With the development of IT-related industries and technological progress, related parts and their processing molds are increasingly miniaturized. Most of the small precision molds use electrical discharge machining, which requires long processing time and low efficiency. The technical problems of the electrode and its manufacturing process must also be solved. In order to shorten the delivery time and reduce the production cost, the processing method is gradually turning to high-speed milling of the cavity with a small diameter ball end mill. In addition, efficient machining methods (high-speed milling) that reduce the cutting depth, increase the cutting speed, and maximize the feed rate are also increasingly popular. In this context, CBN end mills with a longer service life than coated carbide end mills have attracted much attention. This article briefly introduces the CBN small-diameter ball nose end mill CBN-SXB developed by Japan's OSG Company for machining high-hard steel mold cavities.