Development of ultra-fine-grain binderless cBN tool for precision cutting of ferrous materials

Abstract

A new cutting tool was developed from ultra-fine-grain (<100 nm), binderless cubic boron nitride (cBN) material fabricated by transforming hexagonal boron nitride to cBN by means of sintering under an ultra-high pressure of 10 GPa at 1800 ºC. The cutting edges of the newly developed cBN tool can be made as sharp as those of single-crystal diamond tools. In this experiment, cBN and single crystal diamond tools of the same shape were compared by precision cutting tests using stainless steel specimens and steel specimens coated with an electroless Ni-P layer. The surface roughness (R z ) of specimen surfaces cut with the cBN tool by means of planing was approximately 100 nm for both the Ni-P-coated steel and stainless steel specimens. Though similar R z values were obtained for Ni-P layers cut by the cBN and diamond tools, an R z value exceeding 2000 nm was obtained for stainless steel cut by the diamond tool. High-precision surfaces with R z values of 50 -100 nm were obtained for stainless steel specimens cut with the cBN tool under high-speed milling (942 m/min) conditions. These results indicate that the newly developed cBN tool is useful for the ultra-precision or precision cutting of ferrous materials.

High speed turning of Inconel 718 using PVD-coated PCBN tools

“…During subsequent decades the range of PCBN products expanded with grades encompassing variations in cBN grain size (~0.5-10 µm) and binder content (~2-60%) together with an extended range of associated ceramic materials and reinforcement in order to allow for wider work material usage and improved performance [1]. Focus has also recently centred on binderless cBN products with applications including ultraprecision machining of hardened steels [2,3].…”

Optimization of Cutting Data and Tool Inclination Angles During Hard Milling with CBN Tools, Based on Force Predictions and Surface Roughness Measurements

“…. ,n. At this stage, the nominal cross-section of the machined layer is also determined and the efficiency of the machining process Q f_i = a e_i • f i [mm 2 /min] and cutting force components, e.g., F t_i are calculated. Calculations of the cutting force components are performed using FEM, and they can be optionally replaced by measurements.…”

“…Cubic boron nitride (CBN) is an extremely hard material with excellent physical and chemical properties such as heat resistance, high modulus and weak reaction of other elements [1]. CBN, unlike diamond and due to the lower reactivity with the iron, is suitable for the machining of steel [2]. So, besides the grinding and electrical discharge machining process (EDM), cutting tools made of CBN are suitable in the production of molds and dies in the hard state, in precise and very precise operations of roughing [3][4][5][6].…”

Mechanical Properties of Cubic‐BN(111) Bulk Single Crystal Evaluated by Nanoindentation

“…Boron nitride (BN) has several polytypes, including hexagonal (h‐), cubic (c‐), and wurtzite (w‐). Currently, h‐BN and c‐BN are used in various applications such as lubricants, crucibles, and cutting instruments . Recently BN has also received attention as a semiconducting material.…”