Granite surface plate

These plates are a benchmark surface, built to guarantee extreme planarity – that is, to present a completely flat and smooth surface. Such certainty is the basis of the precision of any measurement taken upon it; and since this perfect planarity must persist over time, two factors must coexist. One is the utmost attention during manufacture; the other is the choice of a material capable of guaranteeing lasting stability over time. Preferred materials must thus boast remarkable resistance to deformation by temperature as well as high sturdiness. A perfectly flat surface guarantees accurate and precise measurements; plates can be used as an accessory in measuring machines which range from a few square centimetres to several square meters. The preferred materials, both for ease of working and resistance, are cast-iron and black granite. F.lli rotondi’s cast-iron plates are made of G 26 UNI 668 grey cast-iron with a hardness of 200 ÷ 220 HB and a pearlitic structure, which make it highly wear-resistant. Absolute black granite plates manufactured by F.lli Rotondi have perfectly polished and honed surfaces, with a hardness of about 90 Shore, and boast the highest stability and rust imperviousness. While both kinds of plates offer high quality control, granite plates – while more complicated to manufacture – present several advantages over those made of cast-iron. Granite boasts a far higher stability over time, and is completely immune to rust; furthermore, it has definitely higher resistance to any kind of temperature-induced deformation, so much so as to make temperature completely irrelevant.