The graphite electrode has the advantages of easy processing, high metal removal rate in EDM, as well as a small loss of graphite. Therefore, more and more mold factory abandon the use of copper electrode and choose graphite electrode. So, what are the advantages of graphite?
1).The proportion of graphite is copper 1/5, the weight of the same volume of graphite is 5 times lighter than that of copper. the large electrodes made from copper are too heavy, in the long running, it is very unfavorable to the accuracy of the machine tool spindle on the EDM. But graphite is opposite and in safe handling!
2).The graphite can have a very high processing speed, the general speed of the processing of graphite is 3-5 times faster than the ordinary metal. And it can reduce tool wear and electrode loss when we choose suitable hardness tool and graphite,.
3).The graphite is easy to shape and will not be deformed, and some of the shape of the electrode with copper is not easy to make and can be easily achieved with graphite. Such as thin slice electrode, the copper deformed easily in machine processing and EDM. But graphite can easily reach and graphite in EDM can with larger current and processing speed, we don't worry about that deformation because of the high temperature and the workpiece is damaged.
4).The finishing and polishing of graphite, in general, the graphite after the processing do not need to be polished. It also reduces the precision error of the graphite electrode after forming and shortens the production cycle.
5).The EDM speed of graphite is quick and losss is mall because the melting point of copper is 1083 degrees Celsius, while the temperature of EDM at 1100 C, the copper electrode in the EDM is relatively easy to consume and wear. And the graphite in 3550 degrees will appear sublimation, as long as the proper processing parameters, graphite electrode can achieve the theoretical significance of the zero loss. So as to avoid the number of electrode processing.
6).In the design and programming of electrode, graphite electrode design is also different. Many mold factory usually reserved in different copper electrode roughing and finishing, and the graphite electrode can be used for the same amount, which reduces the number of workload and machine CAD/CAM. For this reason alone is enough to reduce the mold design and processing cycle, but also reduce the probability of error processing.

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.

           Using graphite as electronic conductor material of the electrode.Graphite chemical properties is stable, low overpotential of chlorine, good mechanical strength, easy processing, price moderate.Is widely used in industry, such as used in dry cells positive electrode collector body (graphite rod), industrial electrolytic cell anode, etc.Of chlor-alkali industry in the early, chloride with graphite electrode material, but the drop of slag after chlorine corrosion such as chip jams diaphragm is easy to cause short circuit, shorten the life of electrolyzer, is gradually replaced by titanium form stable anode.In the lab is also commonly used as a price lower inert electrodes.

　　The graphite used discharge loss smaller;Because the spark oil also contains C atoms, in electro discharge machining, the C atoms are deliquescence in low temperature lead to spark oil, instead of care for membrane, the outline of the graphite electrode made up for the loss of graphite electrode.

　　Other, graphite or light property of glass and paper polishing agent and anti-rust agent, is to build a pencil, ink, black paint, printing ink and natural diamond, diamond no shortage of raw materials.It is a very good energy conservation and environmental protection material, the United States has used it as a car battery.As the best contemporary science technology and industry, expand the application range of the graphite in endless, has become a high-tech new composite material demand to the scope of the raw material, in oh economy has the need to see.the lighter weight: the density of graphite only 1/5 of copper, large electrode in EDM, effective low machine tools (EDM) tired of falling;The use of more right in in the large mould.

　　Material is less simple deformation: in thin steel electrode processing on the upper hand clearly;The softening point of copper in 1000 degrees, simple deformation because of the heat;The sublimation of graphite temperature is 3650 degrees;1/30 of the thermal expansion coefficient of the copper. wear-resistant lubricating material: graphite as smooth agent in mechanical property.Smooth oil often means less than on the premise of high speed, low temperature, low pressure, and graphite can wear resistant materials in 200 ~ 2000 ℃ temperature under high sliding velocity, not oil.Many walks of oxidation medium equipment, throughout the adoption of graphite material made from the piston cup, seal and bearing, no need to join when they run smooth oil.Graphite is a lot of metal processing (wiredrawing, laguan) good lubricant.

　　New application of graphiteas a conductive material: on the electrical property is used as electrode, carbon brush, rods, tubes, the anode, to the mercury is graphite gaskets, mobile phone parts, television tube coating, etc. the processing speed faster: usually environment, graphite the machine rate of 2 ~ 5 times faster than copper.The discharge processing speed is faster than copper 2 ~ 3 times;

　　So, it is a kind of ambition sealing material.Popularity is used to heat the oil chemical industry, atomic energy and other belongings.The international market demand is increasing year by year.as refractory material: graphite and its products have the essence of the low temperature resistance, high strength, the first is used to produce graphite crucible in the metallurgical property, the graphite is commonly used in steelmaking for ingot protectant, metallurgical furnace lining. Graphite pencil lead, pigment, polishing agent.Graphite through special processing, can make all kinds of uncommon material used for the fortune some.

　　For atomic energy wealth and possessions of defense: graphite is good neutron moderator for atomic reaction in the heap, a uranium graphite feedback heap is used more of an atomic pile response.As power with slow data in a nuclear reactor should have high melting point, the stability, resistance to oxidation of defiance, graphite can completely meet the above requirement.As feedback atomic pile with graphite requires high purity, impurity content should not across dozens of PPM.Rated a boron content should be less than 0.5 parts per million.Also used in the defense of property of graphite produce solid rocket nozzle, missile nose cones, space travel is equipped with the machine, heat insulation material and the ray material.9, electrode, graphite can somehow replace copper as electrode?don't have a burr;Copper electrode in the processing is completed, still need to manually trim to remove burrs, and no burr after graphite processing, save a little ready cash, at the same time are easier to implement positive change production;graphite has good chemical stability.Graphite by uncommon processing, has the oxidation resistance, good thermal conductivity, seeping into the elementary characteristics of seepage rate, small amount used to produce heat interchanger, reaction tank, condensation, ignition, attract towers, cooler, heater, filter, pump facilities.Widely applied to heat the oil chemical industry, hydrometallurgy, acid and alkali production, synthetic fiber, paper and other part of fortune can be so much the amount of metal materials.

Graphite electrodes material are characterized by superior compact structure, good electrical and thermal conductivity, high resistance to oxidation and corrosion in high temperature. The regular power graphite electrodes graphite electrodes for heavy industrial arc furnaces, steel mills, foundries, and other applications.

　　There are a lot of selection criteria for graphite electrode material, but the main selection criteria are four.

　　1.Average particle diameter of graphite electrode materials

　　Average particle diameter of graphite electrode materials Direct influence on the discharge of materials。The smaller the average particle size of the graphite electrode material, the more uniform the discharge of the material, the more stable the discharge, the better the quality of the surface.。For the surface machining accuracy of the casting die casting die, recommend the use of coarse particles of material， For the higher accuracy of the processing of the electronic mold, recommended the use of smaller particles of the material, in order to ensure the accuracy of the processing mold, surface finish。The smaller the average particle size, the smaller the loss of the material in the process.。

　　2.Flexural strength of graphite electrode materials

　　The flexural strength of the graphite electrode material is the direct embodiment of the material strength. Show close degree of internal structure

　　3.Shore hardness of graphite electrode materials

　　In the subconscious of the general people, graphite is considered to be a kind of strength of the material, but in the actual measurement data and application show that the strength of graphite, higher than the metal material。

　　4.Intrinsic resistivity of graphite electrode materials

　　If the average particle size of the graphite electrode material is the same, the resistivity of the electrode material is slower than the resistivity of the material. For the same average particle size of the electrode material, the resistivity of the material, its strength and hardness will be corresponding to the resistivity of the graphite electrode material. Discharge speed, loss will be different, so according to the actual application of the need to choose the appropriate material is very important.

　　These four kinds of data represent the main discharge performance of the material, and directly determine the performance of the material.

　　　　Graphite Electrode is mainly usded for steel-making in electric furnace,mineral hot furnace and electric resistance furnace.Graphite electrode conducts electric current into the furnace.Electric current produces arc in the smelting district in the electric furnace,when the temperature increase to about 2000℃,smelting begins.Our a series of graphite electrode is applicable to the common furnace and high power furnace with high pressure and short arc.

　　The graphite electrode must be stored in a clean and dry room. If the graphite electrode is pilled up outdoor, it must be covered with the waterproof cloth and the floors of the pile is prohibited more than 4. In the delivery of graphite electrodes, a waterproof cloth must be covered on the graphite electrodes. When workers are delivering and pilling up graphite electrodes by forklift, collision is prohibited. Only one floor is allowed put each time, and the workers must pay more attention to the balance of the graphite electrodes, it can avoid the graphite electrodes sliding and broken

　　When loading and unloading the graphite electrodes by crane, a steel wire must be used as assistant tool. Hooking the bend of the package directly is prohibited. Before using the graphite electrodes, they need to dry near the electric furnace, the temperature should not exceed 150℃,the time should beyond 24 hours. When using the graphite electrodes, the workers must nip the steel bend by special tool, not by forklift.

　　In the use of graphite electrodes , Clean open socket with compressed air, Screw nipple into socket carefully, not to damage threads. Bring down upper graphite electrode until opening between two electrode becomes 20 to 30mm. Clean out opening between graphite electrodes with compressed air. To avoid the graphite electrode breakage, remove any nonelectro conductive material from furnace. To avoid graphite electrode breakage be sure to place large scrap at furnace bottom and small scrap at top. Graphite electrodes should be stored in dry and clean place. To avoid shock and collision . Be sure to dry them up before use. Please feel free to contact us for the inquiry or demand of the graphite electrodes.