October University for Modern Sciences & ArtsFaculty of Engineering

2009

Answer all of the following questions:

Question I (8 marks)The uptime of an assembly line isunit/min., and the following:

90"/"'

q={.€=hK-

rate N Ithe

ISE 421Production System

uction

Work element Element time (min.) Must be preceded byI)34f,

6789101 123

0.20.40.70.10.30 . l t0.320.84.270.380.50.r2

;l12)

33314617r85r89ol01 1

a)-Draw the precedence diagram.b)-Use the ranked positional weight tgchnique to balance the linec)-Determine the balance delay

^ .obb

Ouestion 2 (10 malhs)A 17 station automatic transfer line has a cycle time of 0.75 min.o theprobability of breakdown for all stations is 0.01, and a repair time of 3min. The distribution of the repair time is constant. Divide the line intotwo stages separated by a buffer of capacity 5 units and determine theproduction rate of the line at that buffer capacity.

B T lr = \ . h ( b \ = + L ' '

'

B + I T n G + 1 ) ( B + 2 )

ru.'(l-r7'l - y T"r + l . h ( b ) = r J N + L - u.\(l-ru.')| .ru*' ' "

Tu (l*,

Ouestion 3 (5 marks)A 23-station transfer line has been logged for 3 days (a total of 2400 min). Duringthis timeo there were a total of 160 down time occurrences on the line. The

/

accompanying table identifies the type of down time occurrence, how manyoccurrences, and how much total time for the type of occurrence.

Type of occurrence Number ofOccurrences

Total minuteslost

Associated with stationsTool-related causes at stationsMechanical failures at stationsOther station failuresAssociated with transfer mechanism

\ 6o \661{The transfer line performs a sequence of machining operations, the longest ofwhich takes 0.50 min. The transfer mechanism takes 0.10 min. to index a partfrom one station to the next position. Assuming no parts removal when the linejams, determine the following characteristics for theilday period:a)-How many parts are produced.b)-Down time Proportion.c)-Production rate and production time.d)-Determine the frequency rate p associated with the transfer mechanismbreakdowns.

Ouestion 4 (5 marks)An eight station automated assembly line operates with an ideal cycle time of 25s.The probability of assembling a defective part at any station is 0.05, theprobability that a defective part will stop the line is 0rQ_ !. When a stop occurs, ittakes an avernge of 1 minute to replace the def6ctive part. Determine thefollowing:i-)Average production time To.ii-)The number of raw parts to be fed onto the line to produce 2000 finishedunits.iii-)Line efficiency E.V-)The number of defective assemblies produced.VI-)The number of hours required to produce 2000 finished unitg.

L= Cl2 'Tr

Ouestion 5 (6 marks)The ABC Company is planning a new product line and will build a new plant to

manufacture the parts for this product line. The product line will include 50different models. Annual production of each model is expected to be 1000 units.Each product will be assembled of 400 components. All processing of parts willbe accomplished in one factory. There are an average of six processing stepsrequired to produce each component , and each processing step takes I minute.All processing operations are performed at workstations, each of which includesa production machine and a human worker. If each workstation requires a floorspace of 250 square feeto and the factory operates one shift (2000 hr/yr),

determine (a) how many production operations, (b) how much floor space, and(c) how many workers will be required.

r34 793104 s2023 1897 8 426 78

rQ\ .tpsl' l-i^e

Ouestion 6 (6marks)A certain part is routed through six machines in a batch production plant. Thes-etupo operation, and non-operation times are given in tabre berow. beterminelruwr 4r t; Brvru t[ [aDIe DeIOW. U

nt utilization. 6-t ;;"P;F,Machine Setup time(hr.) On".u

5

3.5101.94.12.5

vI2442.5

)

34J

6

' " : i ' -

a.