AS 1004.2-1998 pdf free.Surface Plates For Metrology – Part2:Granite.
This part of ISO 8512 specifies requirements for rectangular or square granite surface plates ranging from 160 mm x 100 mm to 2500 mm x 1600 mm, as preferred sizes, in four grades of accuracy 0, 1, 2 and 3.
NOTE 1 Granit& is a commonly used description; a more specific description is given in clause 4.
This part of ISO 8512 applies to new granite surface plates, granite surface plates in use, and those reconditioned according to their grade.
2 Definition
For the purposes of this part of ISO 8512, the following definition applies.
deviation from flatness of the working surface:
The minimum distance separating two parallel planes between which the working surface can just be contained.
3 Nomenclature
For the purposes of this part of ISO 8512, the nomenclature shown in figure 1 applies.
4 Material
Surface plates complying with this part of ISO 8512 shall be made from stable, workable rock presenting a wear-resistant surface which does not tend to scratch steel surfaces. Igneous rocks such as diabase, gabbro and various other granites have been found suitable; they are commonly referred to as “granite” for the purposes of this part of ISO 8512.
Rock used for surface grained and of uniform from flaws and fissures softer materials. Repair surface is not permitted.
plates shall be close texture, sound and free and from inclusions of of defects in the top
The colour of the granite, which is dependent on the mineral composition, is of no importance, but the colour of any individual plate shall be uniform.
NOTE 2 Some of the physical properties of granite used for surface plates are given in annex E.
5 Preferred sizes
The preferred sizes for granite plates are given in table 1. If plates of other sizes are required, the requirements of this part of ISO 8512 shall nevertheless apply.
The lengths of faces of plates shall be within ± 5 % of the nominal size.
NOTE 3 It will be seen that the nominal lengths of faces, with one exception, are taken from the R5 series of preferred numbers; one plate, size 2000 mm x 1000 mm, is included because it is an established and widely used size, although 2000 is not an R5 preferred number.