- Laser cutting
- Thermal process
- Periphery polishing / Surface grinding
- Blade leveling / grazing
- Bolster welding
- Mirror polishing / Abrasive blasting
- Wood handle polishing / bolster polishing
- Printing / marking
- Wet type blade edging
- Inspection / Packaging
Laser beam is directed at the material, stainless steel, and cuts out the shape of knife blade from it. The laser cutting process is controlled by computer and also finely structured designs can be cut out by this process. This process requires more time than press working process using molds, but it is widely utilized in the production of articles of elaborate design, in small-lot production and in trial production.
The laser cut knife blade is heated at 1,000℃ in an electric furnace and then it is cooled off at water temperature. With this process, the structure of the stainless steel material changes and the blade becomes hard. After being cooled, the blade is heated again at 180℃. In this way, a blade that is not only hard and tough but also elastic, is obtained.
Periphery polishing / Surface grinding
After the thermal process, the periphery of the blade is polished with polishing belt. A computer-controlled machine adjusts the shape of the knife with whetstone. Subsequently, the surface of the blade tip is thinly grinded in the surface grinding process. This surface grinding process and the following polishing process are important processes that allow to obtain the beautiful pattern on the blade that characterizes Damascus kitchen knives.
Blade leveling / grazing
The blade leveling process consists in polishing the blade tip with a particular polishing material, making it take the shape of a smooth hard clam. Then, the entire blade is more finely polished in the grazing process and a blade entirely polished and with a perfect surface is obtained.
Bolster is welded to the blade. The bolster is a part of the handle that reinforces the junction between the blade and the handle. By welding and fixing the bolster to the handle, it becomes difficult for water to penetrate into the handle and the handle's durability increases.
The "Damascus steel pattern", resembling the patterns on the edge of Japanese swords
Some of KAI's kitchen knives have a beautiful pattern, similar to those of Japanese swords, engraved on the blade. This pattern is called "Damascus steel pattern" and it is drawn utilizing a particular kind of steel material obtained by depositing many alternating layers of hard steel and soft steel. During the press work, these layers are disturbed by the pattern embossing process and by scraping this material with disturbed layers, it is possible to obtain this particular pattern.
Mirror polishing / Abrasive blasting
In order to obtain a finish finer than that obtained by the grazing process, the blade is inserted between two rolls and is polished until it reflects images like a mirror. Then, the blade is submitted to the abrasive blasting process, that consists in spraying glass beads (fine glass particles) on it. Thanks to this process, the difference of surface's roughness of soft parts and hard parts of the stainless steel material is evidenced and unique stratiform patterns appear on the blade. These patterns are the designs that characterize Damascus kitchen knives.
Nail clipper for ingrown nails, satisfying a wide range of customer demands
Nail clippers with normal shaped blades do not fit to ingrown nails and if you try to clip them forcibly from the sides, the nails may crack. The convex blades nail clipper was originally developed in order to solve this problem. The blades were improved and were given a convex shape that fits to ingrown nails, making it possible to clip them easily. In particular, "Square-cut" is a product that allows clipping the center of the ingrow nail with the convex blades and then cutting the nail straight across with the straight blades.
In the assembling process handle and rear bolster are fitted to the blade. Excellently water-resistant reinforced laminated wood is used as material for the handles. When fitting the handle, measures to enhance waterproofing property, such as using sealing material to prevent the penetration of water, are taken. Parts produced with MIM technology are used as bolster and rear bolster of some high-class kitchen knives.
Wood handle polishing / bolster polishing
This process consists in polishing the handle of assembled knives, the bolsters and the rear bolsters. By polishing the level differences of the small parts and their surface, it is possible to obtain a beautiful, smooth handle. Utilized polishing agents vary according to the part and each part is polished by expert craftsmen.
Printing / marking
Each kitchen knife has a mark printed on it. The mark indicates the brand name and the lot number that enables to identify its manufacturing date. This system allows the achievement of traceability, making it possible to identify the history of utilized materials, the date and time when each process was carried out and the workmen that carried out the processes.
Wet type blade edging
This method of blade edging is utilized for the high class lineup. By doing the grinding pouring water on the whetstone, it is possible to avoid the production of friction heat and to increase greatly the smoothness and the cutting quality of blade tips. The workmen that are able to carry out the wet type blade edging are very few. Only workmen with many years of experience are allowed to carry out this important process.
Inspection / Packaging
Last of all, burrs (ragged edges formed during grinding) are removed using tanned leather and after this process, the kitchen knife can be considered completely completed. Then, cutting quality of knives' blade is checked one by one. In order to make sharpness in cutting and durability compatible, blades should have a specific blade angle. The blade angles of knives are strictly inspected and controlled with measuring instruments. Then, completed knives are carefully packed in boxes.
The 3 types of "blade edging" methods, breathing life into kitchen knives
There are 3 methods of edging the blades of kitchen knives. The first one is the wet method: it utilizes a doused whetstone rotating horizontally and it is applied to high class products. It is a very difficult process, so, only few workers in the company are able to carry out it. The second one is the dry method. In this method, the blades are edged using a vertically rotating whetstone and this process is applied to products for wide distribution. Here, it is also adopted a third method, the blade edging using robots. The movements of the robots grinding blades on whetstones favorably compare with the movements of workers.