Checks/tests of dimensions, straightness and surface hardness are always performed by qualified testers using calibrated equipment. Hardness testing equipment is calibrated according to ISO 6506-2. Brinell hardness test HBW according to EN ISO 6506-1 using a polished 10 mm hard metal ball forced into the surface 0.5 – 1 mm below the surface of the sheet metal. The frequency of checks varies depending on product type from one sample per furnace batch to all steel.
Product tolerances are according to ISO 2768 if circumstances not require special tolerances. Generally, contours of the product are according to ISO 2768 v, hole c/c according to ISO 2768 m. Generally, max. 2.0 mm/m for edge straightness. Can be specially ordered with a tolerance as low as 0.3 mm/m for edge straightness. For raw materials tolerances are according to EN 10029, EN 10060, EN 10058, and EN 10092-1.
Product tolerances for surface finish are according to EN 10163, unless otherwise specified at time of order.