978-0470444047 Chapter 2 Part 1

Chapter 2

Product, Process, and Schedule

Design

Answers to Problems at the End of Chapter 2 2-1

SECTION 2.1

2.1 Identify the hospital functions and departments to be incorporated in the facilities plan.

Identify the key entities for which flow requirements will be needed, e.g., people,

2.2 It is important for the various design decisions to be integrated so that all critical issues

have been considered before product and process designs are finalized. Using a linear or

series approach can result in multiple re-starts of the design process because of “down–

2.3 Research question. Depending on the comprehensiveness of the collection of periodicals

SECTION 2.2

2.4 – 2.6 Research question. Depending on the comprehensiveness of the collection of

2.7 Research question. The Internet will likely be the best source of information needed to

SECTION 2.3

2.8 The assigned chart submitted for a cheeseburger will vary depending on the assumptions

2.9 The assembly chart shows only the operations and inspections associated with the

materials.

2.10 – 2.11 The solution depends on the recipe chosen.

SECTION 2.4

2.13 Given System: (all Ik values are rounded to the nearest integer)

The scrap values and scrap cost at each step are as follows:

System w/Reversed Scrap Rates:

The scrap values and scrap cost at each step are as follows:

Due to the lower scrap cost the system with reversed scrap rates would be preferred,

which is consistent with the claim made in Section 2.4.2.

2.14 For simplicity the rework operations are indicated by Rk. All Ik values are rounded to the

nearest integer.

Given system: Following the derivation method given in Section 2.4.2.2, we have the

expression for I1:

Answers to Problems at the End of Chapter 2 2-3

System w/Reversed Scrap Rates: Using the same derivation, we have the following:

Based solely on the total rework costs of the two systems, the system with reversed scrap

rates is preferred, which is consistent with the result of Problem 2.13. You should note,

however, that the system with reversed scrap rates requires more input to the system to

meet the demand.

2.15 All Ik values are rounded to the nearest integer.

2.16 We solve this problem working in reverse.

Solving for I1 and substituting in the appropriate parameters, we have the following:

2.17 All Ik values rounded to the nearest integer. For machines 1, 2, and 3:

Machine 4 operates for half of the amount of time as machines 1, 2, and 3.

We know that Ik = Qk. So,

Running the rework operation on the same shift as the remainder of the cell would cause

the machine fraction to reduce to 0.68, or 1 machine. This may allow for the addition of

the rework machine to the cell.

2.18 All Ik values rounded to nearest integer. Let A1 denote the first step in the production

process, and A2 denote the last step.

Similarly,

Answers to Problems at the End of Chapter 2 2-5

We know that Ik = Qk. So,

2.19 All Ik values are rounded to the nearest integer.

Setup times are identical for machines A, B, and C for a particular product. The setup

time for product X, regardless of the machine, is 20 mins; the setup time for product Y is

40 mins., regardless of the machine. A critical piece of information needed to determine

the number of machines required is the length of production runs between setups. If a

single setup is needed to produce the annual requirement of a product on a machine, then

the number of machines required is determined as follows:

Answers to Problems at the End of Chapter 2 2-6

If setups occur more frequently, then additional machines might be required due to the

lost production time consumed by setups.

2.20 All Ik values are rounded to the nearest integer.

2.21 Using the equations to solve Problem 2.20, we simply change the input values. Let

represent the new scrap percentage. For this solution, we are assuming the 5% reduction

The opinion response will depend on the student. However, the response should look

something like the following.

2.22 The value of H is up to the student or instructor. Any value will provide sufficient

illustration for the follow-up opinion question. For the purposes of this solution, we will

assume H is a variable value and solve symbolically.

Answers to Problems at the End of Chapter 2 2-7

It should be apparent that by reducing the scrap percentage will reduce the number of

machines necessary. Assuming one 8 hour shift per day, 5 days per week, reducing the

2.23

2.24 Let CA, CB, B, F, FA, IN, and M represent component A, component B, blanking,

2.26 Let BC, BY, CB, DA, IN, KP, and TC represent the bottom cover, battery cover, circuit

board, disassembly, inspection, keypad, and top cover, respectively. In addition, let Mxx

represent molding operations for specific components; Pxx represent painting operations

for specific components; and INx represent inspection stations in order of occurrence.

All Ik values are rounded to the nearest integer.

Answers to Problems at the End of Chapter 2 2-8

2.27 Shown below is the probability mass function for number of good castings produced (x),

based on Q castings scheduled for production.

Answers to Problems at the End of Chapter 2 2-9

2.28 Shown below is the probability mass function for number of good castings produced (x),

based on Q castings scheduled for production.

Answers to Problems at the End of Chapter 2 2-10

Shown below is the matrix of net income for each combination of Q and x.

Answers to Problems at the End of Chapter 2 2-11

2.29 Shown below is the probability mass function for number of good castings produced (x),

based on Q castings scheduled for production.

2.30a Shown below is the probability mass function for the number of good custom-designed

castings produced (x), based on Q castings scheduled for production.

Answers to Problems at the End of Chapter 2 2-13

For a given value of Q, multiplying the net income in the column by the probability of its

occurrence and summing over all values of x yields the following expected profits for

each value of Q. As shown, the optimum number to schedule is 5, with an expected net

profit of $35,335.

2.30b The probability of losing money on the transaction is the probability of the net income

2.30c Using Excel it is easy to perform the sensitivity analysis. By varying the cost parameter,

2.31 Shown below is the probability mass function for number of good high precision formed

Answers to Problems at the End of Chapter 2 2-14

Shown below is the matrix of net income for batch sizes of 10, 11, and 12. Also shown

below is the expected profit based on batch sizes of 10, 11, and 12, as well as the

probability of losing money. A batch size of 12 yields the smallest expected profit. Based

on the probability of losing money, the least attractive alternative is a batch size of 10.

2.32 Shown below is the probability mass function for the number of good wafers (x) resulting

from a production batch size of Q.

Shown below is the matrix of net profit resulting from combinations of Q and x.

Shown below are the expected profits and probabilities of losing money for various batch

sizes. The optimum batch size is 7, with a 0.0129 probability of losing money.

2.33 Shown below is the probability mass function for the number of good die castings (x) in a

production batch of size Q.

Shown below is the matrix of net profits resulting from various combinations of Q and x.

Shown below are the expected profits and probabilities of losing money for various

values of Q, the batch size. From the results obtained, the optimum batch size is 28. The

probability of losing money, which is the probability of less than 25 die cast parts being

acceptable, equals 0.0022.