Group Technology
Group technology is a manufacturing philosophy approach in which similar parts are indentified and grouped together in order to take advantage of their similarities in design and production. Similarities among parts permit them to be classified into part families.
Similiar parts are arranged into part families ,where each part family possesses similiar design and.or manufacturing characterstics.
The advantage of Group technology can be divided into three groups:
- Engineering
- Manufacturing
- Process planning
Group Technology in Engineering:- The major advantage of GT for engineering come in cost avoidance, because engineers can now quickly and easily search the database for components that either presently exist or can be used with slight modification, rather than issuing new part numbers. Another engineering advantage is the standardization of design. By recalling a family of parts and comparing productivity costs, the designer can design to least-cost methods. This means the entire engineering department can standardize on corner radii, tolerances, chamfers, counter bores, surface finishes and so on.
Group Technology in Manufacturing:-Studies have shown that a part on a machine tool 5% of the total time it is in the shop during the remaining 95% of the time, it is being moved from one department to another or merely waiting in a warehouse, bin, pallet or some familiar site. Furthermore, of the 5% of the time that it is on a machine tool, it is in contact with the cutting tool only 30% of that time. The remaining 70% of the 5% is spent in tool changing clamping, unclamping, measuring and so on. In short, the part contact time with the cutter is only 1.5% (5% X 30%) of its time in the shop. Higher production rates have usually meant higher r.p.m. , better inserts, or higher feeds, but that is attacking only 1.5% of the problem. The real problem is with the part out in the shop on a pallet. It is called work-in-progress (WIP) inventory.
Group technology (GT) is concerned more with the 95% of the time the part is waiting than the 5% of the part is on a machine tool. GT attacks this problem by grouping machine tools into work cells, rather than in the traditional shop layout of locating all lathes in one department, the mills in another, drill presses in another and so on.
Process planning:- There is much interest by manufacturing firms in automating the task of process planning using computer-aided process planning systems. The shop trained people who are familiar with the details of machining and other processes are gradually retiring, and these people will be unavailable in the future to do process planning. An alternative way of accomplishing this function is needed, and CAPP systems are providing this alternative. CAPP is usually considered to be part of computer aided manufacturing (CAM). However, this tends imply that CAM is a standalone system. In fact, a synergy results when CAM is combined with CAD to create a CAD/CAM system. In such a system, CAPP becomes the direct connection between design and manufacturing.
Advantages:
Advantages:
- Better lead times gives a fast response and more reliable delivery.
- Work in progress and finished stock level are reduced.
- Output is improved because of improved resource utilisation.
- Less materials handling is needed.
- Better space utilisation
Disadvantages of group technology:-
Although in Group Technology ,some variation is there os is absolutely essential for the automated factories of the future ,most companies are reluctant to incorporate the concept into their organisation.
The reasons advanced are that the implementaion is expensive ,slow and tedious ;a difficult learning curve is involved and people are complacent and satisfied with the status.
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