Group Technology and Cellular Manufacturing
Parts Classification and Coding
Features of Parts Classification and Coding Systems
Examples of Parts Classification and Coding Systems
Production Flow Analysis
Composite Part Concept
Machine Cell Design
Application Considerations in Group Technology
Applications of Group Technology
Survey of Industry Practice
Quantitative Analysis in Cellular Manufacturing
Grouping Parts and Machines by Rank Order Clustering
Arranging Machines in a GT Cell
Batch manufacturing is estimated to be the most common form of production in the United States, constituting more than 50% of total manufacturing activity. There is a growing need to make hatch manufacturing more efficient and productive. In addition, there is an increasing trend toward achieving a higher level of integration between the design and manufacturing functions in a firm. An approach directed at both of these objectives is group technology (GT).
Group technology is a manufacturing philosophy in which similar parts are identified and grouped together to take advantage of their similarities in design and production. Similar parts are arranged into part/amities. where each part family possesses similar design and/or manufacturing characteristics. for example, a plant producing 10,000 different part numbers may be able 10 group the vast majority of these parts into 3040 distinct families It is reasonable to believe that the processing of each member of a given family is similar. and this should result in manufacturing efficiencies. The efficiencies are generally achieved by arranging the production equipment into machine groups, or cells, to facilitate work flow. Grouping the production equipment into machine cells, where each cell specializes in the production of a part family. is called cellular manufacturing. Cellular manufacturing is an example of mixed model production (Section 13.2.4). The origins of group technology and cellular production can be traced to around 1925.
The plant currently uses traditional batch production and a process type layout
(Section 1.1.2), and this results in much material handling effort, high in process inventory, lead long manufacturing lead times .
The parts can be grouped Into part families. This is a necessary condition, Each machine cell is designed to produce a given part family, or limited collection of part families, so it must be possible to group parts made in the plant into families. However, it would be unusual to find a mid-volume production plant in which parts could not he grouped into part families
There are two major tasks that a company must undertake when it implements group technology. These two tasks represent significant obstacles to the application of GT.
1 Identifying the part families. If the plant makes 10,000 different parts, reviewing all of the part drawings and grouping the parts into families is a substantial task that consumes a significant amount of time.
Rearranging production machines into machine cells. It is time consuming and costly 10 plan and accomplish this rearrangement, and the machines are not producing during the changeover
Group technology offers substantial benefits to companies that have the perseverance to implement it. The benefits include:
GT promotes standardization of tooling, fixturing. and setups.
Material handling is reduced because parts are moved within a machine cell rather than within the entire factory.
Process planning and production scheduling are simplified
Setup times are reduced, resulting in lower manufacturing lead times.
Work-in-process is reduced.
Worker satisfaction usually improves when workers collaborate in a OT cell.
Higher quality work is accomplished using group technology.
In this chapter, we discuss group technology, cellular manufacturing, and several related topics. Let us begin by defining an underlying concept of group technology: part families.