Introduction
This document introduces the new CBN small diameter ball nose endmills, specifically the Type BNBP, designed for high precision machining of hardened steels with a hardness of less than HRC70. The endmills feature a high accuracy of ±0.005mm and are made from the super tough grade SUMIBORON BN350, which prevents chipping of the cutting edge.

Performance Specifications
The R1.0 ball endmill is tested on X155CrVMo12-1 material with a hardness of HRC60. The cutting data includes a spindle speed of 20,000 rpm, a feed rate of 0.05 mm/tooth, and a cutting speed of 2,000 mm/min. The depth of cut (doc) and width of cut (woc) are both 0.05 mm, with air blast cooling.

Wear Resistance
Compared to competitor's CBN and coated carbide endmills, the SUMIBORON BN350 demonstrates excellent surface finish and wear resistance. The tool life is noted to be 10 times longer under high-speed machining conditions with a spindle speed of 40,000 rpm and an oil mist cooling system.

Recommended Cutting Conditions
For stable machining, a rigid machine is recommended. The use of air blast or oil mist coolant is advised, and the overhang should be minimized. The recommended spindle speed ranges from 20,000 to 50,000 rpm, with varying feed rates and depths of cut depending on the radius of the ball nose.

Product Specifications
The document lists various stock dimensions for the BNBP series, including different radii, shank diameters, and neck lengths. The endmills are suitable for machining pre-hardened steel, die steel, and high-speed tool steel.

Contact Information
For distribution in Germany, contact SUMITOMO ELECTRIC Hartmetall GmbH, and for the UK and Ireland, contact SUMITOMO ELECTRIC Hardmetal Ltd. Contact details and websites are provided for further inquiries.