Preparatory Stage

The preparatory work is needed when a company first starts implementing a variant system. Throughout the preparatory stage, present components are coded, classified, and subsequently grouped into families. The primary step is to choose an appropriate coding system. The coding system must cover the overall spectrum of parts produced in the shop. It should be unambiguous and easy to understand. The special features that exist on the part should be clearly identified by the coding system. An existing coding system might be adopted and then modifications might be made for the specific shop. The coding of existing components might be a tedious task. Before it may be done, a thorough learning of the inventory of drawings and process plans need to be completed so that an orderly coding task might be conducted. The personnel involved in coding should be trained. They might have a precise understanding of the coding system. They should generate identical code for the same component while they work independently. Incompatible coding of components results in erroneous and redundant data in the database. The variant system utilizes a standard coding scheme as optiz, MICLASS, DCLASS or KK3, etc.

After coding is completed, part families might be formed. A family matrix is constructed for each part of family. Because of the large number of components involved, a computer must be used to help construct family matrices. The next step is to set up standard process plans for part families. In general, process plan of composite part of a typical part family is prepared (standard plans) and after that stored in a database and indexed by family matrices. In several systems, individual process plans are also stored in the database. Though, in such systems only plans for frequently produced parts are stored. The preparatory stage is a labour-intensive process. It needs a tremendous amount of effort. Whatever is prepared for shop A might be used only for shop A. However, the system structure and software can be utilized by other shops but the database must be prepared uniquely as well for each shop.