自动化课后答案ch18 cellular mfg3esi.docx

1、自动化课后答案ch18 cellular mfg3esiChapter 18CELLULAR MANUFACTURINGREVIEW QUESTIONS18.1What is group technology?Answer: As defined in the text, group technology is a manufacturing philosophy in which similar parts are identified and grouped together to take advantage of their similarities in design and pro

2、duction.18.2What is cellular manufacturing?Answer: As defined in the text, 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 gro

3、up of families.18.3What are the production conditions under which group technology and cellular manufacturing are most applicable?Answer: The conditions identified in the text are (1) the plant currently uses traditional batch production and a process type layout, and this results in much material h

4、andling effort, high in-process inventory, and long manufacturing lead times; and (2) the parts can be grouped into part families. 18.4What are the two major tasks that a company must undertake when it implements group technology?Answer: The two major tasks are (1) identifying the part families and

5、(2) rearranging production machines into machine cells. 18.5What is a part family?Answer: As defined in the text, a part family is a collection of parts that are similar either because of geometric shape and size or because similar processing steps are required in their manufacture.18.6What are the

6、three methods for solving the problem of grouping parts into part families?Answer: The three methods are (1) visual inspection, (2) parts classification and coding, and (3) production flow analysis.18.7What is the difference between a hierarchical structure and a chain-type structure in a classifica

7、tion and coding scheme?Answer: In a hierarchical structure, also known as a monocode, the interpretation of each successive symbol depends on the value of the preceding symbols. In a chain-type structure, also known as a polycode, the interpretation of each symbol in the sequence is always the same;

8、 it does not depend on the value of preceding symbols.18.8What is production flow analysis?Answer: As defined in the text, production flow analysis is a method for identifying part families and associated machine groupings that uses the information contained on production route sheets rather than pa

9、rt drawings. Workparts with identical or similar routings are grouped into part families.18.9What are the typical objectives when implementing cellular manufacturing?Answer: As enumerated in the text, the objectives are to (1) shorten manufacturing lead times, by reducing setup, workpart handling, w

10、aiting times, and batch sizes; (2) reduce work-in-process inventory; (3) improve quality; (4) simplify production scheduling; and (5) reduce setup times. 18.10What is the composite part concept, as the term is applied in group technology?Answer: The composite part concept is based on part families.

11、It conceives of a hypothetical part for a given family that includes all of the design and manufacturing attributes of the family. In general, an individual part in the family will have some of the features that characterize the family, but not all of them. The composite part possesses all of the fe

12、atures.18.11What are the four common GT cell configurations, as identified in the text?Answer: The four GT cell configurations listed in the text are (1) single machine cell, (2) group machine cell with manual handling, (3) group machine cell with semiintegrated handling, and (4) flexible manufactur

13、ing cell or flexible manufacturing system.18.12What is the key machine concept in cellular manufacturing?Answer: The key machine concept acknowledges that there is typically a certain machine in a cell that is more expensive to operate than the other machines or that performs certain critical operat

14、ions. This machine is referred to as the key machine. It is important that the utilization of this key machine be high, even if it means that the other machines in the cell have relatively low utilizations. The other machines are referred to as supporting machines, and they should be organized in th

15、e cell to keep the key machine busy.18.13What is the difference between a virtual machine cell and a formal machine cell?Answer: Virtual machine cells involve the creation of part families and the dedication of equipment to the manufacture of these part families, but without the physical rearrangeme

16、nt of machines into formal cells. The machines in the virtual cell remain in their original locations in the factory. Formal machine cells represent the conventional GT approach in which a group of dissimilar machines are physically relocated into a cell that is dedicated to the production of one or

17、 a limited set of part.18.14What is the principal application of group technology in product design?Answer: As indicated in the text, the principal application of GT in design is to implement a design retrieval system that reduces part proliferation.18.15What is the application of the rank order clu

18、stering?Answer: The application of the rank order clustering in GT is grouping machines into cells based on the part-machine incidence matrix, which in turn is based on route sheets.PROBLEMSParts Classification and Coding18.1Develop the form code (first five digits) in the Opitz System for the part

19、illustrated in Figure P18.1.Solution: L/D = 0.06/0.80 = 0.075Digit 1 = 0External shape = smoothDigit 2 = 0Internal shape = smooth, no shape elementDigit 3 = 1Plane surface machining = noneDigit 4 = 0Auxiliary holes, etc., = noneDigit 5 = 0Form code in Opitz system = 0010018.2Develop the form code (f

20、irst five digits) in the Opitz System for the part illustrated in Figure P18.2.Solution: L/D = 2.5/1.5 = 1.667Digit 1 = 1External shape = stepped, one holeDigit 2 = 1Internal shape = smooth holeDigit 3 = 1Plane surface machining = noneDigit 4 = 0Auxiliary holes, etc., = noneDigit 5 = 0Form code in O

21、pitz system = 1110018.3Develop the form code (first five digits) in the Opitz System for the part illustrated in Figure P18.3.Solution: L/D = 121/36 = 3.361Digit 1 = 2External shape = stepped both ends with functional grooveDigit 2 = 6Internal shape = no holeDigit 3 = 0Plane surface machining = none

22、Digit 4 = 0Auxiliary holes and gear teeth = spur gear.Digit 5 = 6Form code in Optiz = 26006Rank Order Clustering18.4Apply the rank order clustering technique to the part-machine incidence matrix in the following table to identify logical part families and machine groups. Parts are identified by lett

23、ers, and machines are identified numerically.PartsMachinesABCDE1121131141151Solution: Step 1Step 2ABCDERankABCDE1123112114113111411411321151551Rank13425Step 3Step 4ADBCERankADBCE3111311112114114512115411513211Part families and machine groups: I = (A, D) and (3,1,5), II = (B, C, E) and (4, 2).18.5App

24、ly the rank order clustering technique to the part-machine incidence matrix in the following table to identify logical part families and machine groups. Parts are identified by letters, and machines are identified numerically.PartsMachinesABCDEF1112113114115116111Solution: Step 1Step 2ABCDEFRankABCD

25、EF11123112116111311151141156111511341161114211Rank125436Step 3ABEDCFRankPart families and machine groups:3111 I = (A, B, E) and (3, 1, 5)1112 II = (D, C, F) and (6, 4, 2)5113611144115211618.6Apply the rank order clustering technique to the part-machine incidence matrix in the following table to identify logical part families and machine groups. Parts are identified by letters, and machines are identified numerically.PartsMachinesABCDEFGHI11121131114111511611711811Solution: Step 1Step 2ABCDEFGHIRankABCDEFGHI1112711211411131115411141113211511731116118811711151181