How should the quality of granite square rulers be judged?

Verification method for quality of granite square ruler

☆ Polish the large board

1) Thickness tolerance measurement method

Use a vernier caliper with a reading of 0.1mm to measure the midpoint of the four edges. Use the difference between the larger and smaller thickness values on the same board to indicate poor thickness. The contract stipulates that the thickness of the board is 20MM, and the allowable deviation is plus or minus 1MM.

2) Measurement method for flatness plate tolerance

Measure with a steel ruler with a reading of 0.1mm and a length of 1000mm. Place the steel ruler on the two diagonal corners of the plate and use a feeler gauge to measure the gap between the ruler surface and the plate surface. The contract stipulates that the plane tolerance of the TodayHot board is 0.80MM

3) Measurement methods for length and width

Measure with a steel ruler reading 1MM. Measure three straight lines for length and width respectively, and use the average value as the standard. Record the length and width of the board for later quantity calculation.

☆ Floor slabs

1) Thickness tolerance measurement method

Use a vernier caliper with a reading of 0.1mm to measure the midpoint of the four edges. Use the difference between the larger and smaller thickness values on the same board to indicate poor thickness. The contract stipulates that the floor thickness is 10MM, and the allowable deviation is plus or minus 0.50mm.

2) Measurement method for flatness tolerance

Measure with a 0.1mm steel ruler, place the ruler on the two diagonal corners of the plate, and use a feeler gauge to measure the gap between the ruler surface and the plate surface. The contract stipulates that the floor plan tolerance is plus or minus 0.20MM

3) Measurement methods for length and width

Measure with a steel ruler reading 1MM. Measure three straight lines for length and width respectively, and use the average value as the standard. The length and width tolerance of the floor specified in the contract is -1mm, and the floor is 305x305mm

4) Allowable angle tolerance

Measure with a 90 degree steel ruler and a feeler gauge with an internal angle perpendicularity tolerance of 0.13mm and an internal angle side length of 450x400mm. Place the two sides of the angle ruler tightly against the two edges of the board, and use a feeler gauge to measure the gap between the board and the edge of the angle ruler. Measure the four corners of the board using this method. The allowable tolerance for the angle specified in the contract is 0.40mm.