Press brake bending copper, bronze, and brass

The oldest metal in history has always new usages

At an annual consumption exceeding 18 million tons, copper and its alloys are among the most used materials in industry, in spite of its high cost. Its versatility, its electrical and chemical properties, and its appearance make it irreplaceable. The main users of about 370 copper alloys are construction (roofs, gutters, piping, electrical wiring), electronic industry, transport, and machine tools.

To eliminate the oxide or the rolling scale, we can use a very fine abrasive, possibly followed by a pickling bath. To preserve the typical reddish color, a clear coat is applied. Like stainless steel, copper also forms a surface oxide coating that protects it from corrosion, especially when it is alloyed with the aluminum.

Copper must be handled carefully, avoiding steping on it or denting it. The surface should remain wrapped in the protective adhesive film, and sheets should be kept separate with paper, wood or other material to prevent scratches. Copper can be cleaned with warm water and soap. Specific chemical detergents are available for industrial use. During shearing and bending, we can follow the same techniques used to protect stainless steel.

Common cutting processes for copper alloy sheets are:

• Shearing/guillotining• Laser cutting• Plasma cutting• Longitudinal and transverse slitting• Waterjet cutting• Abrasive disc cutting• Electrical discharge machining

Pure copper is ductile, with a yield strength of about 70 MPa. Shearing requires less tonnage with respect to steel, but special attention must be paid. Because of high surface reflectivity, CO2 laser cutting may be difficult.

Copper sheets can be formed with all fabrication techniques available. Its ductility allows for deformations greater than other materials. Minimum bending radius is roughly equal to thickness. Machinery and tools used for copper alloys should not be used with other metals to avoid corrosion.

Main copper alloys are bronze and brass. Originally, bronze was defined as the alloy of copper and tin. Nowadays, it also includes alloys of copper and other elements, except nickel and zinc.

The main types are:

• Classic Bronzes: copper and tin• Phosphorous Bronzes: copper, tin and phosphorus• Lead Bronzes: copper, tin, lead and phosphorus• Aluminum Bronzes (Aluminium Bronze): copper, aluminum, iron• Aluminum-Silicon Bronzes: copper, aluminum, nickel, iron, silicon, and tin• Silicon Bronzes: copper, silicon and tin (Sn-Cu-Si)• Nickel and tin Bronzes: copper, nickel, tin, zinc, lead• Manganese Bronzes, Manganese and Lead Bronzes: copper, zinc, manganese, iron, lead• Tin Bronzes, Tin and Lead bronzes: copper, tin, zinc (and lead).

Original brass is an alloy of copper and zinc, less hard than bronze but more resistant to corrosion. Brass alloys make up the largest product volume of copper alloys.

The main types are:

• Classic Brass: copper and zinc• Lead Brass: copper, zinc, and lead• Tin Brass: copper, zinc and tin• Manganese Brass (also called Manganese Bronze): copper, zinc, manganese• Manganese and Lead Brass (also called Manganese and Lead Bronze): copper, zinc, manganese, lead• Silicon Brass: copper, zinc, silicon• Aluminum Brass: copper, zinc, aluminum

Cupronickel is the alloy of copper and nickel, with a remarkable resistance to seawater corrosion. It can also be used with addition of other elements such as iron, manganese and tin. It is the metal used to mint the clear part of 1- and 2-Euro coins.

Copper alloys are joined together primarily by brazing, although all the main welding techniques can be used. In case of riveted or bolted elements, one must use rivets and screws of the same material to avoid galvanic corrosion.

Tree of brass, bronze, and other main copper alloys

Gasparini Industries s.r.l.

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