The tool you use is the most important factor in achieving a perfect finish on the lathe. Turning tools are specialised tools attached to a lathe to produce turned parts, and their ability to withstand stresses and resist deformation is crucial for effective and durable performance.
These tools do the work, and their movement determines the final shape of the workpiece. There are many types of turning tools, each designed for specific purposes.
Therefore, it is important to understand the function of each tool in order to choose the right one for your project. Precision in lathe cutting tools is essential for achieving high-quality, detailed results and ensuring clean, accurate machining.
In this post, we’ll walk you through how to use the most common woodturning tools. We’ll discuss their construction, features and applications. Let’s get started.
What Are Cutting Lathe Tools?
Cutting or turning tools are used to drill holes or create knurl marks on a workpiece during machining. These tools come in different shapes, materials, and designs, and the difference between various lathe cutting tools lies in their specific properties and applications, which impact their suitability for particular machining tasks. Each tool is unique in its configuration.
There is a wide range of lathe cutting tools available to address different machining needs, offering versatility in terms of materials, shapes, and operational conditions.
A bevelling tool, for example, has a 45-degree angle specifically designed to cut the edge of a workpiece. While effective for this purpose, it is unsuitable for other tasks. If you want to familiarise yourself with these tools, you first need to get a clear picture of their functions and capabilities.
In addition to lathe cutting tools, other cutting tools such as drag knives and tangential knives are used for specialized applications requiring precision and versatility.
Introduction to Metal Cutting
Metal cutting is a cornerstone of modern manufacturing, enabling the transformation of raw materials into components with precise shapes, sizes, and surface finishes. At the heart of this process are cutting tools—rigid, wedge-shaped devices designed to remove excess material from a workpiece with accuracy and efficiency.
The cutting process relies on the interaction between the cutting tool and the workpiece, where a relative velocity is established, typically by rotating or moving the workpiece against the tool using machine tools such as lathes, milling machines, or drilling machines.
The primary goal of the metal cutting process is to achieve the desired shape and dimensions while maintaining high quality and minimizing waste. Cutting tools must be constructed from materials that offer high hardness and durability, allowing them to withstand the intense heat and friction generated during machining.
Whether employed in turning, milling, or drilling operations, these tools are engineered to deliver consistent performance, ensuring that each layer of material is removed cleanly and efficiently. By selecting the right cutting tool and optimizing the cutting parameters, manufacturers can achieve superior accuracy, surface quality, and productivity in every machining operation.
Classification of Lathe-Cutting Tools
It can be difficult to differentiate lathe-cutting tools because they come in many shapes and sizes. However, each tool can be categorised into one of the following groups. Standardized systems are used to classify and organize lathe-cutting tools for easier identification and selection. When you’re in the workshop, it’s much easier to recognise which turning tool is which if you know these groups.
Following established practice in tool classification helps ensure optimal performance and efficiency in the workshop.
Class 1. Lathe-Cutting Tools Based on Material
All kinds of metallic and non-metallic machine tools are used when making objects. Since these different workpieces have different mechanical and chemical properties, you need different tools to cut them properly.
For this reason, we make cutting tools from specific materials suitable for specific tasks. Selecting the right tool material is crucial for achieving optimal performance and durability in machining operations.
There is a wide range of tool materials available, each offering unique properties tailored for different applications, such as hardness, toughness, and resistance to high temperatures. The choice of tool material and tooling system directly impacts the workpiece surface quality, tool life, and efficiency.
Matching the tool to the cut material is essential for precise and efficient results, whether you are using lathe tools, drills, or other cutting implements. Modular tooling systems also provide adaptability for various lathe operations.
Let’s take a look at some of the most common tool materials.
High-speed steel (HSS)
High-speed steel tools were first produced in the late 1940s to improve high-carbon steel tools. HSS has a better chemical composition, which allows it to cut faster and more effectively.
For this reason, we often refer to it as a “high speed steel lathe tool set.” This improvement means that HSS is also tough and retains its shape even when very hot. The different alloys it is made of give it this property.
The main components of HSS are Fe (iron) and C (carbon), and the general formula for HSS is Fe-C-x. The “x” can be things like tungsten, vanadium or cobalt. These components make HSS tough and able to withstand high temperatures. HSS tips are commonly used in cutting tools, providing a durable and sharp cutting edge that enhances tool performance.
Carbide cutter
Most carbide end mills have a steel body and removable blades with carbide brazed onto their edges. These carbide edges ensure an excellent surface finish that does not wear quickly. Carbide-cutting tools can last up to 99 times longer than HSS tools, depending on how long they last.
This is because they can remain sharp even when running fast or hot. There are two main types of them: carbide-tipped tools and carbide inserts. Carbide-tipped tools are usually one-piece, so you may need to replace the whole cutter when it becomes blunt. The manufacturing process of carbide tips involves precise bonding techniques to ensure maximum durability and cutting efficiency.
You can simply rotate the insert with carbide inserts when one side is worn. This maintains the size and quality of the surface finish for longer. Carbide-tipped saw blades often feature specially designed teeth that provide efficient material removal and long-lasting performance.
Cubic boron nitride (CBN)
CBN, or cubic boron nitride, is one of the strongest materials on Earth after diamond. In manufacturing cutting tools for lathes, they can cut metals and alloys very quickly without having to cool down during cutting.
The reason for these high cutting speeds is that CBN is chemically inert, i.e., it does not react with carbon or its alloys. CBN is also more heat resistant than carbide and HSS combined and even more heat resistant than diamond cutters. CBN exhibits high hot hardness, allowing it to maintain its cutting edge and hardness at elevated temperatures, which is critical for machining hard materials. CBN tools are also highly resistant to chipping during high-speed machining, ensuring a longer tool life and consistent performance. This speed and efficiency can reduce the overall cost of manufacturing products by around 60%.
Diamond lathe tool
Diamond lathe tools are the best for cutting and finishing with great accuracy. They are usually made as single-point cutting tools, as diamonds are expensive and difficult to find. In most cases, the diamond tip is joined to the working part of the tool by welding or glueing. Diamond tools are precisely ground to achieve a sharp and accurate cutting edge, which is essential for high-precision applications. Grinding wheels are commonly used in the preparation and sharpening of diamond tools to maintain their superior cutting performance.
Ceramic lathe tool
Ceramic lathe tools are popular because they are chemically stable and can produce both rough and smooth surfaces. They do not wear out so quickly and can withstand much heat.
Ceramic tools can also cut harder materials at high speeds without the need for coolant, just like CBN. The ceramic insert turning tool is a common type. The insert is screwed into a tool holder. You can turn the sides as with carbide inserts to maintain the machining quality of the tool for longer. The hardness of ceramic tools is often assessed through measurement methods such as Knoop or Vickers tests, which are important for predicting tool performance and wear. Ceramic tools are also highly resistant to chipping and cracking, making them suitable for demanding machining conditions.
In addition to these, drills are another common application of advanced tool materials, especially for machining hardened steels and other challenging materials. Specialized tools such as grooving or knurling tools are designed to create a notch in the workpiece for specific machining operations. The selection of appropriate tool materials and tooling systems is essential for achieving the desired workpiece surface quality and ensuring compatibility with the cut material.
Class 2. Lathe-Cutting Tools Based on Operation
You can also recognise the type of turning tools by what they do. We group the tools according to their function, e.g., turning, threading, chamfering, moulding, facing, drilling, grooving, and knurling tools. The orientation of the cutting edge or tool is crucial for each operation, as it directly affects the precision and quality of the machining results.
Turning tools: One of the most widely used machining processes is turning. This is the process by which additional material is removed from a workpiece. It can be a rough turning process to create the basic shape or a precise turning process to make the surface look nice.
Thread cutting tools: A threading tool is used to produce shapes that look like threads, e.g. on screws or bolts. This is usually the last step after turning a cylindrical workpiece.
Chamfering tools: Chamfering tools smooth surfaces or remove rough edges on a workpiece. This process, also known as chamfering, creates a bevel at a 45-degree angle, making the finished product safer to handle.
Form tools: This is another typical tool used when making things. As the name suggests, you can use it to shape a workpiece into the form you want.
Facing tools: A facing tool is a turning tool used for finishing workpieces. It is positioned at right angles to the rotating workpiece, and the relief angles prevent other parts of the tool from getting in the way during machining.
Boring tools: Boring tools are single-edged tools used to drill a larger hole in a workpiece. They can be used to produce a conical or cylindrical shape.
Grooving tools: You can use grooving tools to form grooves or furrows in a cylindrical workpiece, either internally or externally. As this process must be precise and accurate, it is usually carried out using CNC machines rather than by hand.
Knurling tools: These are used to create criss-cross patterns on the surface of a workpiece. This knurling pattern makes it easier to hold the fabric in place as it increases friction.
Class 3. Lathe-Cutting Tools Based on Structure
The third method of distinguishing cutting tools is the way they are made. These tools can be made from a single solid piece or a mixture of different materials. They are categorised into three groups: one-piece, clamped and welded tools.
Single body tools: As the name suggests, a one-piece tool contains all parts in one piece. This means that all the important parts, including the cutting edges, shank and other parts, are in a single file.
Tools with clamps: You can usually replace these tools. They consist of tool inserts that are screwed or clamped onto a shank to form a complete component. These inserts usually have more than one cutting edge.
Welded tools: These tools contain different parts or cutting edges that are welded or brazed together. This can improve the turning or finishing of the tool. Many drilling and grooving tools belong to this group.
Class 4. Lathe Cutting Tools Based on Feed Direction
Lathe cutting tools can also be classified according to the direction in which they move along the workpiece during machining. This classification is essential because the feed direction determines the type of operation that can be performed and the final shape achieved. The 6 main types of lathe cutting tools based on feed direction are:
Longitudinal Cutting Tools:These tools move parallel to the axis of the workpiece, removing material along its length. Longitudinal cutting is commonly used for turning operations, where the goal is to reduce the diameter or create a uniform cylindrical shape. This approach is ideal for producing shafts, rods, and other elongated components.
Cross-Cutting Tools:Cross-cutting tools move perpendicular to the length of the workpiece, cutting across its diameter. This type of movement is typically used for operations such as parting off or creating grooves and notches. Cross-cutting is essential for separating finished parts from the stock material or for adding specific features to the workpiece.
Face-Cutting Tools:Face-cutting tools operate along the end face of the workpiece, removing material from its surface. This method is used in facing operations to produce flat, smooth ends or to achieve precise length measurements. Face-cutting is crucial for preparing workpieces for further machining or assembly.
Right-hand turning tools: These tools move from right to left in the direction of the chuck when they are used.
Left-hand turning tools: These tools remove the crisps when they move from left to right, as the name suggests.
Round nose lathe tools: These tools are also known as centre turning tools. The main cutting edges can have a 45-degree angle on the left and right sides, which is the same.
Each of these cutting tools is designed to optimize material removal for its specific feed direction, ensuring efficient machining and high-quality results. By understanding the feed direction, machinists can select the appropriate tool to achieve the desired shape and surface finish on any workpiece.
The Importance of Cutting Edge
The cutting edge is the defining feature of any cutting tool, playing a pivotal role in the success of the metal cutting process. As the part of the tool that directly engages with the workpiece, the cutting edge is responsible for shearing away material and shaping the final product. A well-crafted cutting edge is essential for achieving precise, high-quality machining operations, as it determines the efficiency, accuracy, and surface finish of the workpiece.
To withstand the demands of metal cutting, the cutting edge must be exceptionally sharp and made from materials with high hardness, such as high-speed steel or carbide. This ensures the cutting tool can maintain its shape and resist wear, even under the intense heat and pressure generated during machining. The geometry of the cutting edge—including its angle, shape, and size—directly influences the tool’s performance, affecting factors like cutting force, chip formation, and the smoothness of the finished surface.
A high-quality cutting edge not only improves the overall efficiency of the cutting process but also extends the life of the tool, reducing downtime and the need for frequent replacements. By selecting cutting tools with optimal cutting edge design and material, machinists can achieve superior results in every metal cutting operation, ensuring that each workpiece meets the highest standards of accuracy and quality.
Components of a Lathe-Cutting Tool
Now that we’ve covered the classifications let’s look at the different parts of lathe cutting tools that allow them to produce such high-quality work.
Shank: The shank is the tool’s body or the part that connects to the holder. It’s the area of the tool without any special styling, and it’s usually held in place by friction.
Cutting Edge: Also known as the tool lips, the cutting edge is the part of the tool that does the work. It’s usually brazed with a hard coating like diamond or carbide. This is the point that shapes the workpiece or removes chips.
Face: The face is the part where chips fall during machining. It’s curved to allow chips to flow away and prevent clogging.
Lathe-Cutting Tool Angles: Tool angles are intentionally created to streamline the machining operation. The three major angles are rake, relief, and cutting-edge angles. Rake angles control the chips, while relief angles prevent the tool from rubbing against the workpiece, which gives a cleaner cut and prevents the tool from wearing out.
Nose or Cut-Off Point: This is the rounded part of the tool where the main and auxiliary cutting edges meet. The rounded nose radius helps to give a cleaner surface finish and makes the tool last longer.
Flank: Every single-point tool has two cutting edges and two flanks. The major flank is next to the side cutting edge, and the minor flank is next to the end cutting edge.
Heel: The heel is the rounded part that joins the flanks and the tool’s base.
Factors to Consider Before Choosing Lathe-Cutting Tools
Creating quality fabrication starts with choosing the right lathe-cutting tools. Here are some things you should think about to ensure optimal performance and efficiency.
- 1. Lathe Tools Coating: Coating your tools is a sure way to prevent them from wearing out or rusting. The coating also gives the tools mechanical advantages against forces like heat and friction that could deform them. This could mean applying inert compounds like CBN or carbide.
- 2. Cutting Speed and Feed Rate: You can’t cut all materials at the same speed. Harder or thicker materials need more torque, which translates to a lower speed, while softer materials can be cut faster. It’s important to consider the material you’re working with to determine the right speed and tool for the job.
- 3. The Workpiece and Type of Material Used for the Tool: Before purchasing a tool, note the workpiece material. As a rule, your cutting tool must be tougher than the workpiece. This hardness can be measured with a Brinell hardness tester.
- 4. The Type of Finish You Need: You must also consider the finish you want to achieve. Whether it’s turning, cutting, or knurling, a corresponding tool will do the job perfectly. Make sure you know what you want the final product to look like before you decide on a tool.
- 5. The Type of the Lathe Machine: Finally, think about the lathe machine you’re using. The main types are manual and automated CNC lathes. While the tools used might be similar, their shapes and sizes could differ depending on the machine’s architecture.
Conclusion
The secret to producing top-quality finishes in any metal cutting process is picking the right cutting tool. Hopefully, this guide has given you all the information you need to identify the lathe-cutting tools that will meet your machining needs, no matter what machine you use.