THE INTERNATIONAL UNIVERSITY (IU)
Department of Industrial System Engineering
Course IS017IU: Work Design & Ergonomics
FINAL EXAMINATION
Duration:
120 minutes
WORK DESIGN AND ERGONOMICS
Head of ISE Department
Lecturer:
Student ID:
Date:
May23, 2013
Assoc Prof. Ho Thanh Phong
Ho Trung Thao
Name:
INSTRUCTIONS:
1.
This is an open book examination.
2.
Calculator and dictionary are allowed. Student takes 2 decimal digits in calculation.
3.
Laptop, mobile phone, discussion and materials transfer are strictly prohibited.
4.
There are two parts in this exam. Students do Part I in the question paper, Part II in the answer
paper
Total pages:
06
(including this page)
PART I: MULTIPLE CHOICE QUESTIONS (20%):
There are 10 multiple-choice problems. Please circle the correct choice at each problem number. Each
problem is worth for 2 points with a total of 20 points.
1. Which of the following computational methods are used to calculate learning curve statistics?
a. Simple compounding
b. Exponential smoothing
c. Calculus
d. Logarithms
2. You have just timed a person doing a hair cut for the first time. It took 50 minutes. What is the learning rate (LR)
if the person took 35 minutes on the second hair cut?
a. 35 percent
b. 50 percent
c. 70 percent
d. 75 percent
3. If the Normal time for an operator is 2.4 minutes and the Observed time of Operator A is 2 minutes, the
performance rating of Operator A is:
a. 0.4
b. 4.4
c. 2.4
d. 1.2 (NT=OT x PR)
4. Work measurement techniques include all of the following except:
a. On the job training
b. Time study
c. Work sampling
d. Predetermined motion-time data systems
Work Design & Ergonomics – Midterm Exam
1
THE INTERNATIONAL UNIVERSITY (IU)
Department of Industrial System Engineering
Course IS017IU: Work Design & Ergonomics
5. Using the assembly-line balancing procedure, which of the following is the required cycle time if the production
time in minutes per day is 1440 and the required output per day in units is 2000?
a. 0.72
b. 1.388
c. 250
d. 500
6. You have just determined the actual number of workstations that will be used on an assembly line to be 8 using
the assembly-line balancing procedure. The cycle time of the line is 10 minutes and the sum of all that tasks
required on the line is 60 minutes. Which of the following is the correct value for the resulting line's efficiency?
a. 0.500
b. 0.650
c. 0.750
d. 0.850
7. Normal time is
a. the time after adjusting for allowances for personal needs, unavoidable delays, and fatigue.
b. the arithmetic mean of the times for each element measured, adjusted for unusual influence for each
element.
c. the time that workers never exceed when performing the task.
d. the observed time adjusted for pace
8. If the average observed time for an element is 2.00 minutes and the performance rating is 80%, what is the
normal time for this element?
a. 2.00 minutes
b. 2.50 minutes
c. 1.60 minutes
d. cannot be determined from the information given
9. An industrial engineer, watches a worker perform an assembly task. He notes that the worker completes 20 items
in exactly an hour. He rates the worker at 95% and recalls that the company's allowance factor is 10%. What is the
average observed time?
a. 20 items
b. 2.85 minutes
c. 3 minutes
d. 3.17 minutes
10. An MTM study is being performed on an unloading operation involving a wheelbarrow. The last task element is
missing, but the analyst knows that the time standard should be 18 seconds. If all of the times in the table are in
TMUs, what is the value of the missing element?
Element Description
Fill wheelbarrow
Deliver contents of
wheelbarrow
Return to pile
a.
b.
c.
d.
Element
AL3
Time
115
AN3
160
115 TMUs
225 TMUs
160 TMUs
135 TMUs
Work Design & Ergonomics – Midterm Exam
2
THE INTERNATIONAL UNIVERSITY (IU)
Department of Industrial System Engineering
Course IS017IU: Work Design & Ergonomics
PART II: WRITING (80%)
Question 1 (20 pts)
Develop the activity sequence model and determine the normal time for the following work activity: A
drill press operator reaches 20 cm (8 in) and pulls the feed lever down to engage the feed motion, which
takes 12 sec.
Solution:
Process time in TMU = 12(27.8) = 333.6 TMU
Activity sequence model = A1B0G1M1X33I0A0
Tn = 10(1 + 1 + 1 + 33) = 10(36) = 360 TMU (12.9 sec)
(5 pts)
(10 pts)
(5 pts)
Question 2 (20 pts)
The standard time is to be established for a manual work cycle by direct time study. The observed time for
the cycle averaged 4.80 min. The worker’s performance was rated at 90% on all cycles observed. After
eight cycles, the worker must exchange parts containers, which took 1.60 min, rated at 120%. The PFD
allowance for this class of work is 15%. Determine
(a) the normal time and (5 pts.)
(b) the standard time for the cycle. (5 pts.)
(c) If the worker produces 123 work units during an 8-hour shift, what is the worker’s efficiency? (10 pts.)
Solution:
(a) Normal time
Tn = 4.80(0.90) + 1.60(1.20)/8 = 4.32 + 0.24 = 4.56 min
(b) Standard time
Tstd = 4.56(1 + 0.15) = 5.244 min
(c) Standard hours Hstd = 123(5.244) = 645.0 min = 10.75 hr
Worker efficiency Ew = 10.75/8.0 = 1.344 = 134.4%
Question 3 (10 pts)
Determine the personal time, fatigue, and delay (PFD) allowance to be used for computing time standards in
the following situation. Second shift workers punch in at 3:30 p.m. and punch out at 12:00 midnight. They
are provided one-half hour for supper at 6:00 p.m., which is not counted as part of the 8-hour shift. For
purposes of determining the allowance, 30 minutes of break time (personal time and fatigue) are allowed
each worker. In addition, the plant allows 35 min for lost time due to unavoidable delays. What should the
PFD allowance factor be?
Solution: Allowance time for 30 min of break time plus 35 min for lost time = 65 min
Allowance factor Apfd = 480/(480-65) – 1 = 1.157 – 1 = 0.157 = 15.7%
Question 4 (30 pts)
The table below defines the precedence relationships and element times for a new assembled product.
(a) Construct the precedence diagram for this job. (5 pts.)
(b) If the ideal cycle time is 1.1 min and the repositioning time is 0.1 min, what is the theoretical
minimum number of workstations required to minimize the balance delay under the assumption that there
will be one worker per station? (10 pts.)
(c) Using largest candidate rule, assign work elements to stations. (10 pts.)
Work Design & Ergonomics – Midterm Exam
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THE INTERNATIONAL UNIVERSITY (IU)
Department of Industrial System Engineering
Course IS017IU: Work Design & Ergonomics
(d) Compute the balance delay for your solution. (5 pts.)
Work
element
1
2
3
4
5
Te (min)
0.5
0.3
0.8
0.2
0.1
Immediate
predecessors
1
1
2
2
Work
element
6
7
8
9
10
Te (min)
0.6
0.4
0.5
0.3
0.6
Immediate
predecessors
3
4,5
3,5
7,8
6,9
Solution:
(a) Precedence diagram.
(b) Twc = 0.5 + 0.3 + 0.8 + 0.2 + 0.1 + 0.6 + 0.4 + 0.5 + 0.3 + 0.6 = 4.3 min
w* = Min Int Twc/Tc = 4.3/1.1 = 3.9 rounded up to 4 workers and 4 workstations
(c) Largest candidate rule using Ts = 1.0 min
Element
3
6
10
1
8
7
2
9
4
5
Tc
0.8
0.6
0.6
0.5
0.5
0.4
0.3
0.3
0.2
0.1
Predecessor
1
3
6, 9
3, 5
4, 5
1
7, 8
2
2
Station
1
2
3
4
5
Element
1
2
4
3
5
6
7
8
9
10
Te
0.5
0.3
0.2
0.8
0.1
0.6
0.4
0.5
0.3
0.6
Te
1.0
0.9
1.0
0.8
0.6
4.3
(d) Balance delay d = (5(1.0) – 4.3)/5(1.0) = 0.14 = 14%
GOOD LUCK
Work Design & Ergonomics – Midterm Exam
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