1mm (millimeter) is equal to 100 wires. In mechanical dimensional measurement, one millimeter is usually divided into hundredths, and the length unit represented by one part is called a trace. A trace is 0.01 mm and 10 microns.
Classification and use of measuring instruments
1. Class A measuring instruments
1. The highest measuring standard instrument, mainly used for transmitting quantitative values.
2. Important measuring instruments, mainly used to detect the Class A quality characteristics of products.
3. Measuring instruments used as the basis for calibration according to the accuracy level specified by the state.
4. Work measuring instruments used in trade settlement, safety protection, medical and health care, and environmental monitoring, and are included in the national compulsory verification catalog.
2. Class B measuring instruments
1. Working measuring instruments used for energy and material accounting.
2. Various working measuring instruments and reference materials for production technology, process parameters and quality status control.
3. Work measuring instruments used for product inspection, measurement and testing, such as micrometer, vernier, table measuring tools and special measuring tools.
4. Various testing instruments used to detect the Class B quality characteristics of products.
5. Standard physical samples used for comparative measurement of product process parameters.
3. Class C measuring instruments
1. Various indicating instruments that are matched with the production equipment, are not easily disassembled, and only have an indication function.
2. General panel meters and measuring instruments used for monitoring have no direct impact on product measurement.
3. Measuring instruments without precision requirements used in production and daily life.