Japan’s Only Diamond Screens and Slotted Grills
In 1960, Nunobiki Manufacturing received a section of a used imported screen of a shape unfamiliar to the staff. It was a mystery as to how it was made, but the staff took up the challenge, scrutinizing the segment from all angles. Different materials were used, and the dies were repeatedly modified. After 10 years of much trial and error, they succeeded in producing an identical diamond screen.
Diamond screens are mainly used in centrifuges and sorting machines for salt manufacturing, and grinders. The fine holes, shaped like triangular pyramids, are given direction and can be made to a minimum size of 0.05mm. The screens must have very high precision, so it is essential they are regularly examined using strong magnifying glasses and microscopes. It is yet to be proven whether the methods Nunobiki Manufacturing developed to produce these perforated screens are the same as those used by the German manufacturer, whose name was discovered later, of the original fragment. The diamond screen was released as a Nunobiki Manufacturing-unique product original to Japan, and the manufacturing method was patented. Nunobiki Manufacturing went on to sell this product to seven salt manufacturers.
The client that the brought the used segment approached Nunobiki Manufacturing around the same time to ask about the feasibility of producing a screen similar to another segment that had horizontal, directional, rectangular-shaped, long holes, instead of triangular pyramid-shaped holes. This screen was also used in centrifuges. Productization progressed steadily and the screen was released for sale considerably earlier than the completion of the diamond screen. Nunobiki Manufacturing named it a slotted grill and also patented its manufacturing method.
These slotted grills, like the diamond screens, are still the only products of their kind sold in Japan.