TU07_BasicMeasurement Vocab Flashcards
Accuracy
The difference between a measurement reading and the true value of the measured dimension. The smaller the difference, the greater the this would be for the reading.
Attribute Inspection
A type of inspection that uses a device with an established standard size to determine whether a measurement falls within the acceptable tolerance range. Also known as gaging, determines whether a part passes or fails inspection.
Calibrate
To compare and adjust a device with unknown accuracy to a device with a known, accurate standard. Inspectors would do this to measure devices to eliminate any variation in the device being checked.
Discrimination
The smallest unit of measurement that an instrument is capable of displaying. Also known as resolution or least count, affects how accurate an instrument’s measurement readings can be.
Gaging
A type of inspection that uses a device with an established standard size to determine whether a measurement falls within the acceptable tolerance range. Also known as attribute inspection, determines whether a part passes or fails inspection.
Granite
A dense, hard type of rock that exhibits excellent wear resistance, stability, and flatness. Its tables and surface plates are used for inspection surfaces and reference planes.
Inspection
The examination of a part during or after its creation to confirm that it adheres to specifications. During this, defects may be identified and corrected.
Mastering
A quick check of a measuring device against a known standard reference, such as a gauge block, to determine if the device is providing accurate measurements.
Liquid Crystal Display
LCD. A light-driven display device made from nematic liquid sealed between two pieces of polarized glass. Some digital height gages and other digital measuring devices have a liquid crystal display screen to show readings electronically.
Nominal
A stated measurement that may not correlate exactly with a physical part. This type of measurement for a part indicates the size specified in the part print, which may differ from the size of the actual part.
Precision
The degree to which an instrument will repeat the same measurement over a period of time. It is also called repeatability because precise instruments will provide the same results under unchanged conditions.
Reference Plane
A common surface is chosen as a point of reference for measuring the dimensions of tools or manufactured parts. These surface plates are commonly used as reference planes for height gages and other tools since their dimensions do not change significantly due to thermal expansion.
Resolution
The smallest unit of measurement that an instrument is capable of displaying. It also known as discrimination or least count, affects how accurate an instrument’s measurement readings can be.
Sensitivity
The smallest amount of force or pressure that a measuring instrument is capable of detecting. This can improve the accuracy of measuring instruments but can decrease precision due to the likelihood of operator error.
Ten-To-One Rule
The inspection guideline states that the accuracy and resolution of an inspection instrument must be equal to one-tenth of the required tolerance of the inspected part feature. According to this rule, a feature with a tolerance to the thousandth place must be measured by an instrument with an accuracy rating and resolution to the ten-thousandth place.
Thermal Expansion
An increase in size as a material increases in temperature. This is a measuring instrument components that is undesirable and can cause inaccurate measurements.
Variable Inspection
An unwanted but acceptable variation or deviation from a desired dimension of a part. A dimension that is within an acceptable tolerance range will still meet specifications.
Variance
The degree of deviation between one measurement result and the next when the same object is measured. This is between consecutive inspection measurements indicates low measurement precision.
