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SCMT 364 > SCMT Exam 2 - FLASHCARDS - Chapter 13 > Flashcards

SCMT Exam 2 - FLASHCARDS - Chapter 13

1
Q

What is variation that is inherent in the process itself?

A

Common variation

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2
Q

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?

A

Specification limits

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3
Q

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

A

Variability

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4
Q

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

A

Capability index

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5
Q

Common variation is often referred to as ______

A

Random variation

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6
Q

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

A

TRUE

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7
Q

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

A

Upper

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8
Q

What does Taguchi say about about specifications?

A

Being within specification is a continuous function

Being within specification is not a yes/no decision

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9
Q

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

A

Capable

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10
Q

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

A

3

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11
Q

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 ______

A

Good; bad

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12
Q

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.

A

Smaller

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13
Q

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

A

Normal

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14
Q

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

A

Inside; outside

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15
Q

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

A

The process is out of control

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16
Q

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

A

Capability index

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17
Q

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

A

P chart

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18
Q

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

A

Detect shifts in the process

Provide information about whether items are meeting design specifications

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19
Q

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

A

Capability index

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20
Q

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?

A

Twice

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21
Q

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

A

6

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22
Q

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

A

The process is out of control

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23
Q

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

Normal

Poisson

Gamma

Exponential

A

Poisson

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24
Q

What formula is used to calculate the LCL?

A

p
- z sp or 0 if less than 0

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25
Q

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

A

Variables

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26
Q

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

A

Range chart and mean chart

27
Q

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

A

P chart

28
Q

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

A

four or five

29
Q

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

A

25

30
Q

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

A

Frequent; confidence

31
Q

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

A

Three

32
Q

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

A

C chart

33
Q

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

A

A point is below the lower control limit

A point is above the upper control limit

34
Q

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

A

0

35
Q

What is Statistical Quality Control (SQC)?

A

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

36
Q

What is Statistical Quality Control (SQC) used for?

A

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

37
Q

What is the objective of SQC?

A

Provide statistical signal when assignable causes of variation are present

38
Q

What does statistical quality control involve?

A
  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)
39
Q

What is statistical process control (SPC)?

A

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

40
Q

What is the variation of SPC?

A

Random and inherent in the process itself (Natural
Causes)

41
Q

What are specification design limits?

A

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

42
Q

What are control (process) limits?

A

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

43
Q

What is the upper specification?

A

The maximum acceptable value for a characteristic

44
Q

What is the lower specification?

A

The minimum acceptable value for a characteristic

45
Q

How do we know if a process is capable?

A

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

46
Q

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

A

Process capability index (Cpk)

47
Q

Is Cpk a relative measure?

A

No

48
Q

What are characteristics of a variable chart?

A

• 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

49
Q

What are characteristics of an attribute chart?

A

• 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

50
Q

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

A

P chart

51
Q

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

A

C chart

52
Q

What type of chart shows sample means over time?

A

X bar chart

53
Q

What type of chart monitors process average?

A

X bar chart

54
Q

What type of chart shows sample ranges over time?

A

R chart

55
Q

What type of chart monitors variability in a process?

A

R chart

56
Q

How should samples be for X bar and R charts?

A

Preferable to keep small (usually 4 or 5 units)

57
Q

What are solutions for losing control?

A
  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.
58
Q

What is acceptance sampling?

A

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

59
Q

What are disadvantages of acceptance sampling?

A

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

60
Q

What are advantages of acceptance sampling?

A

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

61
Q

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

A

TRUE

62
Q

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

A

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

63
Q

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”

A

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

64
Q

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

A

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

SCMT 364 (8 decks)

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