Graphite heat sink, is a kind of new heat conduction material, has a unique grain orientation, along the two directions of uniform heat, film layered structure can be well adapted to any surface, shielding heat source and components of the same time to improve the performance of consumer electronics products. Products even heat dissipation in the thickness of the heat insulation. The molecular structure of the thermal conductive graphite sheet is as follows:

　　The unique thermal and thermal insulation properties of graphite heat conduction solution make the thermal conductive graphite to be an outstanding material for heat management solution. The thermal conductivity of the graphite film plane has a high thermal conductivity within the range of W/m-K 150-1500.

　　Flexible Graphite sheet C (Thermal) is a natural element, which can be used as a kind of natural element, which can be used in many fields such as electronic, communication, lighting, air and defense industry. It has been widely used in electronic, communication, lighting, air defense and other fields because of its good properties.

　　Graphite heat conduction material provides a unique solution to the heat management industry. Heat conduction graphite materials through a series of different heat management solutions to the growing demand for industrial cooling technology to bring new technology to provide a new technology for hot graphite material products to provide a new technology for electronic industrial heat management. Thermal conductive graphite in the case of reducing the weight of the device to provide a more excellent thermal performance, thermal conductivity graphite thermal solution is a new application of thermal design. Thermal design of electronic equipment for thermal conduction graphite.

　　The advantages of the graphite heat sink

　　1. Low thermal resistance: thermal resistance is 40% lower than that of aluminum, which is lower than 20%

　　2.Light weight: weight is lighter than aluminum 25%, 75%

　　3.High thermal conductivity: graphite heat sink can be smooth and attached to any plane and curved surface, and can be in accordance with the needs of customers for any form of cutting.

      1, Graphite can be used as a refractory material: graphite and its products have properties of high - strength, high temperature resistance, mainly used to produce graphite crucible in the metallurgical industry, in steelmaking in graphite is usually used for the protection of steel ingot agent, metallurgical furnace lining.

　　2, Graphite can be used as the conductive material: used for manufacturing electrode, carbon brush, carbon rod, carbon nanotubes, mercury is the cathode in electrical industry, graphite gaskets, telephone parts, TV picture tube coating.

　　3, Graphite can be used as a wear-resistant material: Graphite in the mechanical industry often as a lubricant. Lubricating oil is often not used in high speed, high temperature and high pressure, while the graphite wear resistant material can be used in the temperature of the 200~2000 (a) at a very high speed, without lubricating oil. Many devices for conveying corrosive media are widely used in the piston cup, sealing rings and bearings, which do not need to be added to the lubricating oil. Shi Moru is one of many metal processing (drawing, drawing) the good lubricant.

　　4, graphite has good chemical stability. After special processing of graphite, with corrosion resistance, good thermal conductivity, low permeability characteristics, which is widely used in the manufacturing of heat exchanger, reaction tank, condenser, the burning tower, absorption tower, a cooler, a heater, a filter and pump equipment. Widely used in petrochemical, wet metallurgy, acid alkali production, synthetic fiber, paper and other industrial sectors, can save a lot of metal materials.

　　5, Graphite can be used casting, foundry, molding and high temperature metallurgical material: due to graphite thermal expansion coefficient is small, and the capability of rapid quench heat changes, as the mold of the glass, the use of graphite black metal by casting, precise size, smooth surface and high rate of finished products, processed or minor processing can be used, thus saving a large amount of metal. Production of hard alloy and other powder metallurgy process, usually made of graphite materials and sintered in the use of the porcelain boat. The crystal growth crucible, the area of the refining container, the support fixture, the induction heater and so on are all made of high purity graphite. Graphite can also be used for vacuum smelting of graphite heat insulation board and base, high temperature resistance furnace tube, rod, plate, grid and other components.

　　6, Graphite can be used in the atomic energy industry and defense industry: graphite has a good neutron reducer for the atomic reactor, uranium graphite reactor is currently used more of an atomic reactor. As the power of the atomic energy reactor in the reduction material should have a high melting point, stability, corrosion resistance, graphite can meet the above requirements. As the graphite purity of the nuclear reactor is very high, the impurity content should not exceed several tens of ppm. In particular, the boron content should be less than 0.5ppm. In the defense industry, the use of graphite to produce a solid fuel rocket nozzle, a missile nose cone, the space navigation equipment parts, heat insulation materials and ray material.

　　7, graphite can prevent the boiler fouling, the unit test shows that adding a certain amount of graphite powder in the water (about 4~5 grams per ton) can prevent the boiler surface fouling. In addition graphite coated metal chimney, roof, bridge, pipeline can be anti-corrosion.

　　8, graphite can be used as pencil core, pigment, polishing agent. Graphite after special processing, can produce a variety of special materials for the industrial sector.

Graphite is a very good lubricant, and sometimes to graphite with Vaseline or motor oil are mixed together to form graphite lubricant, it can be used to replace oil lubricants operating in high temperature parts of the machine. Graphite lubricant is mainly iron and steel enterprises rolling machine with an important process of material consumption, the mandrel is in more than 900 degrees high temperature steel tube and withstand high rolling pressure state during to large relative sliding and steel pipe and high-performance Shi morun slip agent is whether the unit normal production essential factors.

For seamless steel pipe floating, box set, clamping mandrel lubricant for mandrel dairy, holding the patent technology of graphite, the lowest friction coefficient, good adhesion, off the stick performance good, soluble, good stability, application of solid low, the viscosity is 40 to 70 seconds.

Graphite lubricant, the lubricant is composed of graphite powder, sodium silicate, sodium silicate, sodium silicate, sodium silicate, and surfactant, wherein the weight of the lubricant is accounted for by 60-85%, the weight of the sodium silicate which accounts for 4-10%, the weight of the sodium silicate, and the weight of the surface active agent accounted for 0.2-1.5. According to the present invention and the existing technology, the high temperature lubrication characteristics of the lubricant are improved, and the wetting, spreading and emulsifying properties of the medium are improved.

　　Graphite powder is a chemical reaction is very sensitive material, in the different environment inside his resistivity will change, his resistance values will change, but is not the, graphite powder is one of non metal conductive material is very good.

　　Because of its special structure, graphite has special properties:

　　1) high temperature resistant: Graphite melting point of 3850 + 50 DEG C, the boiling point of 42.5 DEG C, even the ultra high temperature arc ignition, weight loss is very small, coefficient of thermal expansion is also very small. Graphite strength increases with temperature, and the intensity of graphite is increased by one time at 2000.

　　2) the conductivity of graphite is one hundred times higher than that of general non metallic mineral. Thermal conductivity over steel, iron, lead and other metal materials. The thermal conductivity decreases with the increase of temperature, even in high temperature, graphite as insulator.

　　3) the lubrication performance of graphite is determined by the size of graphite flake, the bigger the scale, the smaller the friction coefficient, the better the lubrication performance.

　　4) chemical stability: graphite has good chemical stability at room temperature, acid, alkali and corrosion resistance to organic solvents.

　　5) plasticity: the toughness of the graphite is good, can be a very thin slice.

　　6) thermal shock resistance: graphite can withstand the temperature of the severe changes in the temperature of the temperature change and not cause damage, when the temperature is changed, the volume of graphite is not big, will not produce cracks

In EDM process, due to EDM parameter selection of inappropriate, or processing chip discharge is not so good reasons to produce concentrated discharge arcing, such as electric sparks are scarce and red sparks, the electric discharge sound has become irregular, then produce the so-called unstable discharge. Processing is not stable, the processing current is not in accordance with the set of the current work, the working current is small, and in the process of processing will appear a variety of processing defects, resulting in waste. Often the following abnormal discharge phenomenon.

　　(1) the discharge is not stable at the start of the process

　　At the beginning of the processing of graphite electrode, due to the workpiece being chip cutting, burr, resulting in concentrated discharge; and due to the discharge energy (high peak current, pulse width), and pulse interval is too narrow, jet pressure is too large, resulting in at the beginning of processing discharge instability. Therefore, the machining process of the first complete removal of the workpiece on the workpiece, burr, and the removal of heat treatment due to the oxide film, paint, rust, etc.. At the start, the current is set at a small value, and then gradually increased to the peak current, and the jet pressure is set to a small number of.

　　(2) a granular projection

　　In the process of electric spark machining of graphite electrode, the machining depth is too deep to produce electric arc, and the granular material is formed on the workpiece, which causes the workpiece to be scrapped (as shown in Figure 1).

　　Cause of:

　　Pulse width is set too large, the angle of the edge of the electrode to generate granular protuberance, thus causing short circuit, causing arcing; electric corrosion product processing chip too much, will not be drained; processing liquid nozzle angle setting is wrong, the machining liquid can not be fully spray into the gap, electric corrosion product processing chip can not be fully discharged; processing depth, processing chips can not be fully discharged, stranded at the bottom.

　　Solution scheme:

　　Shorten the pulse width ton, longer pulse interval toff, inhibit the production of granular protrusion on the generation and electric corrosion product processing chip, and as far as possible to the side of the nozzle is arranged on the electrode; if the processing depth and improve the number of vibrations of the electrode and to accelerate the speed of vibration.

　　(3) machining of the ground

　　In EDM process and pulse interval is too small, the electrode vibration speed slow, jet pressure is weak, resulting in electric corrosion product processing chips can not be fully discharged and many electric corrosion product bonded on the electrode surface, forming carbon block, in the electrode motion of easy detachment, in ground processing produce depression (Figure 2).

　　Solution:

　　Extend the pulse interval, improve the electrode vibration velocity, jet pressure increases, also can in the process to suspend processing, with a brush cleaning electrode surface and processing the bottom surface of the processing chip.

　　(4) the entrance space is large

　　Because of the graphite electrode lifting speed is too slow, at the lower end of the processing time is too long, the absolute loss, and at the entrance to the electrode of the discharge gap exist electric corrosion product, resulting in "secondary discharge" (machined surface due to the involvement of electrical corrosion products such as again for unnecessary discharge), the discharge gap to expand, in the depth direction of processing produce processing angle, entrance space (as shown in Figure 3). Therefore, in the process of processing, the graphite electrode can not be too slow.

　　(5) the process of machining the bottom surface or the bottom surface roughness is not uniform

　　Due to the pulse interval is too small, especially jet pressure uneven, inter electrode gap is too small, electrical corrosion products can not fully discharged, and at the bottom of the machining surface is not uniformly distributed, so along with the processing continuously, on the bottom surface bending (as shown in Figure 4 (a)) or cause at the end of processing rough surface is not uniform (as shown in Figure 4 (b) below).

　　Solution:

　　Increasing the pulse interval, setting the constant jet pressure, increasing the gap between the two electrodes, often check the chip removal.

　Characteristics of graphite

　　1 light weight: the proportion of 1/5, copper, suitable for the production of large electrodes

　　2 machine processing performance is good: cutting resistance for copper 1/3

　　3 surface easy to deal with: no burr after machining, easy manual processing

　　4 high temperature: when the temperature reached 3650 degrees Celsius, it can withstand higher current.

　　5 the thermal expansion coefficient is low: 1/4 for copper, and the heat is not deformed

　　6 discharge machining speed: discharge machining speed than copper block 3~5 times, large area or rough machining more obvious.

　　7 electrode loss is small: the ratio of the copper and copper is 2:4, it can be processed without damage.

　　Machining method of graphite electrode:

　　1 tool requirements: sharp, there is a large front and rear corner and the capacity of the chip

　　2 tool material: carbide knife coating knife

　　3 feed speed: 5500~8000 roughing finishing 4000~6000

　　4 machine speed: rough machining 6500~10000 turn; finishing 6000~20000 turn

　　5 processing margin: rough machining 0.6mm; finishing 0.3mm

　　6 cutting capacity: the amount of lateral cutting is 1/2~2/3, and the depth of cutting is 1~1.5 times of the diameter of the cutter.

　　7 cutting direction: the direction of the cutting is better than that of the cutting, and the milling is better than the reverse.

　　CNC machining speed, cutting, easy dressing: high speed milling rough machining a copper block 3 times, high speed milling finishing a copper block 5 times, and its strength is very high, for high (50-90mm) ultrathin (0.2 0.5 mm) of the electrode, processing is not easy to deform. Many times the product needs to have good ruled surface effect, which requires to do the whole of the electrode and in the production of the whole electrode exists all sorts of hidden corner cleaning, due to the characteristics of graphite is easy to repair, making this problem is easy to solve, and greatly reduce the electrode number, can realize the complex geometry, and copper is unable to do so

　　Rapid EDM molding, thermal expansion is small, low loss: because the conductivity of the graphite is better than copper, so it is faster than the rate of copper, copper, 3-5 times. And the discharge can withstand the larger current, electric spark rough machining more favorable. At the same time, under the same volume, the graphite weight is 1/5 times of copper, which greatly reduces the load of EDM. For the production of large electrodes, the overall electrode has a great advantage. The sublimation temperature of graphite is 4200 for copper 3-4 times (the sublimation temperature of copper is 1100). At high temperature, the deformation is very small (under the same electrical conditions for copper 1/3-1/5) is not softened. Can be efficient, low consumption of the discharge energy transfer to the workpiece. Because of the high temperature strength of graphite, the discharge loss (1/4) can be reduced effectively, and the quality of the process can be ensured.

　　Light weight, low cost, production costs for a set of mold, electrode CNC machining time, EDM, electrode wear accounted for overall body most, and these are determined by the electrode material itself. Graphite and copper are compared, the machining speed and CDM speed of graphite are 3-5 times of copper. At the same time, the characteristics of wear minimum and the overall graphite production, can reduce the number of electrodes, but also reduces the electrode material and machining time. All of these can reduce the production cost of the mold.

　　How to use graphite materials and other relevant factors to consider is, of course, die by the copper electrode conversion of graphite electrode. First of all, should be clear. Today part of the spark machine customers using graphite electrode discharge machining, which eliminates the mold cavity polishing and chemical polishing process can still achieve the desired surface finish. Without increasing the time and polishing process, the copper electrode can not produce such a workpiece. In addition, graphite is divided into different levels, in a specific application using the appropriate levels of graphite and electric spark discharge parameters to achieve the ideal processing effect, if the graphite electrode spark machine uses the operating personnel and the copper electrode of the same parameters, then the result would is disappointing. If you want to strictly control the electrode material, the graphite electrode can be used in the rough machining non loss state (loss of less than 1%), but the copper electrode is not used.

　　1. The increasing complexity of the mold geometry and the diversification of product applications require more and more high discharge accuracy of the EDM machine. The graphite electrode has the advantages of easy processing, high removal rate and low loss of graphite. Therefore, some of the spark machine customers have abandoned the copper electrode and switched to the graphite electrode. Also some special shape electrode cannot be made of copper, but graphite is easy molding and copper electrode is heavy, not suitable for the processing of large electrode, these factors caused part of the spark client application of graphite electrode.

　　2.Graphite electrode is easy to process, and the processing speed is significantly faster than the copper electrode. For example, the use of the milling process of graphite, the processing speed is 2 ~ 3 times faster than other metal processing, and no additional manual processing, and copper electrodes need to be put on the ground. Similarly, if the use of high speed graphite machining center manufacturing electrode, the speed will be faster, more efficient, it will not produce dust. In these processes, the selection of suitable tools and graphite can reduce the wear and tear of the cutting tool. If more specific milling time of the graphite electrode and the copper electrode and graphite electrode, graphite compared to copper electrode fast 67%, in general electrical discharge machining by graphite electrode machining than the copper electrode fast 58%. As a result, the processing time is greatly reduced, but also reduces manufacturing costs.

　　3.The graphite electrode and the traditional copper electrode design. Many die companies usually in copper electrode of rough machining and finish machining have different amount of reserve, and graphite electrode is used almost the same amount of reserved. This reduces the number of CAD / CAM and machine processing, for this reason alone is sufficient to improve the accuracy of the mold cavity in a large extent.

　　Graphite is a super material of chemical industry, the chemical stability of the very prominent, acid and alkali resistance, corrosion resistance, in the chemical industry has a special position.

　　Natural graphite with bulk graphite and flake graphite is the best, the most widely used. I haven't found massive blocky Graphite Deposit, flake graphite and aphanitic graphite has a large deposit, and formed a large-scale mining base.

　　Natural graphite has many excellent properties, so it is widely used in various sectors of the national economy, especially in the metallurgical, mechanical, electrical, chemical industry has been widely used.

　　Graphite has outstanding resistance to high temperature and low temperature resistance properties, a small expansion coefficient, volume stability, so it can anti quench heat changes, the graphite resistance high temperature properties and general metal different when the temperature rises, it is not tend to soften, and its strength instead of increased.

　　Graphite is a good conductor of heat and electricity, similar to how the heat transfer performance and conductive performance and most metals, but also its characteristics, general metal when the temperature increases, thermal conductivity increased, and the thermal conductivity of graphite on the contrary, at elevated temperature, the thermal conductivity instead. At extremely high temperatures, the graphite tends to be insulated, and thus, in the case of high temperature, graphite Heat insulation performance is very reliable.

　　Graphite plasticity and lubrication has been obtained in industry, larger scales, friction coefficient is small, so graphite flake is the most slippery, lubrication best, dense crystalline graphite times, earthy graphite lubricant is poor.

　　Graphite or atomic reactor excellent moderator, the use of graphite has entered a new historical stage, in order to manufacture excellent retarding agent, graphite purification process was further developed, so graphite has become important materials in atomic energy industry.

　　Because of its special structure, graphite has special properties

　　1) high temperature resistant: Graphite melting point of 3850 + 50 DEG C, the boiling point of 42.5 DEG C, even the ultra high temperature arc ignition, weight loss is very small, coefficient of thermal expansion is also very small. Graphite strength increases with temperature, and the intensity of graphite is increased by one time at 2000.

　　2) the conductivity of graphite is one hundred times higher than that of general non metallic mineral. Thermal conductivity over steel, iron, lead and other metal materials. The thermal conductivity decreases with the increase of temperature, even in high temperature, graphite as insulator.

　　3) the lubrication performance of graphite is determined by the size of graphite flake, the bigger the scale, the smaller the friction coefficient, the better the lubrication performance.

　　4) chemical stability: graphite has good chemical stability at room temperature, acid, alkali and corrosion resistance to organic solvents.

　　5) plasticity: the toughness of the graphite is good, can be a very thin slice.

　　6) thermal shock resistance: graphite can withstand the temperature of the severe changes in the temperature of the temperature change and not cause damage, when the temperature is changed, the volume of graphite is not big, will not produce cracks.

　The technological properties of graphite are mainly determined by its crystalline form. Crystalline morphology of different graphite minerals, with different industrial value and purpose. Industry, according to different crystalline morphology, the natural graphite into three categories.

　　1.dense crystalline graphite

　　Dense crystalline graphite is also called bulk graphite. Such graphite crystal clear crystal visible. Particle diameter greater than 0.1 mm. The crystal arrangement is disordered and the structure is compact and massive. This: the characteristics of graphite is high grade, general carbon content is 60 ~ 65%, sometimes up to 80 ~ 98%, but plasticity and smooth than that of flake graphite.

　　2.flake graphite

　　Graphite crystals are in the form of a scale; this is made of high strength under high pressure. This kind of graphite ore is characterized by high grade, generally in the 2 to 3%, or 100 to 25%. Is one of the best ore floatability in nature, which can take over HISTEP grade graphite concentrate. This type of graphite can be floating, lubricating, and more malleable than other types of graphite; therefore, it is the largest industrial value.

　　3.aphanitic graphite

　　Hidden quality graphite also known as amorphous or soil shaped graphite, the graphite crystal diameter, generally less than 1 micron, is a collection of microcrystalline graphite, only under the electron microscopy can be seen in the crystal. The characteristics of this kind of graphite is that the surface is ground, lack of luster, and poor lubrication. Higher grade. General 60 ~ 80%. A few more than 90%. Ore optional sex is poor.