The physical properties of each grade of graphite determine the ranking within classifications. The properties that influence performance are particle size, flexural strength and shore hardness. These properties along with a photomicrograph of the microstructure are the best tools for predicting graphite performance. […]
The graphite industry is constantly striving to produce higher quality grades. Graphite materials have continued to evolve along with the other aspects of the EDM industry, but at a less dramatic pace. Advancements have been made in the microstructure of the graphite materials, as this is the key to performance. […]
Graphite selection is critical to the success of the job. It is important to understand the characteristics and physical properties of the different manufactured brands and grades produced. The various grades should fall within one of the four EDM classifications: Angstrofine – Less than one-micron particle size material is used when extremely fine surface finishes [...]
The machined, natural EDM finish is the surface that the EDM process leaves on the metal at the end of the finishing cycle. The finishing cycle puts the most stress on the graphite electrode. Finish settings are high frequency cycles with more sparks, or discharges, per second due to the short on and off times [...]
A mold with a good EDM finish is ready to use right out of the machine (tank-to-part technology), while a mold that needs to be etched or polished to get the desired finish requires extra steps that increase cost and extend production time. […]
Graphite is a highly abrasive material, and tends to wear out cutters quickly. One of the greatest difficulties encountered when machining graphite is that cutter wear can reach unacceptable levels within the time required to machine a single, multi-featured electrode. As such, advanced tool coatings offer a significant benefit when producing graphite components. [...]
The advantages of laser engraving are described below: […]
Disposable inserts with a 1/64- to 1/32-inch nose radius are most effectively employed for turning graphite. A positive rake insert without a chip control groove is preferred. Cutting fluids and/or coolants are not recommended. Adequate and well-maintained fixturing, rigid tool setup and well-adjusted machine tools always provide superior results. […]
Most information for turning graphite applies to milling with inserted cutters. Disposable inserts with a 1/64″ or 1/32″ nose radius are most effectively employed for milling graphite. A positive rake insert is recommended. Cutting fluids and/or coolants are not recommended. Adequate and well-maintained fixturing, rigid tool set-up and well-adjusted machine tools always provide superior results. [...]
The same general practices of machine tool maintenance, fixturing and rigidity of tool setup recommended for turning apply equally well for milling. Short tool extensions and properly adjusted machine tools are essential to good performance. […]