Select Page
```Some tasks and the order in which they must be performed according to their assembly
requirements are shown in the following table. These are to be combined into workstations
to create an assembly line. The assembly line operates 71?2 hours per day. The output
requirement is 1,000 units per day.
Preceding Time Preceding Time
A - 15 G C 11
B A 24 H D 9
C A 6 I E 14
D B 12 J F,G 7
E B 18 K H,I 15
F C 7 L J,K 10
a. What is the workstation cycle time required to produce 1,000 units per day?
b. Balance the line using the longest task time based on the 1,000-unit forecast, stating
which tasks would be done in each workstation.
c. For (b), what is the efficiency of your line balance, assuming it is running at the cycle
time from part (a)?
d. After production was started, Marketing realized that it understated demand and must
increase output to 1,100 units. What action would you take? Be specific and quantitative

8. An initial solution has been given to the following workcenter layout problem. Given
the fl ows described and a cost of \$2.00 per unit per foot, compute the total cost for the
layout. Each location is 100 feet long and 50 feet wide as shown in the following fi gure.
Use the centers of departments for distances and measure distance using metropolitan-rectilinear
distance.
Department
A B C D
A 0 10 25 55
Department B 0 10 5
C 0 15
D 0

100' 100' 100'
50' A B C 50'
D 50'

CHAPTER 12

7. The following table lists all costs of quality incurred by
Sam's Surf Shop last year. What
was Sam's appraisal cost for quality last year?
Annual inspection costs \$ 155,000
Annual cost of scrap materials 286,000
Annual rework cost 34,679
Annual cost of quality training 456,000
Annual warranty cost 1,546,000
Annual testing cost 543,000

10. A manufacturing company has been inspecting units of output from a
process. Each product
inspected is evaluated on fi ve criteria. If the unit does not meet
standards for the criteria
it counts as a defect for the unit. Each unit could have as few as zero
defects, and as
many as fi ve. After inspecting 2,000 units, they discovered 33 defects.
What is the DPMO
measure for this process?

CHAPTER 13

6. C-Spec, Inc., is attempting to determine whether an existing machine is
capable of milling
an engine part that has a key specification of 4+6 .003 inches.
After a trial run on this machine, C-Spec has determined that the machine
has a sample
mean of 4.001 inches with a standard deviation of .002 inch.

a. Calculate the Cpk for this machine.

b. Should C-Spec use this machine to produce this part? Why?

7. Ten samples of 15 parts each were taken from an ongoing process to
establish a p-chart
for control. The samples and the number of defectives in each are shown in
the following
table:

Number of Number of
Defective Items Defective Items
Sample n in the Sample Sample n in the Sample

1 15 3 6 15 2
2 15 1 7 15 0
3 15 0 8 15 3
4 15 0 9 15 1
5 15 0 10 15 0

a. Develop a p-chart for 95 percent confi dence (1.96 standard deviation).
b. Based on the plotted data points, what comments can you make?

8. A shirt manufacturer buys cloth by the 100-yard roll from a supplier.
For setting up a
control chart to manage the irregularities (e.g., loose threads and tears),
the following data
were collected from a sample provided by the supplier.

Sample 1 2 3 4 5 6 7 8 9 1 0

Irregularities 3 5 2 6 5 4 6 3 4 5

a. Using these data, set up a c-chart with z 5 2.
b. Suppose the next five rolls from the supplier had three, two, five,
three, and seven irregularities.
Is the supplier process under control?

9. Resistors for electronic circuits are manufactured on a high-speed
automated machine.
The machine is set up to produce a large run of resistors of 1,000 ohms
each.
To set up the machine and to create a control chart to be used throughout
the run,
15 samples were taken with four resistors in each sample. The complete list
of samples
and their measured values are as follows:

1                              1010    991     985     986
2                              995      996     1009   994
3                              990      1003   1015   1008
4                              1015    1020   1009    998
5                              1013    1019   1005    993
6                              994      1001   994     1005
7                              989      992     982     1020
8                              1001    986     996     996
9                              1006    989     1005   1007
10                            992      1007   1006   979
11                            996      1006   997     989
12                            1019     996    991     1011
13                            981       991    989     1003
14                            999       993    988     984
15                            1013     1002  1005    992

Develop an X-chart and an R-chart and plot the values. From the charts,
can you make about the process? (Use three-sigma control limits as in
Exhibit 13.7.)

Your company assembles five different models of a motor scooter that is sold in specialty stores in the United States. The company uses the same engine for all five models. You have been given the assignment of choosing a supplier for these engines for the coming year. Due to the size of your warehouse and other administrative restrictions, you must order the engines in lot sizes of 1,500 each. Because of the unique characteristics of the engine, special tooling is needed during the manufacturing process which you agree to reimburse the supplier. Your assistant has obtained quotes from two reliable engine suppliers and you need to decide which to use. The following data has been collected:

Requirements (annual forecast)	18,000 units
Weight per engine	25 pounds
Order processing cost	\$120 per order
Inventory carry cost	25 percent of the average value of inventory per year

Note:Assume that half of lot size is in inventory on average (1,500/2 = 750 units).
Two qualified suppliers have submitted the following quotations:
Unit Price	Supplier 1	Supplier 2
1 to 1,499 units/order	\$510.00	\$505.00
1,500 to 2,999 units/order	500.00	505.00
3,000 + units/order	490.00	488.00
Tooling costs	\$22,000	20,000
Distance	1125 miles	100 miles

Note:Per ton-mile = 2,000 lbs. per mile

A. Perform a total cost of ownership analysis and select a supplier.

B.  Would it make economic sense to order in truckload quantities?  Would your supplier selection change if you ordered truckload quantities?

Jill’s Job Shop buys two parts (Tegdiws and Widgets) for use in its production system from
two different suppliers. The parts are needed throughout the entire 52-week year. Tegdiws are
used at a relatively constant rate and are ordered whenever the remaining quantity drops to the
reorder level. Widgets are ordered from a supplier who stops by every three weeks. Data for
both products are as follows:
ITEM
Annual demand
Holding cost (% of item cost)
Setup or order cost
Safety stock
Item cost

TEGDIW WIDGET
\$10,000
\$5,000
20%
20%
\$150.00
\$25.00
4 weeks
1 week
55 units
5 units
\$10.00
\$2.00

a. What is the inventory control system for Tegdiws? That is, what is the reorder quantity and
what is the reorder point?

Item X is a standard item stocked in a company’s inventory of component parts. Each year the
firm, on a random basis, uses about 2,000 of item X, which costs \$25 each. Storage costs, which
include insurance and cost of capital, amount to \$5 per unit of average inventory. Every time an
order is placed for more item X, it costs \$10.
a. Whenever item X is ordered, what should the order size be?
b. What is the annual cost for ordering item X?
c. What is the annual cost for storing item X?

In the past, Taylor Industries has used a fixed-time period inventory system that involved taking a complete inventory count of all items each month. However, increasing labor costs are forcing Taylor Industries to examine alternative ways to reduce the amount of labor involved in inventory stockrooms, yet without increasing other costs, such as shortage costs. Here is a random sample of 20 of Taylor’s items.

Item Annual Item Annual

Number Usage Number Usage

__________________________________________________________

1 \$1,500 11 \$13,000

2 12,000 12 600

3 2,200 13 42,000

4 50,000 14 9,000

5 9,600 15 1,200

6 750 16 10,200

7 2,000 17 4,000

8 11,000 18 61,000

9 800 19 3,500

10 15,000 20 2,900

a. What would you recommend Taylor do to cut back its labor cost? (Illustrate using an ABC plan.)

b. Item 15 is critical to continued operations. How would you recommend it be classified?

```