Cutting tools play a vital role in machining, making operations faster, more efficient, and precise. Yet, with so many types of cutting tool materials available—each designed for a specific purpose—choosing the right one can be confusing.
Selecting the appropriate cutting tool is critical for achieving optimal performance, reducing wear, and ensuring quality results. In this article, we’ll guide you through the classification of cutting tools and provide practical tips to help you choose the best tool for your machining tasks.
Let’s explore cutting tools in detail and uncover how to make the right selection for every operation!
What Is a Cutting Tool?
A cutting tool is a sharp, wedge-shaped device designed to remove material in order to shape or manufacture parts. These tools are typically made from hardened materials with specialized compositions to withstand the stresses of cutting. The cutting action occurs due to the relative motion between the tool and the workpiece. While cutting tools are most commonly used for metals, they can also be applied to a wide range of other materials.
Cutting tools are often mounted on various machines to perform operations such as drilling, turning, milling, and more. They come in diverse geometries, with different clearance angles, edge shapes, and cutting profiles, each optimized for specific types of machining tasks. This variety allows manufacturers to achieve precision, efficiency, and versatility in their cutting operations.
Which Type of Tool Is Designed for Cutting Only?
In manufacturing, different materials require specific cutting tools, each engineered with unique properties to ensure efficient material removal. Tools designed exclusively for cutting are selected based on the workpiece material, cutting conditions, and desired precision.
The main types of cutting tools based on their composition and properties include:
Carbon Steel Tools – Economical and suitable for low-speed cutting of softer metals.
High-Speed Steel (HSS) Tools – Durable and heat-resistant, ideal for medium-speed cutting of metals.
Cemented Carbide Tools – Extremely hard and wear-resistant, suitable for high-speed cutting and tough materials.
Ceramic Tools – Heat-resistant and ideal for high-speed cutting of hardened metals.
Cubic Boron Nitride (CBN) Tools – Superhard tools designed for cutting hardened steels and ferrous alloys.
Diamond Tools – The hardest cutting tools, perfect for machining non-ferrous metals, composites, and abrasive materials.
Each of these tools is optimized for cutting performance, wear resistance, and precision, ensuring that the right tool is selected for each specific application.
1. Carbon Steel Tools
Carbon steel cutting tools are best suited for low-speed machining operations. They are typically composed of 0.6–1.5% carbon, 0.5% manganese, and silicon, with the addition of chromium (Cr) and vanadium (V) to enhance hardness and refine grain structure.
However, carbon steel tools have limited heat resistance and are not ideal for high-speed or modern machining operations, as they can lose hardness at temperatures above 240°C.
These tools are commonly used in applications such as milling cutters, twist drills, and forming tools for cutting soft materials, including brass and magnesium. Their affordability and ease of fabrication make them suitable for simple, low-temperature cutting tasks.
2. High-Speed Steel (HSS) Tools
High-speed steel cutting tools are alloyed with elements such as chromium, molybdenum, tungsten, and vanadium, which enhance wear resistance, toughness, and heat tolerance. HSS tools can withstand temperatures up to approximately 650°C, beyond which they begin to lose hardness. Surface treatments, such as coatings or heat treatment, can further extend their lifespan.
HSS tools are commonly used in broaches, drills, milling cutters, and single-point cutting tools for lathes, making them versatile for a wide range of machining operations. Their combination of toughness and moderate heat resistance makes them suitable for medium-speed metal cutting tasks.
3. Cemented Carbide Tools
Cemented carbide tools are manufactured through powder metallurgy and consist of tungsten, titanium, or tantalum carbide particles bound with cobalt. When nickel or molybdenum is used as a binder, the tool is referred to as a cermet. These tools are exceptionally hard and can retain their hardness at temperatures approaching 1000°C, making them ideal for high-speed and heavy-duty cutting.
Cemented carbide tools with higher cobalt content are suitable for rough cutting, while those with lower cobalt are better for finishing operations. They are widely used for machining non-ferrous metals, cast iron, and non-metallic materials due to their superior hardness, wear resistance, and stability under high cutting temperatures.
4. Ceramic Tools
Ceramic cutting tools are typically made from aluminum oxide or silicon nitride, materials known for their chemical inertness and resistance to metal bonding. They offer exceptional hardness, wear resistance, heat resistance, and corrosion resistance. Ceramic tools can operate at speeds up to ten times faster than high-speed steel tools and remain stable at temperatures up to 1800°C, often eliminating the need for coolant.
These tools are ideal for high-speed, hard, and dry cutting applications, particularly when machining difficult-to-cut materials. Ceramic tools are best suited for CNC machines, where they can fully exploit their high-speed capabilities while maintaining precision and durability.
5. Cubic Boron Nitride (CBN) Tools
Cubic boron nitride is the second-hardest material used in cutting tools, prized for its extreme hardness, excellent thermal conductivity, and outstanding thermal stability. CBN tools can withstand very high temperatures without losing performance, making them ideal for demanding cutting operations.
CBN tools are especially effective for machining hardened steels, hard cast irons, cemented carbides, and superalloys. However, they are not suitable for materials with high plasticity, as these can cause built-up edge formation and reduce cutting efficiency. Their precision and durability make CBN tools a top choice for high-performance metal cutting.
6. Diamond Tools
Diamond is the hardest and most rigid natural material, renowned for its exceptional wear resistance, thermal conductivity, and ability to produce precise, high-quality finishes. Diamond cutting tools deliver excellent surface quality and dimensional accuracy, making them ideal for applications that demand precision.
Despite these advantages, diamond has limited thermal stability and begins to lose hardness at temperatures above 700–800°C. As a result, diamond tools are not suitable for cutting ferrous metals. However, they excel at cutting non-ferrous metals, composites, ceramics, and other non-metallic materials at extremely high speeds, offering unmatched performance in these applications.
How to Choose the Right Cutting Tools for Machining
Selecting the appropriate cutting tool is critical for achieving precision, efficiency, and durability in machining operations. Several factors must be considered to match the tool with your material, machine, and desired outcome. One of the most important considerations is the number of cutting edges.
1. Number of Cutting Edges
Cutting tools may have one or more edges that engage with the workpiece simultaneously. The number of cutting edges directly affects the speed, accuracy, and type of operation. Cutting tools are typically classified as follows:
· Single-Point Cutting Tools
As the name suggests, single-point cutting tools have only one primary cutting edge. They are mainly used for turning, shaping, and planning operations. Examples include single-blade reamers, which are essential for enlarging and finishing holes in workpieces.
· Double-Point Cutting Tools
Double-point cutting tools feature two cutting edges that operate simultaneously in a single pass. Drills are the most common example of this type, often with two or more cutting edges. These tools are ideal for drilling operations where material removal efficiency is important.
· Multi-Point Cutting Tools
Multi-point cutting tools have more than two cutting edges, ranging from three to several hundred. This allows for faster material removal and higher efficiency, making them highly suitable for modern manufacturing techniques. Examples include milling cutters, grinding wheels, broaches, and gear hobbing cutters.
Choosing the right type of cutting tool based on the number of cutting edges ensures optimal performance, better surface finish, and longer tool life in your machining operations.
2. Size of Tool
The size of your cutting tool is very important for achieving the desired cut on your workpiece. Each cutting machine or process has specific criteria. For instance, choosing a small lathe tool may not be as effective as a larger one, which is more rigid and performs better. On the other hand, excessively large milling tools may spend more time cutting air and are more expensive. Therefore, always select an appropriately sized cutting tool, keeping small cutting tools for metals as a first choice.
3. Determine the Application
Before selecting the right cutting tool, you should first determine its intended application. Generally, there are two main purposes: one is manufacturing, which includes sizing, shaping, and drilling holes; the other is removing, which involves finishing and smoothing the surface. Based on this, you should choose the cutting tool that best suits your specific application.
4. Material
One of the most important considerations is knowing both the material of your workpiece and that of your cutting tool. Not every cutting tool is suitable for every workpiece material.
For example, using a diamond cutting tool on ferrous metals such as steel or cast iron is not feasible. Similarly, carbon steel tools are unsuitable for high-temperature applications, and some tools are ineffective for slow-speed cutting operations.
Therefore, it is essential to carefully match the material of your cutting tool with that of your workpiece to achieve optimal results.
5. Power Requirements
Your cutting tool should also match the power capacity of your machine to ensure efficient and precise cutting. For instance, if you operate a 20-hp milling machine, select a tool that uses approximately 80% of the machine’s power. Always refer to the power/RPM chart in your machine’s manual to make the correct choice.
6. Chip Control
Excessive or irregular chip formation is a clear sign of poor cutting performance. While well-formed chips indicate normal operation, bad chips suggest that adjustments are needed. To address this, you may need to replace the cutting tool or modify parameters such as cutting radius, depth, speed, and feed rate. Proper chip control ensures smoother operations, better surface finish, and longer tool life.
Conclusion
With this knowledge, you are now better equipped to select the right cutting tools for your machining operations. Always choose tools based on the material and intended application of the workpiece to ensure precise, efficient, and high-quality cuts.
