Hexagon nuts ~0,8d ISO 4032-copper CuNiSi M12

The wrench sizes for hexagon bolts and nuts are specified in ISO 272: 1982-01. The nominal wrench size on the workpiece (e.g. bolt, nut) is the same as that on the tool. However, there is some play between the two to allow the tool to be fitted without difficulty. The relationship between the nominal diameter d of the thread and the wrench size s is standardised in EN ISO 4014 and EN ISO 4017 for hexagon bolts, and in EN ISO 4032 for hexagon nuts (dimensions in mm).

Copper is a chemical element with the element symbol Cu. As a relatively soft metal, copper is easy to mould and tough. It has many uses as an excellent conductor of heat and electricity. It also belongs to the group of coinage metals. As an important technology and functional metal, copper is a semi-precious metal. Copper-tin alloys are known as bronze, copper-zinc alloys as brass.

The term plain indicates a completely untreated, merely oiled, smooth surface for all DIN and ISO screws such as wood screws, hexagon head screws, threaded rods, nuts and many types of washers.

CuNiSi is a precipitation-hardened copper alloy. It combines medium electrical conductivity (min. 47% IACS) with high strength and good relaxation behavior. This is achieved through a process route involving cold forming and heat treatment. Furthermore, the alloy has excellent spring properties and good corrosion resistance.