Deck 7: Design for Quality and Product Excellence

Question 1

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Newfonia, Inc. is working on a design for a new smart phone. Marketing staff conducted extensive surveys and focus groups with potential customers to determine the characteristics that the customers want and expect in a smart phone. Newfonia's studies have identified the most important customer expectations as
• Initial cost
• Reliability
• Ease of use
• Features
• Operating cost
• Compactness
Develop a set of technical requirements to incorporate into the design of a House of Quality relationship matrix to assess how well your requirements address these expectations. Refine your design as necessary, based upon the initial assessment.

Answer 1

Given that the customer responses regarding what they want and expect in a smart phone are as follows as per priority.
The parameters which have a high priority also have a higher weightage as shown in the table.The designer observes from the analysis of customer responses for a new smartphone the following
• The customer wants a low initial cost phone which is also reliable (high quality) and has ease of use.• The customer wants lots of features but he is also interested in ease of use and compactness.
• He wants low operating cost but all the features and long battery life.The designer needs to prioritize these conflicting desires and wants of the customer. There are interrelationships between the various aspects of the phone also. The house of quality shown below tries to maximize the customer desires.
The designer now has the following order of priorities for designing the mobile phone:
• Operating system
• Number of components
• Battery
• Material of construction
• Dimensions
• Weight

Question 2

Explain the concept and the principal benefits of QFD.

Answer 2

The Quality Function Deployment (QFD) refers to both (i) deciding on what will satisfy the customers and (ii) transforming those desires into the requisite designs. The QFD concept ensures that there is good communication between marketing and design, between design and manufacturing, and between purchasing and suppliers.
Some of the benefits of QFD are as follows:
• The QFD concept helps in pinpointing how each of the functional areas such as manufacturing, marketing, purchasing and design can contribute to the satisfaction of the needs or wants of the consumers.
• QFD can help in diagnosing the causes of customer dissatisfaction.
• QFD can also help in analyzing the strengths and weaknesses of competitors.
• QFD reduces design time as well as the product development time, improves productivity and enhances quality.
• QFD allows simulation of the impact of a new product design on the company.

Question 3

Explain the product life characteristics curve and its implications for reliability and quality control.

Answer 3

A number of products especially for the electronics industry show a very high rate of failure initially, which is followed by a constant failure rate (which occurs randomly) and again the failure rate increases steeply as the product approaches its design life. The product life characteristic curve is a graph which has on the Y - axis, the failure rate and on the X - axis time duration as shown below for a product which has a designed life of 4 hours. This graph has the shape of a bath tub which shows three distinct periods on the X axis.
Some of these initial high failure rates cannot be avoided by the normal quality control processes. Product manufacturers to prevent such products entering the market and thereby earning the wrath of consumers may want to initially test the products in the factory for a stipulated number of hours, so that products which fail initially can be weeded out, before releasing to the market. Similarly, the warranty terms for the product can be suitably worded once they know the nature of the product life characteristic curve
Therefore, the product life characteristic curve is an important concept for product manufacturers.

Question 4

Discuss environmental responsibility issues relating to product design facing businesses today.

Question 5

(This exercise would best be performed in a group.) Suppose that you were developing a small pizza restaurant with a dining area and local delivery. Develop a list of customer requirements and technical requirements and try to complete a House of Quality. What service standards might such an operation have?

Question 6

A specification for the length of an auto part at PartsDimensions, Inc. is 5.0 ± 0.10 centimeters (cm). It costs $40 to scrap a part that is outside the specifications. Determine the Taguchi loss function for this situation.

Question 7

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Two processes, P and Q, are used by a supplier to produce the same component, Z, which is a critical part in the engine of the BearingPort 778 airplane. The specification for Z calls for a dimension of 0.24 mm ± 0.03. The probabilities of achieving the dimensions for each process based on their inherent variability are shown in the table found in the worksheet tab Prob. 7-16 in the Excel file C07Data. If k = 60,000, what is the expected loss for each process? Which would be the best process to use, based on minimizing the expected loss?

Question 8

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
A manufacturer of MP3 players purchases major electronic components as modules. The reliabilities of components differ by supplier (see the system diagram below). Suppose that the configuration of the major components is given by:

The components can be purchased from three different suppliers. The reliabilities of the components are as follows:

Transportation and purchasing considerations require that only one supplier be chosen. Which one should be selected if the player is to have the highest possible reliability?

Question 9

Discuss the importance of and impediments to reducing the time for product development.

Question 10

Outline the process of building the House of Quality. What departments and functions within the company should be involved in each step of the process?

Question 11

What is a reliability function? Explain how to determine it.

Question 12

Describe the basic approach to design for excellence.

Question 13

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Newfonia, Inc. (Problem 2) faces three major competitors in this market: Oldphonia, Simphonia, and Colliefonia. It found that potential consumers placed the highest importance on reliability (measured by such things as freedom from operating system crashes and battery life), followed by compactness (weight/bulkiness), followed by flexibility (features, ease of use, and types of program modules available). The operating cost was only occasionally noted as an important attribute in the surveys. Studies of their products yielded the information shown in the table in the worksheet tab Prob.7-3 in the Excel file C07Data. Results of the consumer panel ratings for these competitors are also shown in that spreadsheet. Using this information, modify and extend your House of Quality from Problem 2 and develop a deployment plan for the new smartphone. On what attributes should the company focus its marketing efforts?

Question 14

A team was formed to study the auto part at Parts- Dimensions described in Problem 8. While continuing to work to find the root cause of scrap, the team found a way to reduce the scrap cost to $20 per part.
a. Determine the Taguchi loss function for this situation.
b. If the process deviation from target can be reduced to 0.040 cm, what is the Taguchi loss?

Question 15

The average time to handle a call in the Call- Nowait call processing center has a specification of 6 ± 1.25 minutes. The loss due to a mishandled call is $12. A sample of 25 calls was drawn from the process and the results, in minutes, can be found in the C07Data file for Prob. 7-17.
a. Compute the value of k in the Taguchi loss function.
b. What is the expected loss from this process based on the sample data?

Question 16

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
An electronic missile guidance system at Mguide, Inc. consists of Components A, B, C, and D, which have reliabilities of 0.98, 0.97, 0.91, and 0.99, respectively (see the following diagram).

a. What is the reliability of the entire system?
b. Suppose the customer requires a reliability of at least 0.98. Try to find a configuration that meets this requirement using the minimum number of components.

Question 17

Most children (and many adults) like to assemble and fly balsa-wood gliders. From your own experiences or from interviews with other students, define a set of customer requirements for a good glider. (Even better, buy one and test it to determine these requirements yourself.) If you were to design and manufacture such a product, how would you define a set of technical requirements for the design? Using your results, construct a relationship matrix for a House of Quality.

Question 18

Explain and give an example of nominal specifications and tolerances in both manufacturing and service.

Question 19

Explain how to compute the reliability of series, parallel, and series-parallel systems.

Question 20

Explain the purpose of design reviews and how they facilitate product development.

Question 21

What is concurrent engineering? What benefits does it have?

Question 22

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Ruido Unlimited makes electronic soundboards for car stereos. Output voltage to a certain component on the board must be 12 ± 0.5 volts. Exceeding the limits results in an estimated loss of $60. Determine the Taguchi loss function.

Question 23

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Massive Corporation's tested five motors in a 900-hour test. Compute the failure rate if, three failed after 200, 475, and 750 hours and the other two ran for the full 900 hours each.

Question 24

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Bestronics has a three-step process for processing customer sales. First, the cashier must look up the customer's loyalty card on the company's information system. Second, the cashier enters the transaction on the point-of-sale register. Third, the cashier processes the credit card through a verification system.
a. If the reliability of the information system is 0.998, the reliability of the point-of-sale register is 0.992 and the reliability of the credit card verification system is 0.978, what is the overall system reliability?
b. If the store manager wants to ensure at least a 98 percent system reliability, make a recommendation of how to do this.

Question 25

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Georgio's Giant Gyros conducted consumer surveys and focus groups concerning a new gyro sandwich design and the restaurant facility, and identified the most important customer expectations (not in any order of priority) as:
• Tasty, attractive, moderately healthy food
• Speedy service
• An easy-to-read menu board
• Accurate order filling
• Perceived value
Develop only a set of technical requirements to incorporate into the design of the product and its delivery. Use a House of Quality relationship matrix to assess how well your requirements address these expectations. Include some technical dimensions that may be used to measure tasty, attractive, and "healthy" food; speedy service, acceptable menu boards, order accuracy, or perceived value. Refine your design as necessary based upon the initial assessment.

Question 26

Explain the Taguchi loss function and how it is used in process and tolerance design.

Question 27

What is robust design? Explain why it is important for both consumers and manufacturers.

Question 28

Describe different forms of product testing.

Question 29

Fill in the following relationship matrix of a House of Quality for a screwdriver. By sampling your classmates, develop priorities for the customer attributes and use these and the relationships to identify key technical requirements to deploy.

Question 30

An electronic component at Eltcomp has a specification of 100 ± 0.4 ohms. Scrapping the component results in a $81 loss.
a. What is the value of k in the Taguchi loss function?
b. If the process is centered on the target specification with a standard deviation of 0.2 ohm, what is the expected loss per unit?

Question 31

The life of a Supercellular phone battery is normally distributed with a mean of 950 days and standard deviation of 40 days. Using the Excel functions (see Chapter 6), determine the following:
a. What fraction of batteries is expected to survive beyond 1010 days?
b. What fraction will survive fewer than 900 days?
c. Draw a chart of the reliability function using Excel.
d. What length of warranty is needed so that no more than 10 percent of the batteries will be expected to fail during the warranty period?

Question 32

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Magnaplex, Inc. has a complex manufacturing process, with three operations that are performed in series. Because of the nature of the process, machines frequently fall out of adjustment and must be repaired. To keep the system going, two identical machines are used at each stage; thus, if one fails, the other can be used while the first is repaired (see accompanying figure).
Production System

The reliabilities of the machines are as follows:

a. Analyze the system reliability, assuming only one machine at each stage (all the backup machines are out of operation).
b. How much is the reliability improved by having two machines at each stage?

Question 33

What is Design for Six Sigma (DFSS)? Explain the four basic elements of DFSS and the various tools and methodologies that comprise this body of knowledge.

Question 34

Define reliability. Explain the definition thoroughly.

Question 35

What is design failure mode and effects analysis (DFMEA)? Provide a simple example illustrating the concept.

Question 36

An automated production system at Autoprod, Inc. consists of three operations: turning, milling, and grinding. Individual parts are transferred from one operation to the next by a robot. Hence, if one machine or the robot fails, the process stops.
a. If the reliabilities of the robot, turning center, milling machine, and grinder are 0.994, 0.980, 0.95, and 0.88, respectively, what is the reliability of the system?
b. Suppose that two grinders are available so that the system does not stop if one fails. What is the reliability of the system?

Question 37

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Georgio's Giant Gyros (Problem 4) acquired some additional information about product characteristics. It found that consumers placed the highest importance on taste appeal (especially flavor), followed by healthiness (measured by sodium content and calories), value, and service. The menu board and accurate order filling appeared to be less important attributes in the surveys. Georgio faces three major competitors in this market: Mario's, Gyroking, and Antonio's. Studies of their products yielded the information shown in the worksheet tab Prob.7-5 in the Excel file C07Data. Results of the consumer panel ratings for each of these competitors can also be found there (a 1-5 scale, with 5 being the best). Using this information, modify and extend your House of Quality from Problem 4 and develop a deployment plan for a new gyro. Assume that a separate study will be made on the physical facilities and design of service delivery. On what product attributes should the company focus its marketing efforts?

Question 38

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
An automatic cookie machine at ACM, Inc. must deposit a specified amount of 25 ± 0.3 grams (g) of dough for each cookie on a conveyor belt. It costs $0.03 to scrap a defective cookie. A sample of 50 cookies was drawn from the production process, which has been determined to be approximately normally distributed, and the results, in grams, can be found in worksheet tab Prob. 7-12 in the Excel file C07Data.
a. What is the value of k in the Taguchi loss function?
b. Determine how much the process varies from the target specification, based on the mean difference and standard deviation of the sample results. What is the expected loss per unit?

Question 39

Widetred, Inc. makes automobile tires that have a mean life of 60,000 miles with a standard deviation of 2,000 miles. Using Excel functions (see Chapter 6), determine the following:
a. What fraction of tires is expected to survive beyond 63,250 miles?
b. What fraction will survive fewer than 56,600 miles?
c. Draw a chart of the reliability function using Excel.
d. What length of warranty is needed so that no more than 5 percent of the tires will be expected to fail during the warranty period?

Question 40

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
CajaGigante, a large department store, has a very successful and profitable package-wrapping department. The department uses two complex bow-making machines that work inline to make the bows for the packages. There is one skilled operator who knows how to operate the machines. She had been very reliable, but recently has had increasing health problems which caused her to miss work about 10 percent of the time. Bow-making Machine 1 has a reliability of 0.97. Machine 2 has a reliability of 0.90.
a. What is the current reliability of the system, including the operator?
b. Management is considering either scrapping Machine 2 and replacing it with a new machine which has a reliability of 0.97 at a cost of $5,000, or training another operator to fill in when the first operator is absent at a cost of $5,100. The prospective trainee has an excellent attendance record and has only been absent 4 days out of 250 work days for the department, last year. Management estimates that profits from the department would increase by $6,000 per year, if the bow-making line operated at 100 percent of capacity. If management wants to pay off its investment in the first year, determine the expected net profit for each alternative, and recommend which one will be the most profitable to management.

Question 41

Prepare a full DFMEA for a casual dining restaurant. Consider failure modes that might occur both in food preparation and in service. Clearly explain and justify your choices for the severity, likelihood, and detection ratings.

Question 42

What is the difference between a functional failure and a reliability failure?

Question 43

What is fault tree analysis? How does it differ from DFMEA?

Question 44

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
National Partamiento installs and maintains thousands of refrigerators and other appliances in rental apartments across the country. They have conducted a short study of failure rates based on following the performance of 25,440 refrigerators that were installed during one month a year ago. The table found in the worksheet tab Prob.7-30 in the Excel file C07Data on the Student Companion Site contains the data. The data show the number of failures of these 25,440 refrigerators each month over the past year.
a. Compute the average failure rate, ?. Is the failure rate relatively constant each month?
b. Use regression analysis to predict future failures. What is the predicted number of failures each month for the next two years (that is, through month 36)?
c. If the refrigerators are typically under a 36-month warranty, how many cumulative failures would be predicted in 36 months? What percentage of the total does this represent?
d. What are the strengths and limitations of using regression analysis in this situation?

Question 45

Explain concept development and innovation. Describe the importance of innovation and creativity in concept development.

Question 46

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
A computer chip designed by the MicroKeeb Co. has a specification for the distance between two adjacent pins of 2.000 ± 0.002 mm. The loss due to a defective chip is $4. A sample of 25 chips was drawn from the production process and the results, in millimeters, can be found in the worksheet tab Prob. 7-13 in the Excel file C07Data file.
a. Compute the value of k in the Taguchi loss function.
b. What is the expected loss from this process based on the sample data?

Question 47

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5, etc.) to access the data.
Livelong, Inc.'s computer monitors have a failure rate of ? = 0.00095 units per hour. Assuming an exponential distribution, what is the reliability function? What is the probability of failure within 5,000 hours? Calculate your answer using the appropriate mathematical formula and verify your result using Excel.

Question 48

A blueprint specification for the thickness of a refrigerator part at Refrigeria, Inc. is 0.300 ± 0.025 centimeters (cm). It costs $25 to scrap a part that is outside the specifications. Determine the Taguchi loss function for this situation.

Question 49

What is the difference between inherent reliability and achieved reliability?

Question 50

How can product design affect manufacturability? Explain the concept and importance of design for manufacturability.

Question 51

Note: Data sets for several problems are available in the Excel workbook C07Data in the Student Companion Site for this chapter. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 7-5 , etc.) to access the data.
A hospital developed a design process consisting of the following steps: Plan, Design, Measure, Assess, and Improve. Below is a list of specific activities that comprise these five steps in random order. Place the activities in the most appropriate order within the correct step of the design process.
Pilot or test design
Submit proposal
Define measures to assess design performance
Implement design
Identify potential solutions to reduce out of control conditions
Develop business plan
Disseminate improvements throughout the organization
Monitor process performance
Select the best solution to improve control
Identify out-of-control conditions
Propose new concept
Create design to meet requirements
Identify new improvement opportunities
Monitor the new process design
Implement the best solution to improve control Verify proposal alignment with strategic objectives
Establish design team
Identify causes of out of control conditions
Analyze causes
Identify and validate customer requirements
Identify and evaluate best practices

Question 52

Investigate design-for-environment practices in some of your local industries. Describe company policies and the methods and techniques that they use to address environmental concerns in product design.

Question 53

In the production of Raphael Transformers, any output voltage that exceeds 120 ± 10 volts is unacceptable to the customer. Exceeding these limits results in an estimated loss of $200. However, the manufacturer can repair a defective unit by changing a resistor that costs $2.25.
a. Determine the Taguchi loss function.
b. Suppose the nominal specification is 120 volts. At what tolerance should the transformer be manufactured?

Question 54

An electronic component in a satellite radio has failure rate of ? = 0.000015 units/hour. Find the mean time to failure (MTTF). What is the probability (assuming an exponential probability distribution) that the component will not have failed after 12,000 hours of operation? Calculate your answer using the appropriate mathematical formula and verify your result using Excel.

Question 55

Using whatever "market research" techniques are appropriate, define a set of customer attributes for
a. Purchasing books at your college bookstore
b. A college registration process
c. A hotel room used for business
d. A hotel room used for family leisure vacations For each case, determine a set of technical requirements and construct the relationship matrix for the House of Quality.

Question 56

What is the purpose of detailed design?

Question 57

What is the definition of failure rate? How is it measured?

Question 58

Summarize the key design practices for high quality in manufacturing and assembly.

Question 59

Describe the steps of the product design and development process.

Question 60

A team was formed to study the refrigerator part at Refrigeria, Inc. described in Problem 6. While continuing to work to find the root cause of scrap, they found a way to reduce the scrap cost to $15 per part.
a. Determine the Taguchi loss function for this situation.
b. If the process deviation from target can be reduced to 0.015 cm, what is the Taguchi loss?

Question 61

At Elektroparts Manufacturers' integrated circuit business, managers gathered data from a customer focus group and found that any output voltage that exceeds 55 ± 2.5 volts was unacceptable to the customer. Exceeding these limits results in an estimated loss of $75. However, the manufacturer can still adjust the voltage in the plant using a quick diagnostic test that costs $2.00.
a. Determine the Taguchi loss function.
b. Suppose the nominal specification remains at 55 volts. At what tolerance should the integrated circuit be manufactured?

Question 62

The MTBF of an integrated circuit made by Outer Limits, Inc. is 18,000 hours. Calculate the failure rate.