As outlined in the article “Choosing Your Carbide Grade: A Guide” from Modern Machine Shop, understanding the intricacies of carbide grades is essential for optimizing machining performance. Carbide grades, in machining terms, go beyond the metallurgic definition of tungsten carbide (WC) sintered with cobalt. They encompass a variety of sintered tungsten carbide combinations with different coatings and treatments, making it challenging for end-users to compare grades across various suppliers, especially when the right grade significantly impacts cutting conditions and tool longevity.
At the core of any carbide grade lies the substrate, which typically consists of 80 to 95 percent tungsten carbide. This substrate’s properties are modified by adding alloying elements, with cobalt being the primary one. A higher cobalt content increases toughness, while a lower cobalt content enhances hardness. The hardest substrates, with a hardness of up to 1800 HV, offer superior wear resistance but are brittle and suitable only for stable conditions. Conversely, tougher substrates, with a hardness around 1300 HV, can withstand interrupted cuts and less favorable conditions but wear out more quickly at higher speeds.
The key to selecting the appropriate carbide grade lies in balancing hardness and toughness to match the specific application requirements. A grade that is too hard may cause micro-breakages or catastrophic failure, while an overly tough grade may result in rapid wear or necessitate slower cutting speeds, thus compromising productivity. Finding the right equilibrium is critical to achieving optimal machining results.
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Article with all rights reserved, courtesy of mmsonline.com