Proven to perform equal to or better than POCO, at a more competitive price. Ships same day for most sizes.
We can supply EDM graphite in rounds and blocks. Send us your sizes and specifications for quotations.
|Average Particle Size (µ)||<4||7||<7||<8||14|
|Flexural Strength (psi)||13,600||12,000||11,500||10,000||7,500|
|Apparent Density (g/cc)||1.85||2.76||1.8||1.78||1.69|
|Electrical Resistivity (µΩin)||520||84||600||600||650|
There has been a lot of discussion over the years about what makes a good EDM graphite. EDMers have learned that is not an easy question to answer. A lot depends on the job to be done. For one, it may be speed, for another, surface finish and for a third, wear resistance. Is it a simple electrode or does it have fine detail or fragile features? Only the EDMer can know that for sure, but when all is said and done EDMers agree, there are five essential performance factors that emerge as universally important. Only the weight of importance given to each will vary from job to job.
The ease with which an electrode can be fabricated will go a long way toward making an EDMer happy, or very unhappy. Not all electrodes have fine detail, but all electrodes can be ruined by a chip or a hidden flaw in the material. The most important physical properties of the graphite effecting machinability are the strength of the material, its hardness, and its density. MICRON’s unique double bonded microstructure gives an additional strength component to the graphite, combining conventional particle-to-particle bonding with our unique bundle-to-bundle bonds. The result is a material capable of holding fine detail, complex geometries and thin ribs with ease. All this is done without the increased hardness typical of many conventional graphites.
Often overlooked when considering the machinability of EDM graphites is the density of the material. Some graphite manufacturers have even abandoned publishing a density specification in their physical property data! It is easy to see why the density of the material is an important factor when considering an EDM graphite. More particles in a given mass means more material to hold a detailed feature in the electrode, and more material to machine away. The density of the material should always be considered when setting speeds and feeds for electrode fabricating equipment.
THE key physical property affecting the speed of a graphite is the average particle size of the material. The larger the particle size, the greater the rate at which metal will be removed from the workpiece. The MICRON “E” grades run the range of modern EDM materials. The Ultra-Premium E-970 at <4 microns particle size, and Premium E-950C and E-940 at <7 microns, combine better than expected metal removal with all the other performance features expected from EDM graphites in these classifications. At the top of the Superfine classification is the E-900, at <8 microns, combining excellent metal removal with all around solid performance for machinability, wear resistance and surface finish. For maximum metal removal, our speed burner E-888, with a particle size of 14 microns, rounds out the Superfine classification.
Electrode wear is the enemy of the EDMer. Wear resistance from your EDM graphite means fewer electrodes, less time and cost in fabrication, and more time in the EDM doing its job! Three physical properties of the graphite impact the wear resistance of the material. These are the micro-structure, the particle size and the density of the graphite. Particle size and density stand to reason. The smaller the electrode particle dislodged, the smaller the impact on the size of the electrode. Similarly, the more particles of graphite in a given area (density) the less the impact when one of those particles is dislodged.
But there’s more to the story! Now the unique double bonded microstructure of the MICRON EDM electrode materials again comes into play. Since the EDM process is a non-contact machining method, we know that electrode wear comes from the EDM process itself, not from the abrasion of tool on workmetal. Wear in the electrode comes from the bonds in the graphite microstructure breaking down. MICRON EDM graphites combine conventional particle-to-particle bonding with their unique bundle-to-bundle bonds, meaning there are two bonds which must be broken before electrode wear occurs. When the single particle-to-particle bonds of conventional graphites break down, that’s it, they’re done! Two bonds really are better than one!
The surface finish which can be achieved by a given EDM graphite is directly related to three important physical properties, the effective particle size, the microstructure and the density. As any EDMer would expect, the smaller the particle size of the graphite, the smoother the expected surface finish on the workmetal. However, with the MICRON EDM electrode materials, that’s not the whole story.
The unique microstructure of the MICRON materials helps provide superior surface finish. The high-density, discreet bundles into which the particles have been engineered helps give the EDMer a finer surface finish than would be expected from the particle size alone. This “effective particle size” from the MICRON materials is usually typical of materials having particles one to two microns smaller than the actual MICRON particles. Since we know particle size effects metal removal rate as well, EDMers can have a faster material with superior surface finish using the MICRON EDM electrode materials.
Many graphite companies will tell you that the cost of the electrode material is insignificant when compared to the overall cost of the job. Who are they trying to fool! In today’s competitive environment every penny counts. If you can get the same or better quality from a product that costs less, you’re throwing money away by not giving it a try. MICRON EDM graphites offer superior performance on all the factors important to EDMers, and at a very competitive price. Better performance, better price? Try it for yourself and you be the judge. Click Contact Us to set up an evaluation in your shop and prove it to yourself where it counts, in YOUR machine.
There are 5 measured physical properties used to evaluate all EDM graphites. These physical properties combine to determine the performance that EDMers can expect from their electrode materials. Here you can read about these properties and how their values impact performance. More importantly, you can also read about the benefits you, as an EDMer, will derive from using graphite that has properties with values in the ranges recommended.
Manufactured graphite is made up of millions of particles of finely milled powder. EDM graphites typically have particle sizes ranging from 1m up to more than 30m. However, EDM quality graphite today would not have a particle size larger than about 20m. The size of the particles has a major impact on at least two characteristics of the job being completed in the EDM process. First, the surface finish that is achieved is dependent upon the effective size of the particles in the electrode material. With all settings the same on your EDM machine, a smaller effective particle size will produce a finer surface finish. Second, a larger particle size will result in a faster Metal Removal Rate (MRR).
This is the primary measure of graphite strength. An EDMer should look for higher flexural strength in graphite, as it typically indicates both good machinability and reduced particle erosion during the discharge phase. Flexural strength is directly related to the particle to particle bonding within the graphite. With bundled technology the EDMer gets a high particle to particle strength, but in addition the bundling process provides high levels of face bonding between the bundles rather than the typical particle/point bonding seen in conventional graphite technology. Thus the ability to withstand higher tool pressures is significantly increased while the incidence of particle erosion is significantly reduced when bundled technology is utilized.
This is a calculation of how much mass or carbon is contained in a given volume of graphite. Most EDM graphites have densities ranging from 1.55 to 1.90g/cc. A higher density graphite has more carbon contained in a given volume. The higher density graphite typically has better bonding between particles. This usually means that higher density graphite will have lower wear rates during the EDM process.
Graphite is usually measured in Shore hardness values. A desired hardness for good machining of graphite is between 60 and 80 Shore. Micron Research graphites fall between 63 and 76 Shore hardness - perfect for machining. There is little or no chipping or cracking due to high loading, and tool wear is kept to a minimum.
Electrical Resistivity (ER) is usually measured but, surprisingly, has little to do with the actual performance within an EDM application. Of note is the fact that higher density graphites have lower ER values. Micron Research’s materials with their high average densities have generally low ER values. This means that Micron Research graphites never have overheating problems, even in the thinnest ribs or sharpest detail.
Finally, a fundamental change in the way graphite is made. Not just an improvement, a fundamental difference in the way the structure of the graphite is engineered! Almost nothing is made today the way it was forty years ago. But graphite was, at least until Dick Sebring, the creator and developer of this new “Bundled Technology” graphite, stepped outside of conventional thinking and said, “Why not?”, and Micron Research’s unique family of EDM graphites was born!
For about as long as there has been a U.S. EDM industry, graphite companies have been locked into a struggle, and a technology, that has driven them toward smaller and more uniform particle size and porosity. Smaller and more uniform particles and porosity meant stronger particle-to-particle bonds in the micro-structure of the graphite, and that meant better machinability and EDM performance. Other graphite companies had taken that conventional technology about as far as it could go, with sub-micron particle size and very uniform porosity. Where could the technology go from there?
Micron Research Corporation has taken the technology of the past and built upon it, taking the foundation of solid particle-to-particle bonding and adding a new bonding dynamic to the structure of the graphite, what we call “Bundled Technology”. Bundled Technology means that our small, uniform particles have been engineered into discreet, higher density bundles, held together by an additional molecular bond, to create a unique EDM graphite electrode material. The result is a stronger, more machinable EDM graphite that offers less wear, better surface finish and faster metal removal in the EDM machine.
EDM Wear Resistance is all about the bonds. Since EDM is a non-contact metal removal method, it is the EDM process itself that breaks the bonds within the graphite which result in EDM electrode wear. The stronger the internal bonds of the material, the more resistant to EDM wear is the material itself. Conventional graphites depend solely upon particle-to-particle bonding for their wear resistance. MICRON EDM graphites build on the foundation of strong particle-to-particle bonds, and then add an additional bonding dynamic, bundled technology. Particles engineered into high-density bundles make for a more wear-resistant graphite because two bonds must be broken instead of one before electrode wear can occur.