Reason:
1. The operator's manual operation is not accurate, and the manual operation number is incorrect.
2. There are burrs around the mold.
3. The centring rod is magnetic.
4. The four sides of the mold are not vertical.
Improvement:
1. The manual operation shall be carefully checked repeatedly, and the points shall be at the same point and height as far as possible.
2. Use oilstone or file to deburr the periphery of the mold, wipe it with rags, and then confirm by hand.
3. Demagnetize the centring rod before centring the mold (ceramic centring rod or others can be used).
4. Check whether the four sides of the mold are vertical by the calibration table (if the perpendicularity error is large, review the plan with the fitter).
