Since our foundation, we have developed our fields of manufacturing from chains and motorcycle rims and wheels to car components, industrial machines and welfare equipment.

Through our search for highly functional and quality products, we have acquired various manufacturing skills in metal forming, welding and grinding as well as heat treatment and surface treatment for enhancing products’ strength, corrosion resistance and abrasion resistance.

We have an integrated manufacturing system to manufacture products with the required functions and qualities by combining various skills according to customers’ needs.

Technologies used in our products

Product Material Forming Welding Grinding Heat treatment Surface treatment

Cars/ Motorcycles/ Industrial machine chains

Special steel
Press formingMachining
ForgingIn-house die
Arc welding
Barrel grinding
Shot blast
Carburizing and quenching

Iron rims
Agricultural machine wheels

Iron Roll forming
In-house die
Arc/ Spot welding
Flash butt welding
Buffing   Plating

Aluminum rims

Aluminum Roll forming
In-house die
Flash butt welding Buffing Solution treatment Artificial aging Alumite

Handle pipes

Aluminum SwagingBending
In-house die
  Shot blast Solution treatment Artificial aging Alumite

Plastic forming products
Cut products
Resin molding products

Press formingMachining
ForgingInjection molding
In-house die
  Barrel grinding
Shot blast
Carburizing and quenching


Pressing/ Bending/ Roll forming

Special use dies are used to shear or bend products with a large force and form them into the required shapes using press machines or forming machines.

Although these are basic metal forming methods, high-precision presses, forming machines and dies as well as the relevant knowhow are required to attain high processing accuracy.
We manufacture many dies ourselves to realize high accuracy in forming chain parts and motorcycle rims and handle pipes.

Advanced plastic forming

Our chain manufacturing skills have been developed into “SOSEI-FORMA technology”. It enables 3D forming and precision shearing, which were difficult using conventional pressing. Please see the Plastic forming technology page for details.

Forging (cold forging)

A horizontal multi-step forging machine is used to cut materials into the desired lengths, put them in molds and press and form them into the desired shapes.

Punching, blanking and extruding are possible, according to the application. Materials are pressed and formed without cutting processes; therefore, compared to cutting, forming can be done in less time with less material loss and cost. This method is used to manufacture our chain parts.

Roll forming

Multiple roller dies are used to gradually form material surfaces according to the roller shape.

Steel material in the shape of a belt or cylinder is formed according to the die shape. It is possible to process thin or hollow materials and complex shapes. This method is used for our iron motorcycle rims and agriculture machine wheels.


Segmented dies are rotated to hit metal pipes, decreasing their diameter.

Pipes with circular, square or divided rectangular cross-sections can be tapered without cutting or welding to improve their strength or bend them moderately. This method is used for our motorcycle handle pipes.

Machining (cutting)

Materials are formed with machining tools or cutting tools.

This method is used for products that require strict dimensional accuracy when it is difficult to manufacture via plastic forming such as pressing. However, it is inferior to plastic forming in terms of productivity and cost. Thus, this method is used only when it is difficult to manufacture products via plastic forming. We use this method to make pressing dies for manufacturing chain parts.

Injection molding

Synthetic resin is heated and melted and then put into metal dies to be formed.

This method enables the fast, continuous production of a large number of products in various complex shapes; therefore, it is appropriate for the mass production of resin products. It is used in the production of the resin parts of our car engine chain systems.

Welding/ Grinding

Flash butt welding

This is a type of butt welding. Two pieces of metal are placed end-to-end without overlap and an electric current is applied to produce sparks and melt the contact surfaces. After the metal surfaces are heated sufficiently, a high load is applied to joint them.

This welding method is speedy, highly efficient and reliable in producing high contact strength. It has a narrow heating range and a small heat-affected area. This method is used for welding our aluminum and iron motorcycle rim cross-sections.

Arc/ Spot welding

Arc welding (MIG/ TIG) uses discharge phenomena in the air in order to joint metals. Spot welding uses an electric current to melt and joint metals using resistance heat.

Spot welding in particular requires only a small welding area, so its finished surface is cleaner than those produced via other methods. This method is used for welding our agricultural machine wheels.

Barrel grinding/ Buffing

In barrel grinding, grinding stones, compound and water are put in barrels and they are rotated or vibrated to grind products. In buffing, sheets of cotton, linen or paper applied with polishing paste are rotated to polish products.

We use this method to remove burrs from chain parts, improve surface roughness and finish aluminum and iron motorcycle rims.

Shot blast

Projectiles (fine sand, iron or stainless particles) are sprayed or shot onto product surfaces to make them rough.

This method produces rough surfaces, so it is possible to produce an appearance different from that produced by barrel grinding or buffing. We use this method for finishing motorcycle handle pipes, chains, plastic forming and cutting products.

Heat treatment

Carburizing, quenching and tempering

Metal surfaces containing little carbon are cemented with carbon to increase the carbon rate near the surface. Then, the metal is quenched or tempered to create a hard layer on the surface.

Treated material becomes hard on the surface and remains soft in the core, so it obtains both high strength and high abrasion resistance. This method is used in various industrial fields. It is used for our chains and engine parts that require high strength and high abrasion resistance.


Metal surfaces are cemented with carbon and nitrogen at the same time to create a hard layer. NH3 gas is added to common cementation gas and the material is cemented and nitrided at the same time with nitrogen decomposed from NH3.

The treatment temperature is lower than carburizing; therefore, it causes less material deformation. Also, compared with carburization, a hardened layer created by carbonitriding is thicker and more abrasion resistant even when it is conducted at the same temperature for the same treatment time.


This is a quenching method conducted at a constant temperature to obtain bainite structure. Compared with structures created by ordinary quenching or tempering, bainite structure has improved ductility and impact resistance as well as a higher toughness and durability.

Austempering has some advantages compared with ordinary quenching or tempering. It improves material toughness and durability and causes less deformation after quenching. This method is used for our car engine chains, which require high durability.

Solution treatment/ Artificial aging

These are a set of heat treatment processes to improve aluminum alloy strength. In solution treatment, the aluminum alloy is heated to uniformly dissolve undissolved elements within the alloy. Then, in artificial aging, the alloy is heated again to precipitate the elements and enhance hardness.

Through these processes, light, strong aluminum products can be produced. These processes are used in the production of our aluminum motorcycle rims and handle pipes.

Surface treatment

Cementation (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.

Please see the Surface treatment technology page for details.

Alumiting (anodization)

Aluminum products are put in electrolyte and electric current is applied to produce an oxide film (aluminum anodized film) on the surface via electrolyzation.

The created film is hard and highly corrosion-resistant. It can also be dyed any color; therefore, it is used in the protection of aluminum products and decorations. We use this method to improve the corrosion resistance of aluminum motorcycle rims and handle pipes and color them.


A thin metal layer is formed on the material surface. This process is used to decorate products or make them corrosion resistant.

There are two types of plating methods: electrolytic plating and non-electrolytic plating. There are also some variations such as nickel plating and chrome plating, selected according to the material used. The appropriate method and plating material are selected depending on the application. We use this process for the production of gold chains and iron motorcycle rims.