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Dr. Toru Arai - The Inventor or the TRD Process

After graduating with a master’s degree in metallurgy from a university, he served at the Technical Research Center of Nachi-Fujikoshi (the world’s largest maker of high speed steel cutting tools and ball bearings ECT.) for 7 years as a research engineer and a manager of material division. Developed high performance tools and wear resistant parts that consisted of tool steels with a large amount of fine carbide grains made by special processes including surface treating methods. Recognized, through their application outside and within Nachi-Fujikoshi, high performance production tooling could provide a tremendously large profit to industries.

Left: President/CEO Teikuro Corporation, Toyohiko Ichikawa
Right: Techinical Director, Teikuro Corporation/TRD, Dr. Toru Arai

In 1965 he then moved to Toyota Central research and Development Labs. Inc. (TCRDL) and continued to research works for development of wear resistant materials as well as heat treatment. He also received a doctorate degree through his research on the tool steels quenched from a liquid state made by localized re-melting with high energy heating systems and built up welding. In 1968 he developed a carbide coating process that can completely cover the surface of a substrate with carbide by a salt bath immersion method. This process is called “Toyota Diffusion” (TD) in Japan, “Thermal Diffusion” (TD) in the USA and finally referred to as “Thermo-Reactive Deposition and Diffusion” (TRD) including other processes by fluidized bed and powder packing. This process has been in use for practical application since 1969 in Toyota group companies and is being used more or less in almost all fields of industries. This salt bath method has been licensed to be used in about 10 companies located in Japan, Europe, Australia, Asia, and South Africa.

Evaluation of some properties was difficult because there were no adequate methods of testing the properties of such a newly developed material. For example, tribological property of a die and mold can not be measured by the conventional wear tests. Special methods needed to be developed that would more closely simulate the actual working condition of a die and mold. Fortunately Japan is a world leader in this field and a number of evaluation methods have been proposed by researchers belonging to a group called “Process Tribologist”. An evaluation of tribological properties of TD coated materials was made using these simulating methods comparing it with other surface modification processes.

Results of practical application of the TRD process came into TCRDL directly from Toyota group companies and from the other licensed users of the TRD process. They are accumulated as important information or application experiences although there is some differences in usefulness. After he retired as a director of TCRDL he immediately joined Arvin TD Center in 1994 as a technical advisor. He now works more closely to the particle application in the USA. Being deeply involved in R&D and application works of wear resistant materials and surface treated materials for a long time made Tohru Arai different from other researchers and engineers in this field of surface modification.

He has published more than 150 papers in Japanese and 40 papers in English dealing with TRD, PCVD, Other surface treatments, tool steels, heat treatment, evaluation of properties, and application.

He worked as a guest professor and lecturer in four national universities in Japan from 1988-1994.

Received honors and awards from Japanese government and professional institutes in Japan as well as 1976 IR-1000 Winners (USA)