When choosing a cutting tool, you need to consider its material properties and how it will cut a particular material. Here we will go over the K factor, chemical stability, side cutting edge angle, and other considerations.
The right cutting tool just like a pencil grinder & straight grinder | Air Turbine Tools can save you time and money while ensuring quality results. Listed below are some essential factors you should consider when choosing a cutting tool. Ask your machine shop about specialized equipment if you are unsure what you need.
1. Material properties
The material properties of cutting tools are the basic requirements for the performance of different machining processes. Unlike knives, these tools must withstand high temperatures without losing their cutting edge, resist abrasion and adhesion, and have thermal conductivity.
These factors are crucial for the optimum performance of cutting tools. Here, we will discuss the material properties of cutting tools to understand their use and longevity.
Cutting tool life and speed are critical for the production process. Cutting tool life depends on several factors, including feed rate, tool geometry, and tool wear. These factors will impact tool life and increase productivity.
A good cutting tool will last for many hundreds of thousands of operations. Its life is determined by its ability to cut different materials at different speeds. In addition to cutting speeds, cutting tools must also have high wear resistance. For this reason, paying attention to cutting speed and feed rate before purchasing a new tool is essential.
2. K factor
The K factor of cutting tools describes the form of the cutting edge. The radius of the cutting edge is a function of many factors, including the material, the machining process, and the type of layer used.
However, it is usually evaluated based on cutting speeds of about 35 m/s. The monitoring area on the cutting edge is shown in Fig. 1. In addition, the size of the Sa and Sy affect the force load and heat load.
To measure the K factor of cutting tools, a tool is made of metal, alumina, and abrasive. Its K factor is influenced by the contact length a and the inclination g. As the rake angle g increases, the objective roughness function also increases.
The more complex the material is the higher the objective roughness function. A higher K factor means the cutting tool is not functioning optimally.
3. Chemical stability
Cutting tools made from cubic boron nitride (CBN) are among the most complex materials. They are also high-temperature resistant and exhibit excellent thermal stability. They are usually classified as low or high-c-BN. Low-c-BN tools contain no CBN at all, while high-c-BN tools contain 75-95 vol% boron nitride and metallic binders.
While greasy oils are the most commonly used cutting fluids, their other features are modest. In addition, they are expensive and cause significant smoke, which is not conducive to modern production. However, greasy oils can be formulated to be low-viscosity by mixing mineral oils with EP additives. This combination will result in good lubricity and extended tool life.
4. Side cutting edge angle
The back rake angle determines a cutting tool’s side cutting edge angle. It is the angle between the tool’s face and a perpendicular plane, measured from its base. If the slope is downward, the tip is positive, while if it is upward, the angle is negative.
Generally, the back rake angle is 5 to 15 degrees. This angle is vital to understand when designing and fabricating a tool.
A cutting tool’s rake angle is formed by the tool’s face and a line parallel to the tool’s base. This angle reduces friction between the device and workpiece, which results in thinner, more excellent chips.
However, positive rake angles lessen the cutting edge section’s strength and decrease the tool’s heat conduction capacity. Therefore, positive rake angles are better for hard metals and tough alloys, while negative rake angles are better for soft or brittle metals.
5. High yield strength at operating temperature
One of the best-known characteristics of HSS cutting tools is high yield strength at operating temperatures. However, in this type of cutting tool, the tool edge is loaded close to the limit of its yield strength, leading to severe adhesive wear.
This wear is further enhanced by cutting chemically aggressive materials. In addition to severe adhesive wear, HSS cutting tools are also prone to blunting their edges due to excessive friction. This article examines the factors that influence the yield strength of cutting tools.
A tool’s operating temperature is a primary factor determining the amount of heat generated by the device during cutting. The maximum temperature of a cutting tool increases with increasing cutting speed, as the temperature of the work material is affected by the amount of heat flowing into the tool.
This effect is particularly prominent in intermittent cutting. For these reasons, the operating temperature is crucial to a tool’s life and quality. To further improve tool life and minimize heat generation, the tool is required to be able to cut at a specific temperature.
6. Tool material
The high-temperature hardness of tool material determines its ability to withstand heat, prevent plastic deformation, and maintain toughness at high temperatures. This property also determines its wear resistance.
The more thermally stable a tool material is, the greater its ability to withstand a cutting process. The better its thermal conductivity, the lower its temperature during cutting. Choosing a material that can withstand high-speed cutting cycles is also important.
The quality of cutting tool material is essential in industrial applications. It dictates the amount of material removed, the surface finish, the tolerance, and the cost to the manufacturer.
A manufacturer can decrease scrap, improve production rates, and enhance part quality by selecting suitable tool material. This will ensure the long-term success of its operations. To choose the right tool material, a manufacturer must first consider the exact requirements of its cutting applications.