65
PRODUCTION ACTIVITY CONTROL
CHAPTER 6
ANSWERS TO PROBLEMS
6.2
Queue at work center A = 25
×
60
=
1500
minutes
6.4
Queue at work center A = 40
×
60
=
2400
minutes
66
6.6
DAYS
6.8 Q
=
100 units
SU
A
=
50 minutes
PART C
6.7
67
6.9
MLT before overlapping.
MLT after overlapping.
6.14
Period
1 2 3 4
Total
68
6.15
6.16
Period 1 2 3 4 5
Total
Job
Process
time
(days)
Arrival
date
Due
date
Operation
due
date
Sequencing rule
FCFS
EDD
ODD
SPT
69
6.17
6.18
Critical Ratio = Actual time remaining
Lead time remaining
Job
Work center 10 Work center 20
Start
day
Stop
day
Start
day
Stop day
70
MULTIPLE CHOICE QUESTIONS
1. A production environment in which each unit or a small group of units is managed by a
process created especially for that purpose is called
a. Intermittent
b. Job shop
c. Project
d. Flow
2
. Planning the flow of work requires production activity control to:
I
. Be sure the material needed is available.
II
. Be sure the tooling needed is available.
III
. Schedule the start and stop dates at each work center.
IV. Advise the plant supervisor of future orders.
a
. all of the above
b
. I, II and III
c
. I, II and IV
d
. II, III and IV
e
. I, III and IV
3
. The activities of production activity control can be classified as:
I
. Planning.
II
. Implementation.
III
. Control.
IV. Process control.
a
. I, II and III
b
. I, II and IV
c
. II, III and IV
d
. I, III and IV
e
. all of the above
4
. Work authorization can be classified under the function of:
a
. planning
b
.
scheduling
c
. implementation
d
. load leveling
e
. control
5
. Which of the following are characteristics of intermittent manufacturing?
I
. Work centers are arranged according to the routing.
II
. Work centers are dedicated to producing a limited range of similar products.
III
. Work flow through the shop is not constant.
IV. Throughput times are generally high.
a
. I and II
b
. I and III
c
. I and IV
d
. II and III
e
. III and IV
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6
. Which of the following files is used by PAC for planning?
I. Shop order master
II
. Work center master
III
. Item master
IV. Routing
a
. I and II only
b
. I and III only
c
. II and III only
d
. II, III and IV
7
. Which of the following files will contain information on manufacturing lead time and lot
size?
a
. item master
b
. bill of material
c
. work center master
d
. shop order master
8
. The ____ shows the total standard time required to produce one end product in each work
center required for its manufacture:
a
. work center master
b
. routing
c
. bill of material
d
. item master
9
. Which file contains information on the efficiency and utilization of a work center?
a
. item master
b
. bill of material
c
. routing
d
. work center master
10
. A shop order for 1000 pieces is to be processed on work station 123. The setup time is 4
hours and the run time per piece is .08 hours. What is the required capacity on this work
center in standard hours?
a
.
4.08
b
.
0.08
c
.
80
d
.
84
e
.
4000
11
. All of the following are elements of manufacturing lead time EXCEPT:
a
. design time
b
. setup time
c
. run time
d
. wait time
e
. move time
72
12
. Which of the following statements is best?
a
. the largest element of manufacturing lead time is queue
b
. the larger the load, the longer the queue
c
. if queue is reduced, the lead time and work in process will be reduced
d
. all of the above are true
13
. A scheduling system in which the last operation on a routing is scheduled first and for
completion on the due date is called:
a
. forward scheduling
b
. backward scheduling
c
. infinite scheduling
d
. finite scheduling
14
. A scheduling system that assumes the required capacity will always be available is called:
a
. forward scheduling
b
. backward scheduling
c
. infinite scheduling
d
. finite scheduling
15
. Which of the following statements is best?
a
. implementation is achieved by issuing a shop order to manufacturing
b. engineering drawings, bills of material and routings may be included in a shop
packet
c
. the dispatch list is the instrument of priority control
d
. all of the above are true
16
. Which of the following are methods of reducing manufacturing lead time?
I. Subcontracting
II. Forward scheduling
III. Operation overlapping
IV. Operation splitting
a
. all of the above
b
. I and II
c
. II and III
d
. II and III
e
. III and IV
17
. Operation overlapping means:
a
. the same job running on two machines at the same time
b
. using alternate routings
c
. moving work to the next operation as a group of pieces is completed
d
. running two or more jobs at the same time
e
. locating work centers close together to reduce materials handling
18
. Which of the following statements is best?
a
. a bottleneck (capacity constraint resource) will control the throughput of all
products processed by it
b
. a time buffer should be established before a bottleneck
c
. work centers feeding a bottleneck should work at full capacity
73
d
. a and b are true
e
. b and c are true
19
. Which of the following statements is true?
I
. Throughput is the total volume of production passing through a facility.
II
. Throughput is controlled by the total capacity of a system.
III
. Work centers feeding bottlenecks should be 100% utilized.
a
. I only is true
b
. I and II only are true
c
. II and III only are true
d
. II only is true
e
. III only is true
20
. Which of the following statements is best?
a
. using a non-bottleneck 100% of the time produces 100% utilization
b
. time saved at a non-bottleneck saves nothing
c
. the capacity of a system depends on the capacity of the bottleneck
d
. a and b only are true
e
. b and c only are true
21
. Which of the following is NOT a principle of managing bottlenecks?
a
. a time buffer should be established after each bottleneck
b
. the rate of material fed to a bottleneck should be controlled
c
. do anything to increase the capacity of a bottleneck
d
. use alternate routings
e
. change the schedule
22
. If the previous backlog was 20 units, the planned input was 25 units and the planned output
was 30 units the planned backlog would be:
a
. 5 units
b
. 10 units
c
. 15 units
d
. 20 units
e
. 25 units
23
. The following information is to be used in this and the next question. For the last week a
work center had a planned input of 40 standard hours and an actual input of 36 standard
hours
. The planned output was 40, the actual output 42 standard hours and the beginning
backlog was 30 hours. The cumulative input variance was:
a
.
0
b
.
2
c
.
+2
d
.
4
e
.
+4
74
24
. The planned backlog was:
a
.
30
b
.
36
c
.
40
d
.
42
e
.
66
25
. Which of the following dispatching rules ignore due dates?
a
. first come, first served
b
. earliest operation due date
c
. shortest processing time
d
. a and b above both ignore due dates
e
. a and c above both ignore due dates
26
. Given the following information, which sequence will the orders be run in?
ORDER
CRITICAL RATIO
A 1.5
B 1.0
C 0.7
a
.
ABC
b.
BCA
c
.
ACB
d.
CBA
e
.
BAC
27
. If today is manufacturing day 100 and an order has a due date of 120 and a lead time
remaining of 25 days, the critical ratio would be:
a
.
0.8
b
.
1.2
c
.
1.25
d
.
0.25
e
.
0.2
28
. In a drum-buffer-rope scheduling system, the “drum” represents which of the following?
a
. a drum of jobs to be selected
b
. the master schedule for the operation
c
. a safety stock of material
d
. the constraint against too much being loaded into the master schedule
29
. Which of the following is concerned with very short-term detailed planning of the flow of
orders through manufacturing?
a
. sales and operations planning
b
. master production scheduling
c
.
MRP
d
. production activity control
75
30
. A scheduling system that assumes the required capacity will NOT always be available is
called:
a
. forward scheduling
b
. backward scheduling
c.. infinite scheduling
d.. finite scheduling
31
. An order for 100 of a product is processed on work center 123. The setup time is 60
minutes and the run time is 5 minutes per piece. If the order is run on two machines in the
work center, and the setups are made simultaneously, the elapsed time will be:
a
. 560 minutes
b
. 500 minutes
c
. 250 minutes
d
. 310 minutes
32
. The selection and sequencing of available jobs to be run at individual work stations and the
assignment of these jobs to workers is called:
a
. dispatching
b
.
scheduling
c
. priority management
d
. production control
33
. Given the following data, which job(s) will be late if the shortest process time sequencing
rule is used?
Today is day 100.
Job Process Due
Time Date
A 4 104
B 1 106
C 5 109
a
. all jobs will be on time
b
. A and B will be late
c
. A and C will be late
d
. B and C will be late
34
. Operation overlapping means:
a
. using alternate routings
b
. moving work to the next operation as a batch is completed
c
. running two or more jobs at the same time on the same machine
d
. locating work centers close together to reduce materials handling
35. Operation splitting means:
a
. the same job running on two jobs at the same time
b
. moving work to the next operation as a batch is completed
c
. running two or more jobs at the same time on the same machine
d
. locating work centers close together to reduce materials handling
76
Answers.