Industry Applications
Application
Graphite Milling Cutter Application Cases
Case Details
Due to their rapid discharge rate, light weight, excellent thermal stability, and ability to be formed into complex geometries, graphite electrodes are increasingly becoming the material of choice for mold-making customers. At the same time, because the properties of graphite and its machining principles differ from those of metals, machining graphite not only places higher demands on cutting tools but also requires significantly different machining strategies compared with conventional copper electrodes. Consequently, achieving efficient machining of graphite electrodes presents a substantial challenge for customers. Nanjing Jianchuan Shi boasts extensive experience in graphite machining, and Jianchuan Shi is committed to helping customers enhance the efficiency of their graphite electrode machining processes, thereby fully leveraging the advantages of graphite electrodes in molds and finished products.
Graphite material
Graphite is a common mineral material and is used in pencils. Powdered graphite has a chemical purity of 99.97% carbon, exhibits high hardness—approaching that of tungsten carbide—and is non-toxic; even extremely fine dust does not spontaneously ignite or cause dust explosions. In addition, it boasts high electrical conductivity and thermal stability, a specific gravity four times lower than copper (making it lightweight), resistance to acids, and non-magnetic properties—features that also make it suitable for use as an electrode. There are seven graphite producers worldwide, each offering six grades, for a total of approximately 50 different grades. The particle size of graphite determines the characteristics of each grade.
Principles of Graphite Machining
Unlike metal cutting, which induces plastic deformation in the workpiece, graphite machining operates by using the cutting tool to impart impact forces that initiate and propagate cracks in the graphite material, ultimately leading to chip formation and removal. The cutting forces involved in graphite machining are approximately 10% of those required for machining ductile metals such as aluminum and copper; moreover, due to graphite’s excellent thermal conductivity, cutting temperatures do not pose a significant challenge in this process.
Processing Strategy
Machining strategies for graphite milling are of paramount importance. Even with the same diamond-coated tool and identical cutting parameters, employing different programmed machining strategies can result in tool life differing by several times. Moreover, the right machining strategy can effectively prevent issues such as chipping at the corners of graphite electrodes and improve their surface quality. Graphite electrode milling is closely linked to electrical discharge machining, which means that engineers must not only possess expertise in milling but also have a solid understanding of EDM.
Graphite milling cutter (diamond-coated tool)
It is well known that, due to the high hardness of graphite, diamond-coated end mills are the optimal choice for machining graphite. The coating itself also places stringent requirements on the carbide substrate. Diamond coatings are produced via CVD chemical vapor deposition and represent one of the most challenging coating types; the crystalline structure and elemental composition of carbon within the coating significantly influence its performance.
Application Cases / Demo Parts
1. Face milling
Processing parameters:
VC=565 m/min
fz=0.08
n=30,000 rev/min
vf=4800
ap=0.35mm
ae=3mm
2. Slot milling and contouring machining
VC=565 m/min
fz=0.055
n=30,000 rev/min
vf=3300
ap=2.7mm
ae=6mm
Arrowstone is committed to assisting our customers in developing or optimizing machining solutions for graphite electrodes used in molds. Please contact us if you have any questions.
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