Selection of turning tool materials

The service life and production efficiency of turning tool depend on the cutting performance of turning tool material. Turning tool is composed of tool head and tool bar. The tool bar is generally made of carbon structural steel. As the tool head serves as cutting work, the tool head material must have the following basic properties:

Cold hardness: turning tool has high hardness at room temperature, that is, wear resistance of turning tool.

Red hardness: turning tool under high temperature conditions to maintain the hardness required for cutting, the highest temperature is called "red hardness"

Toughness: Strength and hardness of the cutting part of the lathe tool to withstand vibration and impact loads

The above three kinds of performance of turning tool materials are interrelated and mutually restricted, in the specific selection, according to the performance of the workpiece material and cutting requirements analysis and selection, but also combined with turning tool material in price, process performance to consider, so as to facilitate the relatively low cost of processing, grinding and welding manufacturing turning tool

At present, the main materials used for turning tool cutting part are high speed steel, hard alloy and non-metallic materials, carbon tool steel, alloy tool steel is used for drill, tap and other tools, less used as turning tool. This paper introduces two main materials of turning tool head: high speed steel and hard alloy.

1. High speed steel

High speed steel is a kind of alloy steel containing tungsten, chromium and vanadium, also known as front steel, wind steel and white steel. Commonly used are WL8Cr4v and W9Cr4v2 two grades, which use the most is WL8Cr4v high-speed steel

HSS materials are divided into two kinds of HSS with black skin and surface polished HSS. The former is untreated high speed steel, the latter is treated high speed steel. High speed steel has high hardness, certain red-hot hardness, good toughness and machining performance. HSS turning tool is easy to make, easy to sharpen, easy to sharpen. Because high speed steel has good toughness, it is often used for processing some parts with large impact and irregular shape. It is also often used for making fine turning tools, but because the red hardness is not as good as hard alloy, it is not suitable for high speed cutting.

2. Cemented carbide

Cemented carbide is formed from powder of refractory materials tungsten carbide, iron carbide and cobalt under high pressure. The red hardness of cemented carbide is very good, in 1000°C or so can still maintain good cutting performance, with high use strength, its bending strength can be as high as 1000-1700mpa, but brittle, poor toughness, shock, these shortcomings can be overcome by grinding reasonable Angle, therefore, cemented carbide has been widely used.