Road to Sharpness
Manufacturing Process of Knives
The typical manufacturing process will be introduced with videos.
Quenching
Blade blanks are heated to a high temperature of 1,050℃ or above in an electric furnace to be hardened. The hardness will be improved by quenching the heated blade. Afterwards, to stabilize its structure and improve wear resistance, it will be tempered to 200℃.
Bolster Polishing
The bolster attaches the blade with the handle and prevents dirt from building up, improving its hygiene. The welded blade and the burnt bolster are polished by hand. The handle will be easier to grip once the joints become smooth.
Wet Grinding
The thickness of the blade is reduced by grinding with a coarse grindstone. This will give the knife a lighter cutting motion. In addition, the finishing sharpening will give the blades a mirror-finish, which reduces the resistance between the blade edge and food. Since the hard material is finished with a fine grindstone, it is difficult to determine the amount of pressure that needs to be applied on the blade, making it a process that requires the skill of craftsmen.
Buffing
Once the blades are sharpened, they will be left with a “burr”, which is a thin layer of ragged metal raised on the edge. Placing the burred edge on a leather buffing wheel will chip it away and give a smooth edge.
Sharpness Inspection
The sharpness of the knife will be quantified to manage its quality. A constant load is applied on the knife to slice through a stack of paper. The number of sheets that were cut will be compared with the reference value to check the condition of the blade edge.
Forging
Process of shaping blades for traditional Japanese knives. The ancient Japanese technique of swordsmithing that has been passed on to our generation. Steel is heated and hammered to make a long blade. The metal structure is refined by hammering, which creates a harder blade.
