1. Instrument working conditions: The instrument works at 15~25 °C.
2. Appearance: The working surface of the instrument shall not have blisters, blowholes, bumps, scratches, burrs, rust and other defects that affect the use; bare exposed non-working surfaces shall not have stomata, blisters, cracks, rust and other obvious defects. The plating layer of the instrument should be even and smooth. The painted surface of the instrument must not have obvious defects such as stripping, spots, scratches and uneven color. It should be clear that all the lines, numbers and signs of the instrument should be clear. The connection between the sensor and the indicator (or display) and the connector should be intact and reliable, and the plastic casing and handle surface of the instrument should be uniform in color, smooth and beautiful, and free of defects such as bubbles and cracks.
3. Tilt change: When the instrument sensor is evenly tilted, the indicator (or display) should be able to change smoothly accordingly; the instrument zero-position device and the extended-range device work smoothly and reliably.
4. Requirements for parts: The surface roughness Ra of the working surface of the grinding instrument should be no more than 0.4μm; the fitting point of the working surface of the scraping instrument should not be less than 25 points within the range of 25mm×25mm.
5. The hardness of the working face of the instrument shall not be less than 180HB.
6. The instrument should be subjected to high temperature test, low temperature test and continuous impact test under transportation and packaging conditions.