We have long been engaged in the development of surface treatment technology (metal coating) to improve the abrasion resistance of engine chain pins, which are used in harsh operating environments.

Our original patented product, a car engine chain coated with VCN (vanadium carbonitride), has a higher abrasion resistance than conventional products, thus prolonging life and downsizing and reducing the weight of the chain.

We are proactively applying our chain manufacturing technology and knowhow to other products with the aim to create added value such as improved abrasion resistance and the reduction of surface damage.

Patent No. 5608280: Chain bearings and their manufacturing methods, and chains using these bearings

Our surface treatment (metal coating)


Cementation is a heat treatment method used to improve metal surface condition by diffusing metal or nonmetal powder onto the metal surface. Various properties can be added to the metal, depending on the element diffused.

Using the powder packing method, chrome (chromizing) or vanadium (vanadizing) is diffused onto parts such as engine chains, which are used in extremely harsh abrasive environments. This produces a hard coating on the metal surface, remarkably improving abrasion resistance.

Powder packing method


Surface hardness/ Abrasion resistance

Our chrome carbide (CrC) and vanadium carbide (VC) coatings attain hardnesses of Hv1400 and Hv2000 respectively, which are higher than those attained by ordinary hard surface treatments such as carburizing and nitriding.

When the coating is applied to car engine chains, which bend repeatedly under a high tension of 2000N or more (similar to the tension applied when a sumo wrestler weighing 200kg hangs), the amount of chain abrasion is only 10 microns (1/100 of 1mm) even after the car has travelled 200,000km.

Coating thickness/ Adhesiveness

The coating thickness can be adjusted from a few microns to over 10 microns, making flexible application possible. Examples include applying a thin layer to precision components that require strict precision, or applying a thick layer to machine components that bear high load and require high abrasion resistance.

Due to its high adhesiveness, the coating does not peel off and its abrasion resistance is maintained even when applied to components that are used in a harsh sliding environments (high load), such as car timing chains and variable valve timing mechanisms (VTC).


Batch coating is conducted using the powder packing method in our specialized furnaces. A large number of parts can be processed uniformly, at the same time.

Coating types/ Features

Name of our original coating SDH SV
Surface treatment Chrome carbide (CrC) coating Vanadium carbide (VC) coating
Surface hardness(hardened layer thickness) 1,400Hv or more
(a few microns to 10 microns or more)
2,000Hv or more
(a few microns to 10 microns or more)
Features Abrasion is minimized by a hard CrC layer

・Excellent abrasion resistance, corrosion resistance and heat resistance
Abrasion is minimized by a hard ceramic layer

・Higher abrasion resistance than SDH
Coating layer image

Application examples

Engine chain parts

  • Part: Chain pin
  • Coating type: SDH, SV

Variable valve timing mechanism (VTC) parts

  • Part: Lock pin, sleeve
  • Coating type: SDH

Basic research (tribology research)

Tribology refers to science and technology involving all phenomena occurring between two surfaces that influence each other in relative motion, including lubrication, friction, abrasion, seizure and bearing design.

Our surface treatment featuring high abrasion resistance is based on technological findings obtained from our long-term tribology research to clarify friction and abrasion mechanisms. To further improve our technology, we are studying the conditions of friction, lubrication and abrasion using various test machines, and accumulating technologies and knowhow to produce better sliding surfaces.

Ball-on-disc/ Pin-on-disc test machines
Function test using a friction test machine

Papers that we have contributed to (selection)

  • 2013: Tribology Conference: The Ceramic Coating Abrasion Mechanism in Soot-contaminated Lubrication Oil
  • 2014: Car Technology Academic Conference: Development of an Anti-abrasion Surface Treatment for Engine Chains
  • 2017: Tribology Journal 2017 Dec. edition: Trends in Engine Chain System Technology