An aluminum alloy plate is used for a disc used in the external memory media for a computer. Due to its applications, the disc must have a precise quality in terms of flatness and surface defect-freeness. Aluminum, which is likely to warp, is maintained at a flatness of 5 micron or less. Thus, Furukawa Electric uses aluminum of purity 99.96% and a complete management system to mass-produce disc materials. The mass-production is so strict that one-third of the manufacturing process consists of inspection steps. Furukawa Electric, which has about half the world's share in memory discs for desk-top personal computers, maintains an overwhelming superiority to the other companies. It ranked No. 1 in the world largest HDD company's "Quality Competition Among All Suppliers" for 24 consecutive months, and is continually setting a new records.