• Rasha Machinery Private Limited

Surface Plates

Rasha Machinery offers surface plates made of close grained castiron. These are amply ribbed to minimise deflection under load.The composition of the metal, the depth and cross-section of the ribs and the thickness of the plate are designed to conform tothe deflection limits specified in IS 2285-1963. These surface plates are manufactured to two tolerance standards--Grade-I and Grade-II. Grade-I plates are more precise than Grade-II plates. The deviation in flatness for Grade-I and Grade-II plates for sizes up to and including 2,000 x 1,000 mm are as prescribed in IS 2285-1963. Grade-I plates are artificially seasoned. They are hand scraped to achieve maximum local deviation from flatness of 5 microns over any length of 300 mm at any point on the working face, in plates of 630 x 400 mm and larger. A special scraping technique is used to achieve a uniform distribution of load bearing points and oil pockets. An average of 15-20 load bearing points, after finish scraping, is standard. This finish scraping technique ensures that the area of the load bearing points increases after the initial dulling of the high points. This guarantees a long working life, at the required accuracies. Grade-II plates are accurately machined to get the requisite flatness. Standard accessories include handle and wooden cover. Optional accessories include fabricated mild steel stands with three levelling screws; cast iron column floor stands; a set of five, three for levelling and two for support for 2,000 x 1,000 mm plate; and a set of seven, five for levelling and two for support, for 3,000 x 1,000 mm plate.