Practice problems Exam I
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University of New Mexico, Main Campus *
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Course
300
Subject
Industrial Engineering
Date
Dec 6, 2023
Type
Pages
5
Uploaded by MinisterWater11566
1
Practice examples - Exam I
1.
Place the following items in the correct location on the Product Process Matrix below:
a)
Coca-Cola Bottling
b)
S
cholar’s Inn Bakehouse Bread
c)
J. Lo’s Wedding Dress(es)
d)
Oil Refinery
Low volume
Low volume
Higher volume
High volume
Low standardization
High standardization
One of a kind
Many products
Few products
Commodity products
Job shop
Batch
Assembly line
or flow shop
Continuous
Flow
2.
On the graph below, circle the companies that are in the operations frontier, identify the
“world class”
companies, and put a box around those companies that are dominated.
Low price
Responsiveness
3.
Using the graph below, detailing an assembly line with two work stations, answer the following
questions
1
2
3
4
5
1
2
3
4
5
6
6
1.5 min
1.5 min
1.5 min
1.5 min
1.5 min
1.5 min
2 min
2 min
2 min
2 min
2 min
2 min
Station 1
Station 2
Job 1
Job 1
Job 2
Job 2
a)
What is happening to Station 1 that is causing the gaps in production? is it blocking or starving?
b)
What is the bottleneck?
c)
What is the system cycle time?
d)
Is there an inventory location between station 1 and station 2? Why?
4.
The new computer controlled NCX machine has replaced 3 older machines. Before the replacement,
each part required two minutes of processing on the first machine, then eight minutes of processing on the
2
second machine, and finally four minutes on the third. (Each of these machines had a dedicated operator.)
The new NCX-10 machine can do all 3 steps in 10 minutes per part. As a result of the introduction of the
NCX-10:
a)
flow time for this process has:
(i)
increased
(ii)
decreased
(iii)
not changed
b)
capacity rate for this process has:
(i)
increased
(ii)
decreased
(iii)
not changed
5.
In any given week
, a few members of the writing staff work on a draft of a new script for “The
Simpsons”. The
second stage is a rigorous rewriting process. In the third stage, the script is read aloud by
the cast, and taped. The final stage, animation, is done by hand. Each of the ''Simpsons'' episodes takes nine
months to complete. ''The Simpsons'' is in production year round and there is no variability in the process.
Twenty new episodes are made and released each year.
a)
At any given t
ime, how many “Simpsons” episodes ar
e in production?
(Determine first the throughput
rate of the process that creates new “Simpsons” epi
sodes and the flow time of each episode.)
6.
Panchero’s restaurant
has two items on their menu: Fajitas and Quesadillas. The serving process is as
following: customers form two lines to order the food (ORDER), wait for the food to be packaged
(PACKAGE), make payment (PAY), and fill their drinks and take fork and napkins (FILL). Since
customers do not have choice of meat and vegetable when they order Quesadillas, the PACKAGE stage for
Quesadillas is shorter than for Fajitas.
The restaurant serves dinner from 6 pm to 9 pm. From 6 pm to 8 pm, 60 customers per hour order Fajitas
and 40 customers per hour order Quesadillas. From 8pm to 9 pm, 40 order Fajitas and 30 order Quesadillas.
The processing rates are specified in the process flow diagram:
a)
Calculate the utilization of each stage during peak time (6-8pm). Where is the bottleneck?
b)
Draw an inventory buildup diagram. At what time would the last customer leave the system?
7.
Consider the following six tasks that must be assigned to 4 workers on an assembly line. Each worker
must perform at least one task.
Time to complete task
Task 1:
30 seconds
Task 2:
25 seconds
Task 3:
35 seconds
Task 4:
40 seconds
Task 5:
15 seconds
Task 6:
30 seconds
The current assembly line configuration assigns the workers in the following way:
3
Worker 1:
Task 1
Worker 2:
Task 2
Worker 3:
Task 3, 4
Worker 4:
Task 5, 6
a)
What is the capacity of the current line?
b)
Now reallocate these tasks to the same four workers to increase the capacity of the whole line, subject
to the conditions that (1) a worker can only perform two adjacent operations and (2) all tasks need to
be done in their numerical order. What is the capacity of this line now?
For questions 8-9: Reference the Apple Juice Case on a peak day
8. W
hen would the truck drivers start waiting if we buy only one bin (320 tons)?
9.
For the Apple Juice Case, now assume that the plant
begins work at 11am
instead of 7am. In this
scenario, the trucks still arrive at 7am and are permitted to unload at the conveyor belts. The conveyor belts
can also unload the apples into the bins, but the rest of the plant doesn't start processing apples until
11am. At what time do the bins fill and trucks begin to wait?
10.
The McLhenny Company produces Tabasco Sauce from peppers only harvested on Avery Island in LA.
The bulk of the process flow of the production process is in storing the sauce in wood barrels for 2 years.
The plant ships 1000 barrels of sauce per week. How much work in process inventory is stored in barrels?
11.
Consider the following manufacturing process flow diagram. All taks (A, B, and C) are necessary to
create each finished unit. Cycle times, in minutes/unit, and the required resources are shown at each task.
a)
Which is the bottleneck?
-
Task A
-
Task B
-
Worker 1
-
Worker 2
b)
What is the cycle time of the system?
-
2 minutes
-
3 minutes
-
5 minutes
-
10 minutes
-
13 minutes
-
15 minutes
c)
What is the flow time?
-
2 minutes
-
3 minutes
-
5 minutes
-
10 minutes
-
13 minutes
-
15 minutes
d)
What is the capacity of the system?
-
30 units/hour
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4
-
20 units/hour
-
12 units/hour
-
6 units/hour
-
4.6 units/hour
-
4 units/hour
e)
What is the capacity of the system if we hire an additional Worker 2 who can process a unit (on Task
C) in 10min?
-
10 units/hour
-
12 units/hour
-
20 units/hour
-
6 units/hour
-
4.6 units/hour
-
4 units/hour
12.
A manufacturing shop is designed to operate most efficiently at an output of 550 units per day.
In the
past month the plant produced 490 units.
What was their capacity utilization rate last month?
13.
Consider a fish processing company with a freezer as a storage space. We want to analyze the inventory
of the freezer over time. The input (i.e., demand=
(t)) and processing rates (i.e., capacity =
(t)) given by
the diagrams below.
a)
Draw an inventory buildup diagram when there is infinite freezer capacity:
b)
Challenge: What is the average throughput (tons/month)?
c)
What is the average monthly inventory (tons)?
d)
How does the buildup diagram change when your freezer has a capacity of only 10,000 tons? Draw a
new buildup diagram!
14.
Consider the two-step service process shown in the diagram below. Assume that the system is in steady
state and that the average number of customers waiting prior to each process steps and the average number
of customers in each process step are given as shown in the diagram.
a)
How many customers (total inventory) are in the system?
b)
Which step is the bottleneck?
c)
What is the capacity of the system?
5
d)
What is the flow time of the system?
e)
What will be the utilization of service rep at Step 1?
f)
What is the average wait in sub-system 1?
15.
Consider the following Project
Task
Predecessor
Expected
Time
A
–
8.00
B
A
10.33
C
A
8.67
D
B
12.00
E
B, C
13.67
F
C
8.67
G
D, E
13.67
H
E, F
10.33
I
G, H
4.33
a)
Draw the Project network and estimate the EST, EFT, LST, LFT and the slack for each task.
b)
What is the critical path for this project?