The following are some commonly used materials for lathe tools :
1. High carbon steel:
High-carbon steel cutting tools are made of carbon steel with a carbon content between 0.8% and 1.5%. After quenching and hardening, they are easily softened by tempering during cutting and have been replaced by other tools such as high-speed steel. They are generally only suitable for cutting soft metals. Commonly used types include SK1, SK2, SK7, etc.
2. High-speed steel:
High-speed steel is a steel-based alloy commonly known as white lathe tool. It is made by adding alloying elements such as W, Cr, V, and Co to carbon steel with a carbon content of 0.7-0.85%. For example, 18-4-4 high-speed steel contains 18% tungsten, 4% chromium, and 4% vanadium. The frictional heat generated by high-speed steel lathe tools during cutting can reach up to 6000°C, making them suitable for speeds below 1000 rpm and thread cutting. Commonly used high-speed steel lathe tools include SKH2, SKH4A, SKH5, SKH6, and SKH9.
3. Non-cast iron alloy cutting tools:
This is an alloy of cobalt, chromium, and tungsten. Because it is difficult to machine, it is manufactured by casting, hence it is also called super-hard cast alloy. The most representative is stellite, which has excellent toughness and wear resistance. Its hardness is not affected at a temperature of 8200°C. Its heat resistance is far greater than that of high-speed steel, making it suitable for high-speed and deep cutting work.
4. Sintered and carbonized cutting tools:
Carbide cutting tools are products of powder metallurgy. Tungsten carbide tools are primarily composed of 50%–90% tungsten, with the addition of titanium, molybdenum, tantalum, and cobalt powder as a binder, and are then sintered by heating. Carbide cutting tools have a hardness higher than any other material, up to three times that of the hardest high-carbon steel. They are suitable for cutting harder metals or stone. Due to their brittle and hard nature, they can only be made into sheet form and then welded to a more resilient tool holder. This allows for easy replacement of the cutting edge or a new insert when the cutting edge becomes dull or chipped; such cutting tools are called disposable cutting tools. According to international standards (ISO), carbide cutting tools are divided into three categories—P, M, and K—based on their cutting properties, and are identified by blue, yellow, and red colors respectively. Category P is suitable for cutting steel and includes six types: P01, P10, P20, P30, P40, and P50. P01 is a high-speed finishing tool with a smaller number and higher wear resistance; P50 is a low-speed roughing tool with a larger number and higher toughness, and its tool holder is painted blue for identification. K-type tools are suitable for cutting brittle and hard materials such as stone and cast iron. There are five types: K01, K10, K20, K30, and K40. K01 is a high-speed finishing tool, and K40 is a low-speed roughing tool. These tool holders are painted red for identification. M-type tools fall between P-type and M-type tools and are suitable for cutting materials with higher toughness, such as stainless steel. These tool holders are painted yellow for identification.
5. Ceramic lathe tools:
Ceramic turning tools are made of alumina powder with the addition of a small amount of elements, and then sintered at high temperature. They have higher hardness, heat resistance and cutting speed than tungsten carbide, but because they are brittle, they are not suitable for discontinuous or heavy turning, and are only suitable for high-speed finishing.
6 diamond tools
For high-end surface finishing, round or edged industrial diamonds can be used for polishing. This results in a smoother surface and is mainly used for precision turning of copper alloys or light alloys. High speeds must be used during turning, with a minimum of 60-100 m/min and usually 200-300 m/min.
7. Cubic boron oxide (CBN)
It is a material that has been promoted in recent years. Its hardness and wear resistance are second only to diamond. This tool is suitable for machining hard and wear-resistant iron group alloys, nickel-based alloys, and cobalt-based alloys.
