Cubic boron nitride Overview

CBN is a hexagonal lattice of boron nitride (H-BN) under heat and pressure, the activator effect polymerization conversion into high-density cubic lattice (C-BN)

single crystal, the crystal type structure similar to diamond, its hardness only to diamond of 7000 ~ 9000HV, the boron and nitrogen atoms, and its chemical and

thermal stability than carbon atoms in diamond. Widely used for machining hardened steel, chilled cast iron, heat-resistant alloys and other ferrous metals.
Brief introduction
cubic boron nitride single crystal particles is very small, only can be used for abrasives. In order to make the tool, it needs to be further various combinations with

or without agent (phase) and then sintered at high temperature high-pressure polymerization of PCBN PCBN isotropic polycrystalline block. It is made with high speed

and efficiency to meet a variety of processing requirements, the overall composite as a whole or with carbide blade (PCBN time usually about 0.5mm thick), then it is

welded or mechanical clamping into various Use of the tool, which known CBN cutting tools.
Feature
Cubic boron nitride (CBN) in hardness only to diamond. And the diamond is different, it is in the processing of ferrous metals chemical reaction hardly occurs. Through

a high-temperature high-pressure technology, people can carbide layer is bonded tightly homogeneous poly crystal cubic boron nitride coating. This poly-crystalline

cubic boron nitride referred PKB. BZN * - blades can replace conventional grinding process for hardening steel material treated (HRC45-68) also enables high-speed

finishing, cutting speed can reach 80-200m/min. BZN * - pearlitic cast iron blade is also used for cutting and hard cast iron and alloy cast iron.
Method
A single crystal cubic boron nitride sintered body and polycrystalline two kinds.
Single crystal is hexagonal boron nitride and the catalyst at a pressure of 3000 to 8000 MPa, the temperature is within the range 800 ~ 1900 ℃ system. Typical

catalyst materials selected from alkali metals, alkaline earth metals, tin, lead, antimony and their nitrides. Cubic boron nitride crystal with tetrahedral truncated

cone, octahedron, distorted crystal and double crystal, etc.). Industrial production CBN black, amber and surface metallization, the particle size is usually below 1

mm. It has superior thermal stability of diamond and iron group metals chemically inert, for the manufacture of abrasive, suitable for processing both hard and tough

materials such as high-speed steel, tool steel, tool steel, bearing steel, nickel and cobalt-based alloy, chilled cast iron. CBN abrasive grinding with steel, the most

grinding ratio and obtain high surface quality.
Polycrystalline cubic boron nitride sintered body of the main system of law are: ① a cubic boron nitride powder and a small amount of binding agent (such as cobalt,

aluminum, titanium, titanium nitride, etc.) at a pressure of 4000 to 8000 MPa, a temperature of 1300 ~ 1900 ℃ sintered under; ② to cubic boron nitride powder and a

binding agent layer to carbide (sheet or powder) as a layer, the above pressure and temperature, the two sintered together to obtain a cemented carbide substrate with

a polycrystalline sintered body, this sintered body has high strength, while maintaining the original physical and chemical properties of cubic boron nitride, can be

made up to 16 mm in diameter of the wafer, after cutting into a suitable shape as turning and boring knife blade, suitable for cutting hardened steel, cast iron and

nickel-based alloys.
Application
CBN grinding tools and tool mainly used for the production, that is used for grinding and cutting. CBN abrasives and abrasive products (corundum, silicon carbide

abrasive), compared with grinding sharp, good wear resistance, high processing efficiency (ease of automation), excellent surface quality (inside surface compressive

stress), high precision, long life, low unit processing cost, energy-saving and environmental improvement, etc., so it is widely used in automobiles, tractors,

bearings, machine tools, gear, tools, abrasives, aerospace, military and many other industries, particularly for high-speed steel, heat-resistant steel, stainless

steel, heat-sensitive materials, high hardness, toughness, high temperature strength, low thermal conductivity materials, precision grinding.
Ceramic CBN grinding not only has sharp cutting, cutting force is small, high efficiency, long life, easy shaping and sharpening, grinding, high precision, but also

has grinding workpiece temperature is low, the surface can eliminate residual tensile stress stress, so that the workpiece durability increased by 30% -50% of the

characteristics, therefore, vitrified CBN grinding to get the sudden emergence in recent years of development.

Abrasives Outline

Abrasives Outline
Abrasives, abrasive and grinding tools are referred to, including abrasive products and abrasive products. Known as dental abrasives industry reputation. Commonly used

in the grinding or abrasive abrasive grinding tool as the machining of parts to be machined to achieve the certain technical requirements.
Abrasive Category
Wherein the abrasive products are mainly divided abrasive corundum and silicon carbide abrasive two categories, specifically, there are basically the following:
1, corundum abrasive, the main component of Al2O3, with medium hardness, toughness, particle Fengrui, relatively inexpensive, suitable for machining high tensile

strength of the metal. Microcrystalline corundum abrasives and black corundum abrasives are its derived varieties.
2, white fused alumina abrasive, slightly higher than the hardness of corundum, but poor toughness, easy to cut into the workpiece during grinding, good self-

sharpening, less heat, grinding ability, high efficiency. Chromium corundum abrasive is its derived varieties.
3, single crystal corundum abrasive material particles are composed of a single crystal, and has a good polygonal cutting edge, high hardness and toughness, grinding

ability, less grinding heat, the disadvantage is the high cost of production, yield lower, so the price is relatively high. Corundum abrasives are also crystalline

compound, slightly lower hardness, crystal size is fine, good wear resistance.
4, black silicon carbide abrasive, green silicon carbide abrasive, abrasive cubic silicon carbide, silicon carbide abrasive cerium, etc., are silicon carbide abrasive,

the main ingredient is silicon carbide SiC, high hardness, brittleness, sharp abrasive grains, good thermal conductivity, strong wear resistance, more suitable for

processing hard and brittle metallic and non-metallic products.
Abrasives Classification and Development
Is for abrasive grinding , grinding and polishing tools. Most of the abrasive is made of abrasive plus artificial abrasive binding agent, is also useful natural mineral

rock directly processed into natural abrasive. In addition to grinding and other metal processing machinery manufacturing industry has been widely used, but also for

food processing, paper industry and the ceramics, glass, stone, plastic, rubber, wood and other non-metal materials processing.
Abrasive in use, when the blunt abrasive, because the abrasive agent or a combination of its own to break fracture, the abrasive grain from the partial or complete

loss, the working surface of the Abrasive grinding emerging new cutting edge, sharp or continuously exposing new abrasive grains, the abrasive can be maintained within

a certain time cutting. This self-sharpening abrasive is abrasive tool compared with the general prominent feature.
As early as the Neolithic Age, humans had already started to process the application of natural stone knives, stone axes, bone, horn, and tools such as a tooth; 1872,

appeared in the United States with natural abrasives combined with clay firing ceramic grinding wheel; 1900 years ago, the advent of artificial abrasives, using

artificial abrasives manufacturing have produced a variety of abrasives for grinding and grinding create the conditions for rapid development. Since then, natural

abrasive in the abrasive proportion gradually reduced.
Abrasives source of their raw materials, with natural and artificial abrasive abrasive categories. Commonly used in machinery industry is only natural abrasive

Whetstone. Artificial abrasive characteristics according to the basic shape and structure of the distinction between a grinding wheel, grinding, stone, sand tile (the

foregoing collectively referred abrasive) and coated abrasives five. In addition, it is customary also put abrasives abrasive as a class.
Bonded Abrasives are used by different abrasives can be divided into ordinary abrasive abrasive and superabrasive abrasive. The former corundum and silicon carbide and

other common abrasive, the latter with diamond and cubic boron nitride and other superhard abrasive material. In addition, there are some special varieties, such as

sintered corundum abrasive and so on.
By ordinary abrasive abrasive abrasive solid binding agent to form a certain shape common, and has a certain strength abrasive. Generally abrasive, binder and pore

structure, these three parts are frequently referred to as the three elements of abrasive.
Abrasive abrasive cutting action play. Binding agent is a solid form of the abrasive loose abrasive materials, with inorganic and organic types. Inorganic binder with

ceramic, magnesite, sodium silicate and the like; organic a resin, rubber and shellac. One of the most commonly used is a ceramic, resin and rubber binding agent.
Holes in the ground when debris from the role of the chip and the chip, and can accommodate coolant, helps grinding heat dissipation. To meet the requirements of

certain special processing, the pores can be impregnated with certain fillers such as sulfur and paraffin, so as to improve the abrasive performance. Such fillers,

also known as the fourth element of the abrasive.
Means a common abrasive abrasive characteristics of the project are: shape, size abrasive, grain size, hardness, structure and bonding agent. Abrasive abrasive

hardness refers to the external force from the abrasive surface of the shedding of degree of difficulty, it reflects the strength of binding agent holding abrasive.
The hardness of the abrasive agent is added depends on the amount of binding and the density of abrasive, abrasive grains easily fall off indication low hardness; vice

versa, which means high hardness. Hardness level is generally divided into super-soft, soft, medium soft, medium, medium-hard, hard and superhard seven magnitude, from

these levels can be subdivided in a number of small magnitude. Abrasive hardness measurement methods are more commonly used hand cone, mechanical cone method, Rockwell

hardness measurement method and sandblasting assay.
The hardness of the abrasive and its dynamic modulus of elasticity has a corresponding relationship, which is conducive to the audio abrasive measured dynamic elastic

modulus of said abrasive tools. In the grinding process, if they are grinding workpiece material hardness, generally used in low hardness abrasive; Conversely, the

selection of high hardness abrasive.
Grinding of crude into tight, medium and loose categories. Each category can be further subdivided and number, with the numbers to differentiate between organizations.

Abrasives organization number greater share of the abrasive grinding smaller volume percentage, the wider the gap between the grains, which means that more loose

tissue. On the contrary, the smaller the number of organizations expressed more tightly organized. Loose organization is not easy to use abrasive passivation less heat

during grinding, the workpiece can reduce heat deformation and burns. Tight organization abrasive grit easy to fall off, helps maintain the abrasive geometry.

Abrasives organization only in the manufacture of abrasive formulations are controlled by, generally do not make determination.
Abrasives - Uses
Grinding, polishing, grinding, cleaning, cutting, drilling.

Single crystal diamond

Single crystal diamond cutting tools must be used for large particles (mass greater than 0.1g, the best path length not less than 3mm), mainly used in surface

roughness, geometry, high precision and dimensional accuracy requirements of precision and ultra precision machining applications fields.
Natural diamond single crystal diamond is the most wear-resistant material. Fine texture of its own, after fine grinding, cutting edge edge edge radius as small as

0.008 ~ 0.005μm. But more brittle natural single crystal diamond, the crystal anisotropy, different surfaces or in the same plane

Crystal hardness in different directions were different, and must be used during the sharpening choose the right direction. The use of harsh conditions, coupled with

natural single crystal diamond resources are limited, the price is very expensive, so they use a production PCD, PCD / CC and CVD diamond

Tools. Some natural single crystal diamond is mainly used for ultra-precision machining non-ferrous metals or gold jewelry production.
synthetic diamond single crystal diamond the size, shape and performance are in good agreement, present due to high pressure technology matures, a certain size can be prepared

by synthetic single crystal diamond, especially in the processing of high wear-resistant laminated wood, it performance to be

Than PCD diamond cutting edge will not cause premature passivation

Application of diamond tools

Natural diamond tools currently used mainly for copper and copper alloys and gold, silver, rhodium and other precious metals, and special parts of the ultra-precision

mirror processing, such as a disk recorder, an optical mirror, a polygon mirror and the second curved mirror and so on. But its crystalline anisotropy, the tool

Expensive. PCD performance depends on the content of diamond grains and cobalt, cemented carbide tool life (WC substrate) of the tool 10 to 500 times. Turning is

mainly used for various non-ferrous such as aluminum, copper, magnesium and their alloys, tungsten carbide fibers and strong wear resistance

Plasticized materials, metal matrix composites, wood and other non-metallic materials. When cutting speed, feed rate and depth of cut depends on processing conditions

and the hardness of the workpiece material. synthetic diamond polycrystalline diamond compact (PDC) properties and applications close PCD tools, mainly

Used in non-ferrous metals, tungsten carbide, ceramics, non-metallic materials (plastic, hard rubber, carbon rod, wood, cement products, etc.), composite materials

cutting, gradual replacement carbide cutting tools . Because the diamond particles bonded to ask some residual metals and graphite,

Bonding metal to which the state or in the form coalesced vein-like distribution will reduce tool wear and life. In addition there is a metal residue solvent, solvent

metal in direct contact with the diamond surface. Lower (PDC) antioxidant capacity and tool heat resistance, it is not enough cutting tool

Stability. Thick Diamond Tool preparation process is complex, because of the low melting point metals and their alloys and diamond has a high interfacial energy

between. Diamond is difficult to be generally low melting point solder alloy infiltration. Weldability poor, difficult to produce complex geometry tool, so TDF

Welding tool can not be used in high-speed milling. Diamond-coated tools can be applied to high-speed machining, because in addition to diamond coated tools have

excellent mechanical properties, diamond coating process can be prepared any complex shape cutters for high speed machining, such as aluminum

Difficult to machine titanium aerospace materials and non-metallic materials such as graphite electrodes.

Diamond coated tools

Diamond coated tools with diamond coated tools directly in the carbide CVD method (K type carbide) or ceramic layer deposited on the substrate 1 ~ 25μm diamond films,

no cleavage plane isotropic. Figure 3 (b). Film coated tool hardness of 9800 ~

10000HV. High thermal conductivity, thermal conductivity at room temperature up to 2000W · m-1 · K-1, while the carbide thermal conductivity is only 80 ~ 100m-1 ·

K-1. Diamond CVD method may be coated to any complex shape of the tool, which is not owned by the polycrystalline diamond

The most significant advantage.
Cubic boron nitride (PCBN) cutting tools cubic boron nitride (PCBN) is the second synthetic diamond that appears after the second inorganic superhard materials, its

slightly inferior to diamond hardness, good thermal stability, heat resistance up to 1400 ~ 1500 degrees, the heat resistance than diamond (700 to 800 degrees) Quite

Almost twice as high. Cubic boron nitride (PCBN) cutting tools is mainly suitable for processing a variety of ferrous metals and their alloys; most suitable for a

variety of hardened steel (carbon tool steel, bearing steel, tool steel, high speed steel) pearlitic gray cast iron (vanadium-titanium iron) chilled cast superalloys

(nickel-based alloys

Cobalt-based alloys) and surface coating welding processing. Has a long life and reduce the number of tool changes, compensation down the time spent for NC machine

tools and automated production line efficiency can be more fully exploited, can change the traditional machining way (ie, before quenching with a tool

Wheels for roughing and finishing after quenching method), which can be on a CNC machine before quenching after quenching turning (turning instead of grinding), with

good economic benefits.

Polycrystalline diamond cutting tools

polycrystalline diamond (PCD) cutting tools PCD high temperature high pressure conditions by cobalt and other metal-bonded to synthetic diamond powder sintered

polycrystalline material gathered, also known as sintered diamond. Overall sintered polycrystalline diamond cutter cutter for milling, PCD grain was

Disordered arrangement state, is isotropic, uniform hardness, graphitization temperature is 550 ℃. Tool has high hardness, high thermal conductivity, low thermal

expansion coefficient, high elastic modulus and a low coefficient of friction. They are very sharp and so on.
Synthetic polycrystalline diamond compact (PDC) tool to improve PCD inserts toughness and weldability, often the PCD and carbide composite body made of synthetic

polycrystalline diamond blade (PDc). The surface of the cemented carbide substrate being suppressed 0.5 ~ 1mm thick layer of sintered PCD

. The flexural strength of the composite blade with carbide consistent hardness close to PCD, PCD can replace the use. PCD and synthetic polycrystalline diamond

compact (PDC) cutter sharp edge and workpiece surface quality than ND. While its workability is poor,

Grinding ratio is small, it is difficult according to the geometry of any head shape. Current use of synthetic polycrystalline diamond compact Preparation Tool only,

still can not be manufactured with chipbreaker indexable inserts and complex three-dimensional surface geometry cutter.
CVD diamond films (TDF) welding tool welding thick diamond cutting tool is good to laser welded to a CVD diamond thick film substrate (usually a class K carbide) to

form a composite sheet, and then polishing composite sheet, the second welding to the cutter body, sharpening as needed

Shape and edge. Figure 3 (a) shows, for the CVD diamond films (diamond film thickness of 30μm), with high hardness, wear resistance, low coefficient of friction,

etc., is to create cutting non-ferrous metals and non-metallic materials, the ideal tool materials. As Diamond Welding

Process complex process, CVD diamond films (TDF) welding tool yet high-volume applications.

Abrasive blasting
Brief introduction
Abrasive blasting abrasive short time, high efficiency, good benefits, and low prices. The product hardness, high toughness, good self-sharpening, sand consumption is

low and can recycle and reuse, grinding wheel pieces of finish is good; and chemical stability, wear resistance, acid and alkali. The abrasive media

Shell-shaped fracture, sharp corners, constantly smashing step in the formation of new edges and the side edge, making it superior to other Abrasive grinding capacity.

In particular it has a high hardness, specific gravity, chemical stability and its unique advantages of a self-sharpening abrasive blasting process used

Preferred; while the workpiece is cleaned sand-blasting, grinding and polishing the ideal material.
Principle
Abrasive blasting is the use of compressed air as a driving force to form a high-speed jet beam will spray material (copper sand, quartz sand, emery, iron ore, Hainan

sand) high-speed jet to the need to deal with the surface, the outer surface of the workpiece surface appearance or shape changes, since the

Abrasives on the surface of the impact and cutting action of the workpiece surface to obtain a different cleanliness and roughness of the workpiece surface to improve

the mechanical properties, thus improving fatigue resistance of the workpiece, and the coating of increased its adhesion between, extend the

The durability of the coating, but also conducive leveling and decorative coatings.
Precautions
1, before work must wear protective supplies, are not allowed to work naked arm. Work will not be less than two.
2, gas tank, pressure gauge, safety valve to regularly check. Tank two weeks once the dust emission, Shaguan inside the filter once a month.
3, check the vent pipe and blasting machine door is sealed. Work five minutes, shall actuate ventilation dust removal equipment, ventilation and dust removal equipment

failure, prohibit blasting machine work.
4, the compressed air valve slowly open, pressure must not exceed 0.8MPa.
5, sandblasting size should be adapted to the requirements of work, usually in ten to twenty number are applicable, sand should be kept dry.
6, sandblasting machine work, prohibit close. Cleaning and adjusting the operation site should be shut down.
7, who are not allowed to use compressed air to blow dust or joking.
8, after work, ventilation and dust removal equipment should continue to operate for five minutes and then off to discharge indoor dust, keep clean.
9, the occurrence of physical, equipment accidents, should be kept on-site, and report the relevant departments.