All About Carbide: Technical Insights into Cutting Tools

compiled and edited from information from Hannibal Carbide by​ Bernard Martin

Carbide cutting tools have long been at the forefront of machining technology, revolutionizing various industries through their remarkable hardness, heat resistance, and longevity. In this article, we delve into the technical aspects of carbide, exploring the intricacies of the cutting process and the production of these extraordinary tools.

The Cutting Process
To understand the essence of carbide cutting tools, it's essential to comprehend the cutting process itself. At the heart of this process is an intense, concentrated force applied at the cutting edge, effectively separating the metal's individual crystals. This separation results in the creation of a continuous flowing chip, which eventually moves up the cutting tool face until internal stresses cause it to fracture, breaking away as a segmented or discontinuous chip.

​During this process, a substantial amount of heat is generated at the cutting edge. This heat is primarily due to the friction between the tool and the workpiece as the chip is formed and flows along the cutting tool's face. Remarkably, individual carbide grains are so incredibly hard that they do not deform or flow under these intense forces and high temperatures, ensuring the tool's longevity and efficiency.

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CARBIDE PRODUCTION

Carbide's unique properties play a crucial role in chip formation.

​As we magnify the tungsten carbide at 1000X, we see the results of carbide production, which involves controlling parameters such as cobalt binder content and carbide grain size.

C2 Tungsten Carbide High Magnification (1000X)

1. Increasing % Cobalt Binder: The cobalt binder is a major factor in determining carbide's hardness and toughness. Increasing the cobalt content enhances the toughness, enabling the carbide to withstand mechanical shock or impact loads, which are typical during the cutting process.
2. Decreasing Carbide Grain Size: Carbide grain size is another critical parameter. Smaller carbide grains contribute to a more wear-resistant cutting edge. It's a balance, as smaller grains can lead to decreased toughness.

Carbide Technical Specs

The production of carbide tools involves a series of precise steps to achieve the desired physical properties and performance characteristics:

1. Carbide Powder Creation: Metal powders, usually tungsten, and carbon, are heated to extremely high temperatures, exceeding 2800ºF. This process results in the creation of tungsten carbide powder grains that are exceptionally hard and stable at elevated temperatures.
2. Powder Sorting and Mixing: The carbide powders are sorted by grain size and then recombined in appropriate ratios to achieve specific physical properties. Cobalt metal powders are mixed thoroughly with the tungsten powders.
3. High-Pressure Compaction: The tungsten-carbide-cobalt mixture is forced under high pressure (30,000 psi) into molds of the desired shape and size. This forms the initial carbide blanks.
4. Pre-Sintering: Carbide blanks undergo a low-temperature pre-sintering process, developing sufficient physical strength for handling.
5. High-Temperature Sintering: Finally, the carbide blanks are sintered at temperatures ranging from 2500ºF to 2900ºF. This high-temperature sintering causes a dramatic shrinkage, almost 40% volume reduction, resulting in an extremely dense and hard material.

Carbide cutting tools have revolutionized various industries with their exceptional hardness, heat resistance, and longevity. Understanding the intricate details of the cutting process and the meticulous production of carbide tools sheds light on their unmatched performance in the world of machining. Whether it's the intense forces at the cutting edge or the precise control of cobalt binder content and carbide grain size, carbide tools continue to shape the future of manufacturing and engineering.