
Thermal Diffusion Process, Toyota Diffusion process
Strengthening Metal to Its Core
A new standard of durability achieved through the TD process
TD Process is a thermochemical surface coating treatment technology that diffuses vanadium (V) atoms onto a metal surface at high temperatures (1000℃) to combine with carbon in the base material, forming a very hard and chemically stable carbide (VC) layer. This technology creates a carbide (VC) layer through diffusion, superior to general coatings or surface hardening treatments, ensuring excellent durability even under extreme wear conditions.
SP HEAT TREATMENT utilizes high-temperature diffusion reactors to provide TD treatment for cold working molds, trimming dies, punches, cold forging molds, and more. The TD layer typically reaches a hardness of HV 3000 ~ 3800. Since the film does not peel off and is integrated with the metal structure, there is almost no performance degradation even after long-term repeated use. Furthermore, it has a low friction coefficient, excellent heat resistance (Max 550℃), oxidation resistance, and wear resistance, maintaining stable performance in various demanding work environments.
Our TD Process is systematically managed from basic pre-treatment to the reaction process and post-treatment, allowing for the design of process conditions tailored to the material, shape, and application of the customer's product. It exhibits superior performance in hardness, wear resistance, and anti-seizing properties of the diffusion-formed coating layer (VC) compared to conventional nitriding and carburizing treatments.
Especially under extreme operating conditions such as repetitive molding processes, high-speed punching, and forming of high-strength steel/ultra-high-strength steel, the superiority of the TD layer directly leads to improved productivity and reduced maintenance costs. SP HEAT TREATMENT provides the best technical solutions through the TD Process for industrial sites requiring precision and durability.
Applications

Trimming Dies, Press Molds, Punches

Cold Forging Molds and High-Load (High-Strength Steel) Forming Molds

High-Speed/High-Repetition Impact Parts

Metal Parts where Wear Resistance is Paramount
(When HV3000 or higher is required)