Tellurium Copper for Free Machining

Luvata has been the world’s biggest supplier of copper tellurium (CuTe) rods and bars for the last 20 years. Our quality has been the highest in the industry and we are continuously developing our processes and process parameters to sustain the leadership, which enables our customers to improve their processes and develop their business in higher added value products.

Applications

A big portion of tellurium copper is used for manufacturing of gas cutting nozzles, which involves the drilling of small holes and swaging to the final shape. For this application we produce tellurium copper rods of various hardness to suit the customers’ individual manufacturing processes. The high electrical and thermal conductivity of tellurium copper makes it suitable for electrical applications.

As a free machining copper tellurium copper is a superior alloy in all applications where products are drilled, turned or machined in some way. Both manual and automatic product lines’ efficiency is several times higher than in the case of traditional pure copper, which is a very ductile metal. For example, the cutting properties of copper can be significantly improved by alloying copper with half a percent of tellurium. The electrical and thermal conductivity and ductility of this free machining copper are only slightly altered. Copper telluride precipitations in the microstructure break up the turnings into chips thus enabling a much higher machining speed than is possible with pure copper. On a machinability rating scale with 100 being for free cutting brass and 20 for copper, tellurium copper is rated at 90.

Manufacturing

Luvata’s production starts from high quality Grade A cathodes, which are melted and cast into billets. It is essential that all free oxygen becomes eliminated from copper by adding phosphorus because oxygen could bind tellurium into an ineffective oxide and it could also make the copper brittle.

Another important characteristic is the distribution of copper telluride particles. For maximum effect these particles should be small in size and evenly distributed over the whole cross section of the product. We have developed our billet casting process to produce fine and evenly distributed precipitations.