The plane thickness of the large cast iron plate is about 30~35cm, the medium cast iron plate is about 25cm, and the small cast iron plate is about 10~20cm.

The measurement section should be a representative section on a surface plate, such as two diagonal lines, four side lines, two center lines.

There should be no rust, scratches, bruises and other appearance defects that affect the use of the work surface.

Excavate the metal in the defective area, use the same or compatible electrode as the base metal to weld the defective area, smooth after welding and perform post-weld heat treatment.

Process the datum surface parts first. Because the surface is used as the positioning datum during the machining process, so as to provide a precise datum for the subsequent processing as soon as possible.

There is too much slag or not cleaned in the molten iron , and the slag is not paid attention to when pouring.