Specifications

100% Japanese-made
Produced at our own factory
With cutting-edge cold forging technology
Smooth & Beautiful finish

Japanese hand tool Impact extension bar with ratchet handle

 

Socket wrenches from Koken. Sockets are 100% Japanese-made.
Produced at our own factory.
We utilize cutting-edge cold forging technology.
You’ll marvel at the smooth, beautiful finish
and the even metal texture, all produced with razor-sharp precision.

 

High-quality, 100% Japanese-made sockets, socket wrenches, and extension bars.
We polish our products with machines and by hand.

 

Ko-ken’s socket wrenches are manufactured at our own factory to the highest standards of quality. Our socket wrenches are made extremely tough and durable through heat-treating, and our highly precise cold-forging technology allows for a smooth flow in the metallographic structure. The beautiful, smooth uniformity of the metal surface conveys the true expertise embodied in Ko-ken’s cold forging technology.

Ko-ken’s socket wrenches are produced using state-of-the-art metal cutting machinery. Unfinished sockets are created from simple steel cylinders, with interiors crafted via a high-density, high-precision manufacturing process. They are cut with a highly precise lathe. The handle and exterior are fitted to a square-opening bowl to create the finished product.
Ko-ken’s sockets are manufactured at our own factory, with strict quality standards that limit dimensional tolerances. Our sockets are strong because of their smaller deviation between the hexagonal opening and the circumference.

Ko-ken’s socket wrenches are 100% Japanese-made, as indicated by the words “MADE IN JAPAN” engraved on each wrench’s surface. Additionally, impact sockets sizes can be readily identified thanks to their white lettering. We were among the first in the industry to adopt this lettering method over fifteen years ago.

Ko-ken’s socket wrenches are heat-treated using our factory’s special heat-treatment equipment that features extremely precise temperature controls. This highly refined process determines the durability of our socket wrenches that balances firmness with flexibility. Through precise regulation of the temperature and heating duration, we can control both the tempering process, which adds firmness, and the annealing process, which adds flexibility, resulting in optimal heat treatment for each product.

Ko-ken’s socket wrenches are polished with machines and also by hand. Each wrench is coated with a lacquer that provides grip and a mirror-finished surface.
The products are put into oscillating barrel with an abrading agent for full-surface polishing. We also utilize center-less machine polishing, in which the products are rolled between two grinding stones rotating at high speeds. Finally, our polishing workers buff each product individually to ensure quality. Our combination of machine and hand work guarantees a good job.

Our socket wrenches feature a uniform interior, as well as a beautiful, durable exterior achieved through surface finishing. The final step in the manufacturing process, surface finishing, ensures not only a beautiful exterior, but also longevity, durability, and adhesion to prevent peeling despite high-intensity usage. Our Quality Control department regularly monitors the quality of our surface finishing process by measuring the thickness of the plating, conducting salt spray tests to confirm anti-rust properties, and performing destructive tests to ensure resistance to peeling.

 

 

For over a century, our firm has specialized in offering products to support Japan’s manufacturing industry. We strive to create stable, long-term business partnerships based on the extensive knowledge, service, and trust we have cultivated over the hundred years of our history.
With this foundation of trust, we are able to take in stock from over 1000 domestic manufacturers and can supply any and all Japanese-made parts. Raise the value of your company’s products with trusted Japanese parts and consider making us your partner in your ongoing development.