Asme b89 3 7 defines standardized tolerance grades for surface plates.
Granite surface plate grades.
The middle grade plates grade a are often used in inspection areas.
Our granite surface plates are manufactured in three ledge types as well as standard sizes and grades.
Granite surface plate have more rigidity for the same depth with the absence of corrosion.
Cast iron surface.
Grade b plates are the lowest accuracy plates and they might be found on shop floors.
The overall flatness specifications of standridge granite products meet and surpass the requirements set forth by the federal.
Flatness is define by the distance between peak and depth point of surface.
Laboratory grade aa and a room inspection grade b and the fourth is workshop grade.
Plates that have ledges are used for clamping purposes only.
Workshop grades being the least flat and as the name suggests they are intended for use in tool rooms.
Types of surface plate.
The highest accuracy plates are called grade aa and they are often found in calibration laboratories.