This cellular arrangement of production equipment is designed to achieve an efficient workflow within the cell. It also results in labor and machine specialization for the particular part families produced by the cell. Part families are defined by the fact that their members have similar design and manufacturing attributes. The composite part concept takes this part family definition to its logical conclusion. It conceives of a hypothetical part that represents all of the design and corresponding manufacturing attributes possessed by the various individuals in the family. Such a hypothetical part is illustrated in the following Figure.

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Benefits of group technology Although group technology is expected to be an important principle in future production plants, it has not yet achieved the widespread application, which might be expected. There are several reasons for this. First, there is the problem of rearranging the machines in the plant into GT cells. Second, there is the problem of identifying part families among the many components produced in the plant. Finally, it is common for companies to encounter a general resistance among its operating personnel when changeover to a new system is contemplated.