ASME B89.1.13 pdf download.MICROMETERS.
ASME B89.1.13 is intended to provide the essential requirements for micrometers as a basis for mutual understanding between manufacturers and consumers. Outside, inside, and depth micrometers are described in the Standard.
2 DEFINITIONS
backlash: a relative movement between interacting mechanical parts, resulting from looseness [ASME B5.54M-1992 (Rl998). In this Standard, backlash is further defined as the rotation of the spindle, in. the opposite direction of the initial reading, before spindle moves in a linear direction. This condition is typically caused by looseness of fit between the lead screw and adjusting nut.
bias: systematic error of the indication of a measuring instrument (VIM).
eccentricity: the distance between the geometric center or axis of the body and its axis of rotation.
end shake: the amount of spindle movement, when an axial force is applied in the direction of the spindle alternating towards the anvil and away from the anvil, without rotating the spindle.
error (of indication) of a measuring instrument: indication of a measuring instrument minus a true value of the corresponding quantity (VIM).
NOTE: This concept applies mainly where the instrument is compared to a reference sandard.
flatness: the condition of a surface having all elements in one plane (ASME Y14.5M-1994).
maximum permissible error (MPE): extreme values of an error permitted by specifications, etc., for a given measuring instrument (VIM).
parallelism: the condition of a surface or center plane, equidistant at all points from a datum plane or axis, equidistant along its length from one or more datum planes or a datum axis (ASME Y14.5M-1994).
A2.4 Friction or Ratchet Stop
Friction or ratchet stops on micrometers provide a uniform force when making measurements. The accuracy and repeatability is generally better when using friction or ratchet stops.
A25 Micrometer Stand
While one-hand operation is a common practice, the use of the micrometer stand is recommended when more accurate measurements are required. It allows the operator to free both hands and generally lowers the uncertainty of the measurements.
A2.6 How to Read the Micrometer
A2.6.1 Micrometer, Outside, Inch, 0.001 in. Resolution. Graduations are engraved on the adjustable sleeve and graduated thimble of a micrometer. The adjustable sleeve is graduated in 40 equal parts with each line representing 0.025 in., which corresponds to one thread of the micrometer spindle. The numbers on the adjustable sleeve, 1, 2, and 3, represent 0.100 in., 0.200 in., and 0.300 in., respectively. The graduated thimble has 25 lines on its circumference, each line representing 0.001 in. The numbers on the graduated thimble, 1, 2, 3, and 5, represent 0.001 in., 0.002 in., 0.003 in., and 0005 in., respectively.
A2.6.2 Micrometer, Outside. Metric. 0.01-mm Reading. Graduations are engraved on the adjustable sleeve and graduated thimble of a micrometer. The adjustable sleeve is graduated in 50 equal parts, with each line representing 0.5 mm, which corresponds to one thread of the micrometer spindle. The numbers on the adjustable sleeve, 5, 10, 15, represent 5 mm, 10 mm, and 15 mm, respectively. The graduated thimble has 50 lines on its circumference, with each line representing 0.01 mm. The numbers on the graduated thimble, 5, 10, 15, and 30, represent 0.05 mm, 0.10 mm, 0.15 mm, and 0.30 mm, respectively.
B3.4 Difference due to Dissimilar Materials
If parts made of aluminum or magnesium are checked by steel gages, an allowance for temperature differences, with reference to 20°C (68°F), must be made as the expansion coefficient of aluminum is approximately twice that of steel, while the coefficient of magnesium is even greater.
83.5 Soak Time
Gages should be stored in a constant temperature room before they are inspected to ensure they are nearly the same temperature as the measurement laboratory. The amount of soak 4ime required depends on the size of the gage and the desired accuracy.
B4 HUMIDITY
The relative humidity of the atmosphere in a gage laboratory should preferably be kept under 45% to minimize the possibility of corrosion. In general, the air conditioning system of a laboratory should remain in operation at all times. This is both because the change in humidity may cause corrosion and because there are delays while instruments and gages reach the proper temperature on the day when the laboratory is reopened.
B5 CLEANLINESS
Cleanliness is an important requirement for a good gage laboratory. Small particles of dirt may cause serious errors in precision measurements and bring about excessive wear of precision instruments.
ASME B89.1.13 pdf download
