PCD tool or CVD diamond coated tool, which is better for graphite machining?

Graphite electrodes offer several advantages when machined. However, machining graphite can be challenging due to its high hardness, which results in rapid tool wear. This post discusses the difference between PCD and CVD cutting tools in machining graphite electrodes.

Diamond coated cutting tools

PCD cutting inserts

PCD cutting tools

Graphite electrodes offer several advantages when machined. They have a low density and can be easily manufactured into large sizes. Additionally, they have a cutting resistance that is only 20% of copper and can be processed at high speeds, which greatly improves the delivery speed and competitiveness of mold enterprises. Graphite electrodes also have low resistance and are conducive to improving the machining efficiency of EDM. Surface of graphite can be machined easily, leaving no machining burrs. Furthermore, graphite materials have high temperature resistance and good thermal stability. Due to these features, graphite electrodes are increasingly being used in mold manufacturing and are gradually replacing copper electrodes.

However, machining graphite can be challenging due to its high hardness, which results in rapid tool wear. Ordinary carbide tools and TiN coated tools can’t even complete a single workpiece without changing the tool when machining graphite products. Although high-quality PCD tools have the hardness of CVD pure diamond coated tools, they can only be made into simple and regular shapes, and can’t meet the machining requirements of complex profile molds.

CVD diamond coated tools are the ideal choice for graphite machining, and their life can reach 10-50 times that of carbide tools. The machining speed of the CVD tool is also 2-3 times higher than that of carbide tools, and there is no need for coolant. Moreover, the thin-wall and deep rib parts of the graphite electrode can be accurately machined. Unlike PCD tools, CVD tools can grow a pure diamond coating on a tool substrate of any geometric shape, making them suitable for machining complex contours.

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