Discover EDM-C3^® Premium Copper-Impregnated Graphite

In a previous discussion, we examined EDM-AF5^®, a reliable graphite grade known for its balanced performance in electrical discharge machining (EDM). For applications requiring fine detail, challenging workpiece materials, and demanding machining conditions, EDM-C3^® offers  another level of capability.

Entegris POCO Materials EDM-C3 is a premium ultrafine, copper-impregnated graphite grade designed to address two common EDM challenges: maintaining electrode integrity at small feature sizes and maximizing machining efficiency in difficult scenarios. The result is a graphite grade engineered for reliability, strength, durability, and efficient energy transfer under less-than-ideal conditions.  EDM-C3 is widely considered the industry standard for copper impregnated-electrode materials.

What Makes EDM-C3 Different?

EDM-C3’s structure provides a unique blend of mechanical strength and EDM performance, combining ultrafine (<5 µm) particles that support precise machining of intricate electrode geometries with copper impregnation throughout the graphite matrix which lowers resistivity to 127 µΩ-in. This enables EDM-C3 to achieve more efficient energy transfer than non-infiltrated ultrafine grades, which typically range from 500 to 800 µΩ-in.

Its lower resistivity, in turn, directly improves EDM performance, especially when machining subprime metals, carbide, or aerospace alloys. Increased strength and damage resistance also help prevent edge chipping and breakage during electrode fabrication and use, making EDM-C3 ideal for threading electrodes, thin cross sections, and other precision applications where electrode failure can quickly become costly.

EDM-C3 is available in a variety of forms—including billets, semi-finished rods, blocks, and plates—allowing manufacturers to select the starting geometry that best aligns with their fabrication workflow.

Performance Metrics and Grade Comparison

From a mechanical standpoint, EDM-C3 stands out among ultrafine graphite grades. It offers a flexural strength of 20,300 psi and a compressive strength of 28,350 psi—the highest in its class. A hardness rating of 66 Shore further supports precision machining without excessive wear or brittleness.

EDM-C3 shares the same particle size to EDM-3, but offers a higher strength, as noted above. The copper impregnation further differentiates EDM-C3 by dramatically improving electrical conductivity, thereby enhancing machining efficiency even in suboptimal workpiece materials and machining conditions. 

Selecting the Right Electrode Material

Selecting electrode material for EDM involves balancing key criteria: work metal type, electrode detail and strength, EDM performance, cost, and physical characteristics. Its versatility makes EDM-C3 effective across a broad range of difficult-to-machine metals. High flexural and compressive strength enable durable, fine-featured electrodes. Copper impregnation ensures efficient energy output and fast machining for reliable performance under demanding conditions, while reduced fabrication time and electrode wear help reduce total job cost—even if the upfront material cost is higher than for standard grades. Finally, its exceptional strength supports delicate geometries, and its hardness and microstructure maintain precision and surface finish with no chipping.

Partner with Entegris POCO Materials

EDM-C3 exemplifies Entegris POCO Materials dedication to consistency, performance, and application-focused material development. For manufacturers assessing electrode materials for demanding EDM applications, the next step is to contact an EDM applications specialist, review detailed grade charts and technical data, or connect with a local distributor via the company’s EDM distributor network.

Choosing the right graphite grade can be the difference between acceptable results and optimal performance — and EDM-C3 is built for cases where that difference counts most. To get started  working with us:

• Reach out to an applications specialist for tailored guidance

• Review grade charts and technical documentation

• Locate and contact distributors via their EDM distributor page