How many levels of accuracy are there? What does IT8 mean?

The accuracy grade is divided into eight grades, namely IT0 1, IT0, IT 1, IT2 to IT 18, and the grade decreases from IT0 1 to IT 18. IT8: Indicates the accuracy of IT8.

1, the precision grade divided by the percentage of allowable error in dial scale value, the greater the number of precision grades, the greater the allowable error of dial scale limit value.

2. The larger the measuring range, the greater the allowable error of the absolute value of the measured pressure at the same accuracy level. ?

The commonly used precision is 2.5, 1.5. If it is 1.0 and 0.5, it belongs to high precision, and now some figures have reached 0.25.

Extended data:

Accuracy grade refers to the classification and grade of measuring instruments that meet certain measurement requirements and keep the error within the prescribed limits. GeneRally, the machining accuracy is about 0. 1 mm, and the surface roughness ra is 0.3-0.8 micron, such as turning, milling and planing, which is suitable for the manufacture of automobiles and tractors.

The precision of ultra-precision machining is 0. 1-0.0 1 micron, and the surface roughness ra is 0.03-0.05 micron, such as ultra-precision cutting with diamond tools, ultra-precision abrasive machining, ultra-precision special machining and composite machining.

Baidu Encyclopedia-Accuracy Level