SCMT Exam 2 - FLASHCARDS - Chapter 13

Question 1

What is variation that is inherent in the process itself?

Answer 1

Common variation

Question 2

The range of values in a measure associated with a process that is allowable given the intended use of the product is known as which of the following?

Answer 2

Specification limits

Question 3

According to Genichi Taguchi,as customers get more demanding, there is pressure to reduce

Answer 3

Variability

Question 4

The _____ is used to measure how well our process is able to produce relative to the design specifications

Answer 4

Capability index

Question 5

Common variation is often referred to as ______

Answer 5

Random variation

Question 6

True or false: It is generally accepted that as variation is reduced, quality is improved

Answer 6

TRUE

Question 7

If the design specifications are 10.00 inches ± 0.2 inch, then 10.20 is the _____ specification limit.

Answer 7

Upper

Question 8

What does Taguchi say about about specifications?

Answer 8

Being within specification is a continuous function

Being within specification is not a yes/no decision

Question 9

When the mean and standard deviation of the process are operating such that the upper and lower control limits are acceptable relative to the upper and lower specification limits, we say the process is

Answer 9

Capable

Question 10

To generate a Cpk value of 1.00, the design limits must be _____ standard deviation(s) away from the process mean.

Answer 10

3

Question 11

A traditional way of interpreting such a specification is that any part that falls within the allowed range is equally
______, whereas any part falling outside the range is totally ______

Answer 11

Good; bad

Question 12

Because the process mean can shift in either direction, the direction of shift and its distance from the design specification set the limit on the process capability. The direction of shift is toward the ______ number.

Answer 12

Smaller

Question 13

Which distribution is used to calculate the probability of producing a defect?

Answer 13

Normal

Question 14

According to Genichi Taguchi, from the customer’s view, there is often practically no difference between a product just ______ specifications and a product just ______

Answer 14

Inside; outside

Question 15

With a process control chart, what does it indicate when one point is below the LCL?

Answer 15

The process is out of control

Question 16

The ______ shows how well the parts being produced fit into the range specified by the design specification limits.

Answer 16

Capability index

Question 17

Which of the following is the control chart that measures the fraction defective of each individual sample tested?

Answer 17

P chart

Question 18

Which of the following are typical objectives of process control plans?

Detect shifts in the process

Provide information about whether items are meeting design specifications

Identify new design specifications

Develop new processes

Answer 18

Detect shifts in the process

Provide information about whether items are meeting design specifications

Question 19

What is used to measure how well our process is capable of producing relative to the design specifications?

Answer 19

Capability index

Question 20

A rule of thumb when setting up a p-chart is to make the sample large enough to expect to count the attribute ______ in each sample?

Answer 20

Twice

Question 21

To generate a Cpk value of 2.00, the design limits must be _____ standard deviation(s) away from the process mean

Answer 21

6

Question 22

With a process control chart, what does it indicate when there is a run of five points below the center line?

Answer 22

The process is out of control

Question 23

The underlying distribution for the c-chart is which of the following?

Normal

Poisson

Gamma

Exponential

Answer 23

Poisson

Question 24

What formula is used to calculate the LCL?

Answer 24

p
- z sp or 0 if less than 0

Question 25

Measuring the torque and horsepower of a motor is known as sampling by

Answer 25

Variables

Question 26

Which of the following charts is used when the measure for the sample is weight, volume, number of inches or other variable measurements? C chart Range chart Mean chart P chart

Answer 26

Range chart and mean chart

Question 27

Which of the following control charts must make the sample large enough to allow counting of the attribute?

Answer 27

P chart

Question 28

Sample sizes of _____ or _____ units seem to be the preferred numbers for sample sizes of x-bar charts.

Answer 28

four or five

Question 29

What is the minimum number of samples suggested for control charts with variable measurement?

Answer 29

25

Question 30

Usually, it is best to start off with _____ sampling of a process and taper off as _____ in the process builds.

Answer 30

Frequent; confidence

Question 31

The standard practice in statistical process control for variables is to set control limits how many standard deviations from the mean?

Answer 31

Three

Question 32

When the product or service can have more than one defect per unit, which of the following is the most appropriate chart?

Answer 32

C chart

Question 33

Which of the following indicates the process is out-of-control? A point is below the lower control limit A point is above the upper control limit A point is near the center line of the chart

Answer 33

A point is below the lower control limit A point is above the upper control limit

Question 34

If the lower control limit for the c-chart is negative, then which of the following values should be used?

Answer 34

0

Question 35

What is Statistical Quality Control (SQC)?

Answer 35

uses statistics & control charts to tell when to adjust a process?

Question 36

What is Statistical Quality Control (SQC) used for?

Answer 36

Used to: – Control the process as products/services are produced – Inspect samples of finished products/services

Question 37

What is the objective of SQC?

Answer 37

Provide statistical signal when assignable causes of variation are present

Question 38

What does statistical quality control involve?

Answer 38

1. Creating standards (upper & lower limits) 2. Measuring sample output (e.g. mean wgt.) 3. Collecting, organizing, and interpreting data 4. Taking corrective action (if necessary)

Question 39

What is statistical process control (SPC)?

Answer 39

Statistical technique for testing a random sample of output to ensure process is making product (or service) to standard

Question 40

What is the variation of SPC?

Answer 40

Random and inherent in the process itself (Natural Causes)

Question 41

What are specification design limits?

Answer 41

Limits imposed by enginerring in the product’s design (someone outside your company)

Question 42

What are control (process) limits?

Answer 42

Limits within which the process operates for a specified (very high) percentage of the time (typically x ± 3* sigma).

Question 43

What is the upper specification?

Answer 43

The maximum acceptable value for a characteristic

Question 44

What is the lower specification?

Answer 44

The minimum acceptable value for a characteristic

Question 45

How do we know if a process is capable?

Answer 45

A process is capable if its upper and lower control limits are within the upper and lower specification limits

Question 46

What is the range of values allowed divided by the range of values produced?

Answer 46

Process capability index (Cpk)

Question 47

Is Cpk a relative measure?

Answer 47

No

Question 48

What are characteristics of a variable chart?

Answer 48

• Quantities that you measure, e.g., weight, length • May be in whole or in fractional numbers • Continuous numerical data. Examples are X bar or R charts

Question 49

What are characteristics of an attribute chart?

Answer 49

• Characteristics for which you focus on defects • Products are either ‘good’ or ‘bad’, or count number of defects • Categorical or discrete numerical data. Examples are P or C charts

Question 50

What type of chart is used when an item or service is either good or bad (a yes‐no decision, or attribute characteristic)?

Answer 50

P chart

Question 51

What type of chart is used to monitor the number (or count) of defects per unit? – When an item (or service) may have multiple defects

Answer 51

C chart

Question 52

What type of chart shows sample means over time?

Answer 52

X bar chart

Question 53

What type of chart monitors process average?

Answer 53

X bar chart

Question 54

What type of chart shows sample ranges over time?

Answer 54

R chart

Question 55

What type of chart monitors variability in a process?

Answer 55

R chart

Question 56

How should samples be for X bar and R charts?

Answer 56

Preferable to keep small (usually 4 or 5 units)

Question 57

What are solutions for losing control?

Answer 57

1. Redesign the process so that it can achieve the desired output 2. Use an alternate process that can achieve the desired output 3. Retain the current process but attempt to eliminate unacceptable output using 100 percent inspection 4. Examine the specifications to see whether they are necessary or could be relaxed without adversely affecting customer satisfaction.

Question 58

What is acceptance sampling?

Answer 58

Performed on goods that already exist to determine what percentage of the products conform to specifications – Determine quality level – Ensure quality is within predetermined level

Question 59

What are disadvantages of acceptance sampling?

Answer 59

• Risks of accepting “bad” lots and rejecting “good” lots • Added planning and documentation • Sample provides less information than 100 percent inspection

Question 60

What are advantages of acceptance sampling?

Answer 60

• Economy • Less handling damage • Fewer inspectors • Upgrading of the inspection job • Applicability to destructive testing • Entire lot rejection (motivation for improvement)

Question 61

True or false: Acceptance sampling is performed on goods that already exist to determine what percentage of items conforms to specifications?

Answer 61

TRUE

Question 62

True or false: It is impossible to have zero variability in production processes?

Answer 62

TRUE. As noted in class, it is impossible to have zero variability

Question 63

For which of the following should we use an R-chart to monitor process quality? A. Weighing trucks at a highway inspection station to determine if they are overloaded B. Deciding whether an airliner has sufficient fuel for its trip C. Student grades measured from 1 to 100 D. Determining whether vehicles from a motor pool will run E. Determining the accuracy of a forecast of "snow"

Answer 63

Student grades measured from 1 to 100. We are looking at things that have continuous types of numbers. In attribute sampling, we determine whether something is good or bad, fits or doesn't fit—it is a go/no-go situation. In variables sampling we measure the actual weight, volume, number of inches, or other variable measurements, and we develop control charts to determine the acceptability or rejection of the process based on those measurements. X-bar and R-charts are used with variable measurements

Question 64

You are developing an X-bar chart based on sample means. You know the standard deviation of the sample means is 100, the desired confidence level is 99.7 percent, and the average of the sample means is 400. Which of the following is your UCL? A. 500 B. 300 C. 600 D. 200 E. None of these

Answer 64

None of the above. From the notes (and book), we know the rule of thumb z = 3 (which is the 99.7% level). Using Equation 13.12 from the book, X-bar = 400, standard deviation = 100 and z = 3. UCL = 400 + (3 x 100) = 700