Hard Metal Poses a Challenge for Cutting
Hard metal, also known as hard alloy, is a unique material that presents challenges when it comes to cutting and machining. With its exceptional hardness and durability, hard metal is widely used in various industries, especially in the manufacturing of cutting tools, machinery parts, and wear-resistant components. However, its very characteristics that make it so valuable also make it difficult to work with. In this article, we will explore the reasons why hard metal poses a challenge for cutting and the techniques that can be employed to overcome these challenges.
What is Hard Metal?
Before diving into the challenges associated with cutting hard metal, let’s first understand what this material is. Hard metal, or cemented carbide, is a composite material comprised of metal powders, typically tungsten carbide, and a binder metal, usually cobalt. The mixture is compacted and then sintered at high temperatures to form a solid, dense, and incredibly hard material.
The Challenge of Hardness
One of the primary characteristics of hard metal is its extreme hardness. With a hardness value of up to 90 HRA on the Rockwell scale, hard metal is significantly harder than most other materials commonly encountered in machining processes. This hardness poses a challenge when it comes to cutting since conventional cutting tools, such as high-speed steel, struggle to penetrate and remove material efficiently.
Cutting Tools for Hard Metal
To overcome the challenges presented by the hardness of hard metal, specialized cutting tools need to be used. The most commonly employed cutting tool material for hard metal is solid carbide. Solid carbide tools are made entirely of tungsten carbide, ensuring high wear resistance and toughness. Additionally, special carbide grades, such as micro-grain and ultra-fine grain carbides, are developed specifically for cutting hard metals.
Cutting Techniques for Hard Metal
In addition to using appropriate cutting tools, certain techniques can be employed to enhance the machining of hard metal. Some of these techniques include:
High-speed cutting (HSC): This technique involves using high cutting speeds and feeds along with optimized tool geometries and coatings to minimize tool wear and maximize material removal rate. HSC is particularly effective when used in combination with solid carbide tools.
Dry machining: Cutting hard metal generates a significant amount of heat, leading to thermal expansion and tool wear. Dry machining, or the use of minimal cutting fluid, can help dissipate the heat effectively, leading to improved tool life and surface finish.
Coolant application: In certain cases, when dry machining is not possible, coolants, such as water-soluble oils or emulsions, can be employed to reduce heat buildup and lubricate the cutting process. The selection of a suitable coolant depends on the specific application and tooling requirements.
Frequently Asked Questions
Q: Can hard metal be cut with traditional cutting tools?
A: No, the extreme hardness of hard metal requires specialized cutting tools, such as solid carbide, to achieve efficient material removal.
Q: Does cutting hard metal affect tool life?
A: Yes, cutting hard metal can significantly reduce tool life due to the high stresses and wear involved. However, employing techniques like high-speed cutting and proper coolant application can help improve tool life.
Q: What industries commonly use hard metal?
A: Hard metal finds applications in a variety of industries, including aerospace, automotive, oil and gas, mining, and general machining.
Q: Can hard metal be machined into complex shapes?
A: Yes, hard metal can be machined into complex shapes using advanced CNC machining techniques and specialized tooling.
Hard metal, with its exceptional hardness and durability, presents unique challenges when it comes to cutting. However, by employing specialized cutting tools, such as solid carbide, and utilizing techniques like high-speed cutting and appropriate coolant application, these challenges can be overcome. It is essential to select the right tools, techniques, and machining parameters to ensure efficient and cost-effective machining of hard metal. With the proper approach, hard metal can be transformed into highly precise and intricate components that play a vital role in various industries.