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Release: March 12, 1996

NGK INTRODUCED OUTER DIAMETER OF 300 MM SILICON NITRIDE ROLLERS TO SEAMLESS PIPE ROLLING PROCESS

NGK Insulators Ltd. (President: Masaharu Shibata, Head Office: Nagoya) developed outer diameter of 300 mm fine ceramic carrier rollers, which are used for the mandrel mills in the process of seamless pipe rolling.

The newly developed roller, which is made of silicon nitride ceramics , is one of the world's largest constructional materials.

The carrier rollers have been made of cast iron or super hardened metal; therefore, in the process of carrying the rolled-material under the high temperature from 800 centigrade to 1000 centigrade, the cracks and the burn marks have appeared on the rollers' surface. As a result, the surface of the rolled-material have been damaged. Especially the rolled-material such as stainless-steel, which does not have any rust like substance between the rollers and the stainless-steel itself, easily scorches and sticks directly to the carrier rollers. Therefore, the manufacturers have been required to stop operating the mills in order to polish and treat the surface of rolled-material, which results in the significant lowering of productivity.

NGK, by replacing the strongly damaged rollers by the silicon nitride ones with metal junctions, has produced approximately 300 thousand pipes for five months without stopping the mills' operation. Through the whole period, NGK has not recognized any damage on the rollers' surface, and also no polishing and treatment have been required. NGK's introduction of silicon nitride ceramics carrier rollers with metal junctions contribute to improve the productivity of seamless pipes, especially made of rolled-stainless-steel, and to prevent the defective products.

NGK is planning to actively enlarge the market of its newly developed rollers.


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