Lec2 GT.pptx. grouptechnology definition and application
- 1. الحمد اللطيف عبد جامعة – مروي الهندسة كلية القسم : الصناعية الهندسة المستوى : الخامس المقرر : المرن التصنيع نظم
- 2. FMS Lec. 2 group Technology Ref; Grover ch. 18 Content Part Families and Machine Groups 1 What is a Part Family? 2 Intuitive Grouping 3 Parts Classification and Coding 4 Production Flow Analysis Cellular Manufacturing 1 Composite Part Concept 2 Machine Cell Design Applications of Group Technology
- 3. Group technology 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 families, where each part family possesses similar design and/or manufacturing characteristics. Cellular manufacturing. Organizing the production equipment into machine cells, where each cell specializes in the production of a part family
- 4. GT application Conditions that make GT application is most appropriate: The plant currently uses traditional batch production and a process-type layout, which results in: much material handling, high in-process inventory, and long manufacturing lead times. It is possible to group the parts into part families. In the typical mid-volume production plant, most of the parts can be grouped into part families.
- 5. What are the major tasks in implementing GT 1. Identifying the part families. 2. Rearranging production machines into machine cells. These tasks are costly and time consuming and therefore good planning is necessary.
- 6. Benefits of GT and cellular manufacturing GT promotes standardization of tooling, fixturing, and setups. Material handling is reduced , the distances within a machine cell are much shorter. 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 GT cell. Higher quality work is accomplished.
- 7. Part Families and Machine Groups What is a Part Family A part family is a collection of parts that are similar either in geometric shape and size or in the processing steps required in their manufacture. The parts within a family are different, but their similarities are enough for a part to be members of the part family.
- 8. Part Families Figure 18.1 Two parts of identical shape and size but different manufacturing requirements: (a) 1,000,000 pc/yr, tolerance = {0.010 in., material = 1015 CR steel, nickel plate; and (b) (b) 100 pc/yr, tolerance = {0.001 in., material = 18-8 stainless steel.
- 9. Part Families Figure 18.2 A family of parts with similar manufacturing process requirements but different design attributes. All parts are machined from cylindrical stock by turning; some parts require drilling and/or milling.
- 10. Part Families Figures 18.3 and 18.4 shows different configuration of machine shop. Figure 18.3 shows a process-type plant layout for batch production in a machine shop. This results in much material handling, large in-process inventories, many setups, long lead times, and high cost. Figure 18.4 shows a production shop of equivalent capacity that has its machines arranged into cells. Each cell is organized to specialize in the production of a part family. The problem of grouping the parts into families.
- 11. Figure 18.3 Process-type plant layout. (Key: Turn = turning, Mill = milling, Drll = drilling, Grnd = grinding, Asby = assembly, Man = manual operation; arrows indicate work flow through plant, and dashed lines indicate separation of machines into departments.)
- 12. Figure 18.4 Group-technology layout. (Key: Turn = turning, Mill = milling, Drll = drilling, Grnd = grinding, Asby = assembly, Man = manual operation; arrows indicate work flow in machine cells.)
- 13. Grouping the parts into families. Three methods: (1) intuitive grouping, (2) parts classification and coding, and (3) production flow analysis.
- 14. Intuitive Grouping Also known as the visual inspection method, is the least sophisticated and least expensive method. Is the most common method that companies use to identify part families. Intuitive grouping involves the classification of parts into families by experienced technical staff. The technical staff examine the physical parts or their photographs. The parts arranged in groups having similar feature.
- 15. Intuitive Grouping Features: (1) design attributes, which are concerned with part characteristics such as geometry, size, and material, and (2) manufacturing attributes, which consider the processing steps required to make a part.
- 17. Parts Classification and Coding Reasons for using a coding scheme include: Design retrieval. Automated process planning. Machine cell design.
- 18. Parts Classification and Coding (categories) The principal functional areas that would use a parts classification and coding system are design and manufacturing. Accordingly, parts classification and coding systems fall into one of three categories: (1) systems based on part design attributes, (2) systems based on part manufacturing attributes, and (3) systems based on both design and manufacturing features.
- 19. Parts Classification and Coding (Symbol meaning in code) there are three structures used in classification and coding schemes: (1) Hierarchical structure (monocode) in which the interpretation of each successive symbol depends on the values of the preceding symbols (2) Chain-type structure, (polycode) in which the interpretation of each symbol in the sequence is always the same; not dependent on the symbols, and (3) Mixed-mode structure, a hybrid of (1) & (2) coding schemes.
- 20. Parts Classification and Coding (Symbol meaning in code) The advantage of the hierarchical structure is that in general more information can be included in a code of a given number of digits.: E.g. code 15 and 25 the 5 have different meaning in Hierarchical structure where as have same meaning in Chain- type structure. The number of digits in the code can range between 6 and 30. If code include design and manufacturing data range 20 to 30 A number of parts classification and coding systems are described in the literature. Also a number of commercial packages were developed. Selection is company’s decision.
- 21. Production Flow Analysis Production flow analysis (PFA) is an approach to part family identification and machine cell formation. Uses information from production route sheets.
- 22. Production Flow Analysis The procedure in PFA consists of the following steps: 1. Data collection. The data needed in the analysis are part number and operation sequence, 2. Sortation of process routings. the parts are arranged into groups according to the similarity of their process routings. To facilitate this step, all operations or machines included in the shop are reduced to code numbers table 18.2. sortation arrange parts in packs or group of parts. 3. PFA chart. The processes used for each pack are then displayed in a PFA chart table 18.3. 4. Cluster analysis From the pattern of data in the PFA chart, groups are identified and rearranged into a new pattern with similar machine sequences.
- 25. Production Flow Analysis The weakness of production flow analysis is that the data used in the technique are derived from existing production route sheets.
- 26. Cellular Manufacturing Cellular manufacturing is an application of group technology in which dissimilar machines or processes have been aggregated into cells, each of which is dedicated to the production of a part or product family, or a limited group of families.
- 27. Cellular Manufacturing Typical objectives in cellular manufacturing:- 1. To shorten manufacturing lead times 2. To reduce work-in-process inventory. 3. To improve quality. 4. To simplify production scheduling.. 5. To reduce setup times.
- 28. Cellular Manufacturing A manufacturing cell consists of dissimilar equipment that is organized to produce similar parts (part families). Two aspects of cellular manufacturing are considered in this section: 1. The composite part concept and 2. Machine cell design.
- 29. Composite Part Concept The composite part for a given family is a hypothetical part that includes all of the design and manufacturing attributes of the family. There is always a correlation between part design features and the production operations required to generate those features. Round holes are made by drilling, cylindrical shapes are made by turning, flat surfaces by milling, and so on. A production cell designed for the part family would include those machines required to make the composite part. The cell would be designed to allow for size variations within the family as well as feature variations
- 30. Composite Part Concept Figure 18.5 and Table 18.5 illustrate the concept Figure 18.5 Composite part concept: (a) the composite part for a family of machined rotational parts, and (b) the individual features of the composite part. See Table 18.5 for key to individual features and corresponding manufacturing operations.
- 32. Machine Cell Design The cell design determines to a great degree the performance of the cell. Types of Machine Cells.:- 1. Assembly cells, which produce families of subassemblies or products. 2. Part cells, which process families of parts.
- 33. Machine Cell Design Machine cells for part family production can be classified according to the number of machines and the degree to which the material flow is mechanized between machines. Four common GT cell configurations are : 1. single-machine cell, 2. group-machine cell with manual handling, 3. group-machine cell with semi-integrated handling, and 4. Flexible manufacturing cell or flexible manufacturing system.
- 34. Type of Machine Cell single-machine cell consists of one machine plus supporting fixtures and tooling. Attributes can made on basic processes (e.g. lathe, milling) group-machine cell with manual handling : is an arrangement of more than one machine used collectively to produce one or more part families, no mechanized material handling. The machines are often organized in a U shape layout. Figure 18.6. group-machine cell with semi-integrated handling uses a mechanized handling system, such as a conveyor, to move parts between machines in the cell. Flexible manufacturing system (FMS) combines a fully integrated material handling system with automated processing stations.
- 35. Type of Machine Cell Figure 18.6 Machine cell with manual handling between machines. A U-shaped machine layout is shown. (Key: Proc = processing operation (mill, turn, etc.), Man = manual operation; arrows indicate work flow.)
- 36. Machine Cell Layouts. Various layouts are used in GT cells.: 1. The U-shape in Figure 18.6 is a popular configuration in cellular manufacturing. Other GT layouts include 2. In-line, 3. Loop, and 4. Rectangular, shown in Figure 18.7 for the case of semi-integrated handling. Appropriate cell layout depends on the routings of parts produced in the cell.
- 38. Figure 18.7 Machine cells with semi-integrated handling: (a) in-line layout, (b) loop layout, and (c) rectangular layout. (Key: “Proc” = processing operation (mill, turn, etc.), “Man” = manual operation; arrows indicate work flow.)
- 39. Machine Cell Layouts. Four types of part movement: 1. repeat operation does not move. 2. in-sequence move forward from current to immediate neighbor. 3. bypassing move 4. backtracking move When the application consists exclusively of in-sequence moves, an in-line layout is appropriate. A U-shaped layout also works well here and has the advantage of closer interaction among the workers in the cell.
- 40. Machine Cell Layouts. When the application includes repeated operations, multiple stations (machines) are often required. For cells requiring bypassing moves, the U-shape layout is appropriate. When backtracking moves are needed, a loop or rectangular layout allows recirculation of parts within the cell.
- 41. Figure 18.8 Four types of part moves in a mixed-model production system. The forward flow of work is from left to right.
- 42. Machine Cell Layouts. Key Machine Concept. Is a machine in a cell (or perhaps more than one machine in a large cell) that is more expensive to operate than the other machines or that performs certain critical operations in the plant. It is important that the utilization of this key machine be high,
- 43. Applications of Group Technology “manufacturing philosophy.” GT is not a particular technique. It employs some tools and techniques for its implementation. Various applications ; manufacturing and design are important applications.
- 44. GT Manufacturing Applications. There are three ways in which group-technology principles can be applied in manufacturing:- 1. Informal scheduling and routing of similar parts through selected machines. setup advantages, but no formal part families are defined. 2. Virtual machine cells. involves the creation of part families and dedication of equipment to the manufacture of these part families, no physical arrangement. 3. Formal machine cells. a group of dissimilar machines are physically relocated into a cell that is dedicated to the production of one or a limited set of part families
- 45. GT Manufacturing Applications. Other GT applications in manufacturing include: 1. process planning, 2. family tooling, modular fixture, and 3. numerical control (NC) part programs Parametric programming .
- 46. GT Product Design Applications. The application of group technology in product design is principally for design retrieval systems. Other design applications of group technology involve: 2. Simplification and 3. Standardization of design parameters such as tolerances, inside radii on corners, chamfer sizes on outside edges, hole sizes, and thread sizes.