Bulk Synthetic Graphite
Bulk synthetic graphite is used for a wide variety of industrial applications. It is a unique high-temperature material with great conductive properties for both thermal and electrical applications. Graphite does not melt when heated (above 1,500 degrees C) but it does oxidize. Graphite requires petroleum coke for the manufacture and typically requires several weeks to process, which typically includes pressing, baking and graphitization.
Graphite applications include: electric arc furnace electrodes; electric motor brushes; lubricants; refractories; casting molds; friction materials and electrical discharge machining (EDM) electrodes.
What are the characteristics of synthetic graphite?
Synthetic graphite properties include both metal and a non-metal. It is semi-flexible but not elastic, and is highly refractory and chemically inert. Graphite has a low absorption of X-rays and neutrons, making it a particularly useful material in nuclear applications.
What are the basic properties associated with synthetic graphite?
Synthetic Graphite Properties:
If bulk graphite is recommended for my application, what questions should I be asking?
The first question should be: "Does your application require extruded or isotropically pressed graphite?"
Extruded graphite characteristics include: uni-directional grain orientation, large particle size, low density and relative low strength values.
Isotropic graphite has no primary grain direction, smaller particle sizes and higher density/strength values.
When used for EDM applications, what graphite grade do most companies prefer?
This is no single grade preferred. Many companies use a less expensive grade for the majority of their work then switch to a more expensive grade for detailed work such as ribs and gussets in a mold or forging die. Other companies use a medium-priced graphite for all of their work. I been told by several EDM Managers that the newer machines with advanced controls are much more adaptable to a variety of materials as the machine control actually adjusts settings based on the results of each spark within the EDM process. Below is a classification of EDM grades by particle size.
How is EDM grade graphite categorized?
Typical users compare graphite particle size and density as the primary indicators for this choice of materials. Larger particle size grades are less expensive and typically used for achieving the highest work piece removal rates. Smaller particle size materials with a higher density are used for the EDM of work pieces that require intricate detail and specific surface finishes.
How can I compare one grade of EDM graphite to another?
Asking the distributor for their material specifications is a good place to begin. Often the distributor's specifications can be compared to that of the manufacturers. If specifications are not offered, ask them why not?
Next we recommend comparative actual test cutting in your EDM. Typically, some simple sharp corner wear and material removal rate tests to varying depths typical of your work will provide valuable information. Use of a CMM, optical comparator or microscope will often give more definitive detail of material wear for comparison.
What percentage of small and medium size tool shops use quick change tooling (manual or with a tool changer)?
We posed this question to a well-known Mid-west quick change tooling vendor a few months ago. His guess was that less than 50 percent of all tool shops use quick change tooling for their EDM applications.
What are my options for disposal of my scrap graphite pieces and used EDM electrodes?
"Clean" scrap graphite, meaning pieces not yet used within the EDM process with no other contamination, is purchased by a few companies within the U.S. Typically, they require 1,000 lbs. or more to defer transportation costs. These pieces can be recycled into a powder form and used for other industrial needs. To our knowledge, graphite used within the EDM process is not recyclable and must be disposed of as industrial waste.
Are the new EDM machines with advanced controls significantly more efficient when compared to the older machines?
The EDM machine sellers are a much better source for this type of information. However, we recently viewed some comparative wear and material removal rate tests inside a large injection mold builder. The minimal electrode wear and material removal rates on a multi-fork shaped electrode after testing were impressive. New advanced machine control features to improve efficiency are now being announced annually by most EDM manufacturers.
How can I receive more specific information regarding my graphite-related needs?
Our Graphite Specialists are available Monday through Friday from 8:00AM to 5:00PM (EST) by calling toll free (800)448-8887. You can also email your question to firstname.lastname@example.org or receive "Live Chat" support online by clicking the link at the top right corner of this page.