Term
|
Definition
| Refers to the ability to hit what is aimed at (the bull’s eye of a target. (Need to know the difference b/t accuracy and precision) |
|
|
Term
|
Definition
| The intentional, desired difference between the dimensions of two mating parts. It is the difference between the dimensions of the largest interior fitting part (shaft) and that of the smallest exterior-fitting part (hole). |
|
|
Term
|
Definition
| Provide The basis for all other units of measurement. As shown in figure 1, this refers to the units used for electric currents. Base SI unit = (A) |
|
|
Term
|
Definition
| One of the two ways inspections can be done. Using gages to determine if the product is good or bad, resulting in a yes or no, go or not-go decision. |
|
|
Term
|
Definition
| Provide The basis for all other units of measurement. As shown in figure 1, this refers to the units used for Luminous intensity. Base SI unit = (cd) |
|
|
Term
|
Definition
| One of the three classes of fits in the ISO system of Limits and Fits. In the minimum sense, this would be the difference between the smallest hole and the largest shaft. The clearance should be determined by the designer. |
|
|
Term
| Coordinate Measure Machine |
|
Definition
| Makes precision measurements in three-dimensional Cartesian coordinate space (CMM) Parts are placed on a large granite flat or the table. The vertical arm carries a probe which can be precisely moved in the x-y-z directions to produce 3D measurements. |
|
|
Term
|
Definition
| AKA Stabilty... Answers the question of how well a device retains its calibration over period of time. As devices become more accurate they usually loose this and become more sensitive to small changes in temperature and humidity. |
|
|
Term
|
Definition
| Provide industry with linear standards of high accuracy that are necessary for everyday use in manufacturing plants. They are small, rectangular, square, or round in the cross section and are made from steel or carbide with two very flat and parallel surfaces that are certain specified distance apart. Figure 10.3 |
|
|
Term
|
Definition
| States the maximum allowable deviation of a form or a position from the perfect geometry implied by a drawing. These tolerances specify the diameter or the width of a tolerance zone necessary for part to meet its required accuracy . |
|
|
Term
|
Definition
| Interference bands can be used to measure the size of objects to great accuracy. Out of phase waves produce dark bands. Each dark band indicates a change of one-half wavelength in the elevation. Each interference band represents 11.6 micro-inches or .295 micrometers. |
|
|
Term
|
Definition
| With clearance fits, largest shaft is smaller than the smallest hole, whereas with interference fits, the hole is smaller than the shaft. |
|
|
Term
|
Definition
| Permits accuracies of plus or minus 0.5 part per million over a distance of 6.1 m with 0.01 micrometer resolution. Useful in checking the movement of machine tool tables, aligning and checking large assembly jigs, and making measurements of intricate machined parts such as tired-tread molds. |
|
|
Term
|
Definition
| The term used to designate the direction of the predominate surface pattern produced by the machining process. |
|
|
Term
|
Definition
| Base name, meter or metre. The linear extent in space from one end to the other; the longest dimension of something that is fixed in place. (See Table 10-1, pg. 190 for a very specific numerical value) |
|
|
Term
|
Definition
| This factor refers to the calibration accuracy of the device over its full working range. Is it linear? To what degree? Where does it become nonlinear? |
|
|
Term
|
Definition
| The simples and most common direct-reading linear measuring instrument is the machinist’s rule. Figure 10-13 pg205. The machinist’s rule is an end- or line-matching device. An end and a line, or two lines, must be aligned with the extremities of the object or the distance being measured. Such scales are not ordinarily used for accuracies greater than 1/64 in. (.01 in.) or about 1/2 mm. |
|
|
Term
|
Definition
| Often confused with resolution but it is not the same thing - The amplification of the output portion of the device over the actual input dimension. The more accurate the device, the greater must be its magnification factor, so that the required measurement can be read out and compared with the desired standard. |
|
|
Term
|
Definition
| Measured in kilograms and is one of the four fundamental measures |
|
|
Term
|
Definition
| Basic linear measurements and the attributes and variables devices most commonly found in a company’s quality control facility |
|
|
Term
|
Definition
| One of the most widely used measuring devices - fixed anvil and a movable spindle. one revolution moves the spindle this distance : 0.025in |
|
|
Term
|
Definition
| Large optical device on which both linear and angular measurements can be made. Can be moved in X and Y directions by accurate micrometer screws |
|
|
Term
|
Definition
| Most common type of fixed gage. Accurately ground cylinders used to gage internal dimensions, such as holes. |
|
|
Term
|
Definition
Precision
Refers to the repeatability of the process. |
|
|
Term
|
Definition
| Sometimes call sensitivity and refers to the smallest unit of scale or dimensional input that the deice can detect or distinguish. The greater the resolution of the device, the smaller will be the things it can resolve and the greater will be the magnification required to expand these measurements up to the point where they can be observed by the naked eye. |
|
|
Term
|
Definition
| Used to check shafts or other external round members. These are also made in go and no-go types. |
|
|
Term
|
Definition
| The measurement device (or working gage) should be 10 times more precise than the tolerance to be measured. - the master gage should be 10 times more precise than that of the inspection device. |
|
|
Term
|
Definition
| May be used to obtain accurate angle measurements if the physical conditions will permit. Consists of an accurately ground bar on which two accurately ground pins of the same diameter are mounted an exact distance apart. usually either 5 or 10 in. |
|
|
Term
|
Definition
| Most common type of fixed gage for measuring external dimensions - rigid u shaped frame on which are two or three gaging surfaces, usually made of hardened stell or tungsten carbide. |
|
|
Term
|
Definition
| How well does the device retain its calibration over a period of time - also called drift. As devices become more accurate, they often lose stability and become more sensitive to small changes in temperature and humidity. |
|
|
Term
|
Definition
| Capable of measuring at 0.0001 in. when equipped with an indicator that shows that a selected pressure between the anvils has been obtained. |
|
|
Term
|
Definition
| Refers to the finely spaced surface irregularities. It results from machining operations in the case of machined surfaces. |
|
|
Term
|
Definition
| the continuum in which events occur in succession from the past to the present and on to the future. It is a one-dimensional quantity used to sequence events, to quantify the durations of events and the intervals between them. |
|
|
Term
|
Definition
| an undesirable but permissible deviation from a desired dimension. There is variation in all process, and no part can be made exactly to a specified dimension, except by chance. |
|
|
Term
|
Definition
| similar to an optical flat but is made out of steel and usually has only one surface that is accurate. It is used to accurately determine the size of an object. |
|
|
Term
|
Definition
| a versatile instrument that measures by optical means; no pressure is involved. It is very useful for making accurate measurements on small or delicate parts. |
|
|
Term
|
Definition
| an end-measuring instrument, available in various sizes, that can be used to make both outside and inside measurements to theoretical accuracies of 0.01 mm or 0.001 in. |
|
|
Term
|
Definition
| this type of machine vision is used for visual inspection, for guidance and control, or for both. Normal TV image formation on photosensitive surfaces or arrays is used, and the video signals are analyzed to obtain information about the object. |
|
|
Term
|
Definition
| surface irregularity of greater spacing than in roughness. It may be the result of warping, vibration, or the work being deflected during machining. |
|
|
