Group Technology
Group Technology
Group technology is an approach to organising manufacture which can be applied in any industry (machining, welding, foundry, press work, forging, plastic moulding, etc.) where small-batch variety production is used.
The basic approach enables all aspects of manufacturing, from design, through estimating and planning, to production, to be rationalised. It forms the basis for the development of computer-aided procedures and flexible automation.
The group of similar parts is known as part family and the group of machineries used to process an individual part family is known as machine cell. It is not necessary for each part of a part family to be processed by every machine of corresponding machine cell. This type of manufacturing in which a part family is produced by a machine cell is known as cellular manufacturing.
The manufacturing efficiencies are generally increased by employing GT because the required operations may be confined to only a small cell and thus avoiding the need for transportation of in-process parts.
Group technology is a manufacturing philosophy or principle whose basic concept is to identify and bring together related or similar parts and processes, to take advantage of the similarities which exist, during all stages of design and manufacture.
If parts can be classified into families, and machines arranged into groups, then the handling of parts during manufacture can be easily done by robot.
It must be understood that there exists relationship between finished products and the parts from which they are made. While assemblies may bear little relation to each other, the subassemblies from which they are constructed will exhibit some like features. By exploiting the similarities which exist among such a population of parts, group technology sets out to reduce the time and cost of manufacture.
The main theme is thus to identify somehow from the large variety of parts those families which require similar manufacturing operations. Cells are created to manufacture defined types and size ranges of parts.
Groups of machines, chosen for each family are situated together in a group layout, in such a way that parts flow from one machine to the next in sequence of operation. It is not-necessary for every part to visit each machine, but the machines in a cell should ideally be capable of carrying out all the operations required in the family.
It may be remembered that in a functional layout, all like machines are grouped at one place and thus a product has to move a lot of distance in a zig-zag manner. But in a cell layout, various machines are arranged so that product flows from one machine to the next in sequence.
Advantages of Group Technology:
The advantages of group technology are:
(i) Better lead times result in fast response and more reliable delivery.
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(ii) Material handling is reduced considerably.
(iii) Robots can be easily used for material handling.
(iv) Better space utilisation.
(v) Smaller variety of tools, jigs and fixtures.
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(vi) Improved quality and less scrap.
(vii) Output is improved due to improved resource utilisation.
(viii) Work in progress and finished stock levels are reduced.
(ix) Simplified estimating, accounting and work management.
(x) Improved plant replacement decisions.
(xi) Improved job satisfaction, morale and communication.
(xii) Reduced product design variety.
Disadvantages of Group Technology:
The disadvantages of group technology are:
(i) Additional cost of implementation of this system.
(ii) Rate of change in product range and mix.
(iii) Difficulties with out-of-cell operations.
(iv) Coexistence with non-cellular systems.
Uses of Group Technology:
Survey of product and use of group technology:
Group technology technique can be conveniently followed using a classification system. In any assembly, a variety of parts exist. These varieties of parts can be-segregated in three broad areas, viz.
(i) Standard and proprietary parts (like nuts, bolts, screws, keys, washers, etc.)
(ii) Similar parts (like shafts, gears, bearings, levers, etc.)
(iii) Product specific parts (like gear box, bed, saddle, etc.)
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