Term
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Definition
[(x-bar-LTL)/(3*s) ; (UTL-x-bar)/(3*s)]
Used to ascertain how well process is performing in relation to target dimension. |
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Term
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Definition
(UTL-LTL)/(6*s)
Shows how well parts produced from a process fit into the design (tolerance) limits. |
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Term
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Definition
| Sampling to accept or reject the immediate lot of product at hand. |
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Term
| Purposes of Acceptance Sampling |
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Definition
Determine quality level
Ensure quality is within predetermined level |
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Term
| Advantages of Acceptance Sampling |
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Definition
Economy
Less handling damage
Fewer inspectors
Upgrading of the inspection job
Applicability to destructive testing
Entire lot rejection (motivation for improvement) |
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Term
| Disadvantages of Acceptance Sampling |
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Definition
Risk of accepting bad lots and rejecting good lots
Added planning and documentation
Sample provides less info than 100% inspection |
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Term
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Definition
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Term
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Definition
| refers to the acceptability of procuct across a range of characteristics. Attribute sampling |
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Term
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Definition
refers to the # of unacceptable conditions per unit - may be higher than the number of defectives.
Attibute data |
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Term
| Variable (continuous) data |
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Definition
| usually measured by the mean and the standard deviation. |
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Term
| Goal of Acceptance Sampling |
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Definition
(1) determine how many units, n, to sample from a lot
(2) determine the maximum # of defective items, c (acceptance #), that can be found in the sample before the lot is rejected. |
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Term
| AQL (acceptable quality level) |
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Definition
| max acceptable percentage of defectives defined by the PRODUCER |
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Term
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Definition
| the probability of rejecting a good lot |
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Term
| LTPD (lot tolerance percent defective) |
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Definition
| the percentage of defectives that defines the consumer's rejection point |
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Term
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Definition
| the probability of accepting a bad lot by the consumer |
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Term
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Definition
| variability built into the system |
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Term
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Definition
occurs because some element of the system or some operating conditions are out of control
-Quality control seeks to identify when assignable variation is present so that corrective action can be taken. |
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Term
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Definition
| measuring a variable that can be SCALED such as weight, length, temperature, and diameter. |
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Term
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Definition
| determining the existence of a characteristic such as acceptable-defective, timely-late, and right-wrong |
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Term
| Control Chart Assumptions |
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Definition
-repetitive operation will not produce exactly the same outputs
-pattern of variability often described by a normal distribution
-Random samples that fully represent the population being checked are taken
-Sample data plotted on control charts to determine if the process is still under control. |
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Term
| What % of our observations would we expect to fill within +/- 3 standard deviations |
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Definition
| +/- 3 standard devations expects 99.7 % of our observations to fall within these limits |
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Term
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Definition
based on attribute measurements
p-bar = total # of defectives/total # of observations
UCL = p-bar + Z*s
LCL = p-bar - Z*s |
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Term
| x-bar chart control limits |
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Definition
UCL = x-double bar + A2*R-bar
LCL = x-double bar - A2*R-bar |
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Term
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Definition
UCL = D4*R-bar
LCL = D3*R-bar |
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Term
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Definition
| measures the extent to which an organization's production system can meet design specifications |
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Term
| Result of TQM's emphasis on "making it right the first time" |
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Definition
| This has resulted in organizations emphasizing the ability of a production system to meet design specifications rather than evaluating the quality of outputs after the fact with acceptance sampling |
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Term
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Definition
| determined from manufacturing process data |
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Term
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Definition
| specified in engineering design drawing |
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Term
| What does the Process Capability depend on? |
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Definition
-Location of the process mean
-Natural variability inherent in the process
-Stability of the process
-Product's design requirements (therefore a process is capable "when the mean and standard deviation are =" |
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Term
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Definition
| within six sigma quality when there are fewer than 3.4 defective parts per million. This corresponds to a process capability ratio/index of 2 |
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