Msa University - Production Systems Final Exam 2009

OctoberUniversityfor Modern Sciences & Arts Facultyof Engineering

ISE 421 ProductionSystem

2009

q={

Answerall of the followingquestions: QuestionI (8 marks) The uptime of an assemblyline is 90"/"' the unit/min.,and the following: Work element I ) 3 4

Element time (min.)

0.2 0.4 0 .7 0 .1 0.3 0.lt 0.32 0.8 4.27 0.38 0.5

f,

6 7 8 9 10 11 23

.€=hK-

uction rate N I Must be precededby

; l12 )

3 3 314 617r8 5r8 9ol0 11

0.r2

a)-Draw the precedencediagram. b)-Usethe ranked positional weight tgchnique to balance the line c)-Determinethe balance delay ^ .obb Ouestion 2 (10 malhs) A 17 station automatic transfer line has a cycle time of 0.75 min.o the probability of breakdown for all stations is 0.01, and a repair time of 3 min. The distribution of the repair time is constant. Divide the line into two stages separated by a buffer of capacity 5 units and determine the production rate of the line at that buffer capacity. r=\.h(b\=

B

B+I

T +L''

l'

TnG+1)(B+2)

l-y

r+l.h(b)=rJN+L-'

| .ru*'

"

T" ru.'(l-r7' Tu (l*,

u.\(l-ru.')

Ouestion3 (5 marks) A 23-stationtransfer line has beenloggedfor 3 days(a total of 2400min). During this timeotherewere a total of 160down time occurrences on the line. The

accompanying table identifiesthe type of down time occurrence,how many occurrences, and how much total time for the type of occurrence. Type of occurrence

Number of Occurrences

Associated with stations Tool-related causesat stations Mechanical failures at stations Other station failures Associatedwith transfer mechanism

r34 104 23 7 26

/

Total minutes lost

793 s20 189 4 78

8

\ 6o

\661{

of machiningoperations,the longestof The transfer line performsa sequence which takes0.50min. The transfer mechanismtakes0.10min. to index a part from onestationto the next position.Assumingno parts removalwhen the line jams,determinethe following characteristicsfor theilday period: a)-Howmany parts are produced. b)-Downtime Proportion. c)-Productionrate and productiontime. with the transfer mechanism d)-Determinethe frequencyrate p associated breakdowns. Ouestion 4 (5 marks) An eight station automated assemblyline operateswith an ideal cycle time of 25s. The probability of assembling a defective part at any station is 0.05, the probability that a defective part will stop the line is 0rQ_ !. When a stop occurs, it takes an avernge of 1 minute to replace the def6ctive part. Determine the following: i-)Average production time To. ii-)The number of raw parts to be fed onto the line to produce 2000 finished units. iii-)Line efficiency E. V-)The number of defective assembliesproduced. VI-)The number of hours required to produce 2000 finished unitg.

L =C l 2' T r

(6 marks) Ouestion 5 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 50 different models. Annual production of each model is expectedto be 1000 units. Each product will be assembledof 400 components.All processing of parts will be accomplished in one factory. There are an average of six processing steps required to produce each component , and each processing step takes I minute. All processingoperations are performed at workstations, each of which includes a production machine and a human worker. If each workstation requires a floor space 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.

rQ\

.tpsl' l-i^e

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

nt utilization. 6-t

Setup time(hr.)

;;"P;F,

On".u 5

)

3 4 J

6

3.5 10 1.9 4.1 2.5

I 2 4 4 2.5 '":i'

-

v