Cubic boron nitride cutting tools

Cubic boron nitride tool type and use:

Cubic boron nitride cutting tools in the past mainly for finishing, the last decade by improving the production process, raw material purity and grain size control, the use of composite materials and other hot-pressing process, the significant improvement of its brittleness, toughness, the use of reliable greatly improved as a routine tool has been applied in production, to improve efficiency, ensure product quality plays an important role.

Cubic boron nitride cutting tools to develop new trends:Cubic boron nitride cutting tool is an advanced tool, a bright future. Semi-finishing and finishing first in time, in some cases even roughing operations, with its hardened steel, chilled cast iron, 35HRC or more of cobalt and nickel-based superalloys and other difficult materials is also effective . For example, the Russian T-10 (PCBN) inserts with good impact resistance, it can be used semi-finishing and finishing, can also be used to eat back cutter roughing capacity of 6mm. Cubic boron nitride is currently the world's annual consumption of about 10% to 15% growth rate.Synthetic superhard cubic boron nitride cutting tool materials, the present single crystal of the coarse particles, high-intensity, multi-direction. Japanese production of single crystals of inorganic materials CBN diameter of 3mm. De Beers produced PCBN products, maximum diameter of 101.6mm, and then laser cut into any shape required, the high hardness materials can be processed 70HRC.Cubic boron nitride cutting tool materials more expensive, in order to expand its scope of application, has been developed abroad, price is relatively low compared with the cubic boron nitride coated tools. It is the use of chemical vapor deposition (CVD) in general-purpose tungsten-cobalt (K) type carbide substrate (in principle, can be coated in any base body) coated with a thin layer of cubic boron nitride superhard materials. Britain has also developed a PCBN inserts on the coating layer with a CVD method nickel, copper, titanium, chromium, tantalum, cobalt compounds, as well as TiN or TiC protective coating, high wear resistance than ordinary PCBN inserts 3 times. Lellond by the company developed a ceramic and CBN superhard composite materials, which combines the advantages of these two materials, high-speed machining is ideal for hard wear-resistant cast iron materials.Cubic boron nitride cutting tools depends on the widespread use of high-speed, high rigidity, high vibration resistance of the metal cutting machine tools, and new varieties of high-strength grades of blades, depending on processing conditions and should select the appropriate cutting parameters to be processed with material phase "matching." The current development of cubic boron nitride cutting tools, on the one hand to try to improve the quality of the blade to reduce blade costs; the other hand, further developed the finer grain size materials to increase their density, reducing the edge serrated edge, so that it can edge worn more sharp, but to solve the cubic boron nitride tool sharpening to improve the efficiency and quality.


 Cubic boron nitride cutting tool materials, performance characteristics

Cubic boron nitride cutting tools is the use of cubic boron nitride (CBN) made ​​some cutting tool. Cubic boron nitride (CBN) is a boron nitride BN isomers of the same elements, with the diamond structure is similar to ultra-high temperature high pressure technology with synthetic superhard materials. Its hardness only to diamond (hardness up to 8000 ~ 9000HV), and high thermal stability (up to 1250 ~ 1350 ℃), chemical inertness of the iron group elements, anti-bonding ability, you can use the diamond grinding wheel the blade, so for more than 35HRC machining hard materials, such as a variety of hardened steel (carbon tool steel, alloy tool steel, high-speed steel, bearing steel, tool steel, etc.), chilled cast iron, cobalt and nickel base high-temperature alloys, tungsten carbide, surface coating (solder) materials and high hard wear-resistant materials can also be used for titanium alloys, pure nickel, pure tungsten and other materials processing. It is a car, instead of grinding mill one of the best tools. Cubic boron nitride cutting tools with hardened steel surface roughness Ra1.60.4μm, accuracy up to IT7IT6. Figure 1 shows the hard turning with CBN cutting tools tungsten alloy case.

Cubic boron nitride cutting tools have limitations on the use, as it more brittle, less strength and toughness, not to break under shock loading surface processing. In addition, it processed the iron group elements of soft materials, because of easy to produce long chips, scratches, tool rake face and the formation of BUE, cutting force fluctuations will lead to damage to the tool.In order to improve the impact resistance of boron nitride cutting tools, has developed a class of graphite, hexagonal boron nitride with (g-BN or h-BN) as raw material, explosive synthesis of a new type of WBN material (WBN is an lead-zinc structure BN). It has a very high toughness and sintering activity, easily transformed into CBN, and easy and CBN sintered together into a strength and hardness close to the level of poly-CBN crystals.WBN and two-phase sintered CBN is used to make up for the toughness of CBN WBN brittle, its impact strength than pure CBN sintered body by 60%, an increase of 2.53 times the fracture toughness, resistance to flexural strength increased by 1 times, anti- compressive strength and carbide considerable thermal stability for the 1100 ~ 1200 ℃. Can be used to break the surface of the workpiece processing, such as gear tooth surface, welding the workpiece surface or a groove.Currently, WBN and two-phase sintered CBN tools in the U.S., Japan and Russia and other countries in the automotive industry wide application, such as for processing link, quite cylinder, cylinder liners, brake wheel, crankshaft, flywheel, the types of pump shell-type parts of the car, boring and milling processes.1 type of cubic boron nitride cutting toolsAt present the production of cubic boron nitride cutting tools commonly used in three ways: overall polycrystalline cubic boron nitride (PCBN) cutting tools, polycrystalline cubic boron nitride and carbide composite blade (PCBN / CC) and plated cubic boron nitride cutting tools . Among them, two types of tool use most.PCBN at high temperatures, high pressure, the number of polycrystalline CBN single crystals into polycrystalline material powder is sintered CBN crystal powder. PCBN / CC is in the strength and toughness of cemented carbide substrate, sintered or pressed 0.5 ~ 1mm thick layer made of a composite blade PCBN, it solves the cubic boron nitride blade bending strength and low inlay welding difficult issues. PCBN / CC welding or machine clip free way of making knives. For example, U.S. GE (General Electric) produced BZN blade, Russia's Toma-10 blade, the Japanese company Sumitomo Electric BN blades, as well as China's production of LDP-J-CF, DLS-F, LF, and LBN-Y-type series PCBN inserts are composite blades.Electroplated cubic boron nitride cutting tools is buried in sand plating method to nickel, copper and cobalt as binder, the CBN package inserts of fine particles in a certain size and geometry of the base surface of the tool surface, through the appropriate grinding is made. Zhengzhou Institute of abrasives grinding CBN plating production is such a reamer tool. Figure 2 - Figure 4 shows the production of several commonly used cubic boron nitride cutting tools.

Undo edits

Cubic boron nitride cutting tools in the past mainly for finishing, the last decade by improving the production process, raw material purity and grain size control, the use of composite materials and other hot-pressing process, the significant improvement of its brittleness, toughness, the use of reliable greatly improved as a routine tool has been applied in production, to improve efficiency, ensure product quality plays an important role.Cubic boron nitride cutting tool materials, performance characteristicsCubic boron nitride cutting tools is the use of cubic boron nitride (CBN) made some cutting tool. Cubic boron nitride (CBN) is a boron nitride BN isomers of the same elements, with the diamond structure is similar to ultra-high temperature high pressure technology with synthetic superhard materials. Its hardness only to diamond (hardness up to 8000 ~ 9000HV), and high thermal stability (up to 1250 ~ 1350 ℃), chemical inertness of the iron group elements, anti-bonding ability, you can use the diamond grinding wheel the blade, so for more than 35HRC machining hard materials, such as a variety of hardened steel (carbon tool steel, alloy tool steel, high-speed steel, bearing steel, tool steel, etc.), chilled cast iron, cobalt and nickel base high-temperature alloys, tungsten carbide, surface coating (solder) materials and high hard wear-resistant materials can also be used for titanium alloys, pure nickel, pure tungsten and other materials processing. It is a car, instead of grinding mill one of the best tools. Cubic boron nitride cutting tools with hardened steel surface roughness Ra1.60.4μm, accuracy up to IT7IT6. Figure 1 shows the hard turning with CBN cutting tools tungsten alloy case.
Figure 1 Turning with CBN cutting tools tungsten-based alloysShanghai General Motors engine in a flexible production line, with Seco Tools (Shanghai) Company production of cubic boron nitride CBN300 engine block milling cutter blade surface plane (casting), cutting speed up to 1600m/min, feed rate of 5000mm / min. Table 1 lists the two kinds of superhard cubic boron nitride and diamond material properties of the contrast.Table 1 cubic boron nitride diamond properties in comparison
Cubic boron nitride cutting tools have limitations on the use, as it more brittle, less strength and toughness, not to break under shock loading surface processing. In addition, it processed the iron group elements of soft materials, because of easy to produce long chips, scratches, tool rake face and the formation of BUE, cutting force fluctuations will lead to damage to the tool.In order to improve the impact resistance of boron nitride cutting tools, has developed a class of graphite, hexagonal boron nitride with (g-BN or h-BN) as raw material, explosive synthesis of a new type of WBN material (WBN is an lead-zinc structure BN). It has a very high toughness and sintering activity, easily transformed into CBN, and easy and CBN sintered together into a strength and hardness close to the level of poly-CBN crystals.WBN and two-phase sintered CBN is used to make up for the toughness of CBN WBN brittle, its impact strength than pure CBN sintered body by 60%, an increase of 2.53 times the fracture toughness, resistance to flexural strength increased by 1 times, anti- compressive strength and carbide considerable thermal stability for the 1100 ~ 1200 ℃. Can be used to break the surface of the workpiece processing, such as gear tooth surface, welding the workpiece surface or a groove.Currently, WBN and two-phase sintered CBN tools in the U.S., Japan and Russia and other countries in the automotive industry wide application, such as for processing link, quite cylinder, cylinder liners, brake wheel, crankshaft, flywheel, the types of pump shell-type parts of the car, boring and milling processes.1 type of cubic boron nitride cutting toolsAt present the production of cubic boron nitride cutting tools commonly used in three ways: overall polycrystalline cubic boron nitride (PCBN) cutting tools, polycrystalline cubic boron nitride and carbide composite blade (PCBN / CC) and plated cubic boron nitride cutting tools . Among them, two types of tool use most.PCBN at high temperatures, high pressure, the number of polycrystalline CBN single crystals into polycrystalline material powder is sintered CBN crystal powder. PCBN / CC is in the strength and toughness of cemented carbide substrate, sintered or pressed 0.5 ~ 1mm thick layer made of a composite blade PCBN, it solves the cubic boron nitride blade bending strength and low inlay welding difficult issues. PCBN / CC welding or machine clip free way of making knives. For example, U.S. GE (General Electric) produced BZN blade, Russia's Toma-10 blade, the Japanese company Sumitomo Electric BN blades, as well as China's production of LDP-J-CF, DLS-F, LF, and LBN-Y-type series PCBN inserts are composite blades.Electroplated cubic boron nitride cutting tools is buried in sand plating method to nickel, copper and cobalt as binder, the CBN package inserts of fine particles in a certain size and geometry of the base surface of the tool surface, through the appropriate grinding is made. Zhengzhou Institute of abrasives grinding CBN plating production is such a reamer tool. Figure 2 - Figure 4 shows the production of several commonly used cubic boron nitride cutting tools.
Figure 2 CBN machining fabricated parts of the shell face milling cutter

Figure 3 of the boring tool with CBN inserts

Figure 4 plated CBN reamersThe correct selection of varieties and grades of bladeDifferent species of PCBN cutting tools, because of its composition is different from cutting are very different, to be used to pay attention. PCBN cutting tools like carbide present in the international arena as a unified classification of all plants have their own varieties and grades, the use of samples to be selected with reference to vendor products.The performance of PCBN and CBN particle size, content and the kinds of binders, their organization can be divided into two categories: one is without bond by the CBN sintered grain directly, CBN content and more (70% above), high hardness, suitable for heat-resistant alloys, cast iron and iron-based sintered metal cutting; the other is based on CBN grains as the main body, through the ceramic binder (mainly TiN, TiC, TiCN, AlN, Al2O3, etc. ) sintering, such CBN content PCBN in less (70%), low hardness, suitable for continuous cutting of hardened steel.For high-speed interrupted cutting of hardened steel machining, the choice of foreign PCBN newly developed new varieties Sumiboron BNX25, it has a high resistance to crater wear ability of high-speed intermittent cutting tool fracture and failure caused by a broken very high resistance. When machining hardened steel with BNX25 recommended cutting conditions are cutting speed of 120 ~ 200m/min, feed rate of 0.15 ~ 0.3mm / r and the knife back to eat the amount of 0.2 ~ 0.5mm.CBN grain size can be divided into three categories: coarse grain (average grain size of 20 ~ 50μm), the grain size (10 ~ 20μm) and fine grains (2 ~ 10μm). Larger grain size, the better wear resistance, higher tool life, but poor quality edge, made of high-precision hard cutter. In contrast, fine-grained tool, the cutting edge of the edge of good quality, surface finish and good quality. Thus continue to refine the current grain polycrystalline and have 1μm, 0.5μm and even less fine-grained, be based on rough and finish requirements of different processes, use of different grain sizes.(2) a reasonable selection of tool geometryAs the cubic boron nitride material brittle, low strength, so the tool rake angle is usually taken to γ0 = 0 ° ~ -5 °, clearance angle α0 = 6 ° ~ 15 °. In order to improve edge strength, edge chamfering on the negative to be grind, chamfer width desirable br1 = 0.1 ~ 0.3mm, chamfering front γ0 =- 6 ° ~ -20 °; tip with appropriate rounding, rounding radius rε = 0.2 ~ 0.8mm. However, rounding the tip radius and the greater the negative chamfering, cutting force will increase, the chance occurrence of flutter also increased. So when the machine - fixture - tool - workpiece system rigidity is insufficient, especially in the processing of thin workpiece, should not use the tip radius is too large and negative chamfer.