Introduction

In the world of machining and manufacturing, precision is paramount.Whether you are crafting intricate components for an aerospace engine or shaping everyday objects, understanding the geometry of a single point cutting tool is essential for achieving accuracy and efficiency. In this blog, we will explore the critical aspects of single point cutting tool geometry and how it influences the machining process.

The Basics of Geometry Single Point Cutting Tools

To begin with, a single point cutting tool is essential in machining operations, such as turning, milling, and drilling. Generally, it’s called "single point" because it has one cutting edge. In fact, this edge removes material efficiently. Moreover, tool geometry is crucial. Specifically, it shapes and finishes the workpiece. Consequently, good design boosts performance. Furthermore, it lowers tool wear. Therefore, proper geometry matters. Meanwhile, machinists check tool condition. Additionally, angles affect chip flow. Notably, rake and clearance are key. On the other hand, poor geometry causes defects. Nevertheless, modern tools help accuracy. Besides, coatings increase tool life. In contrast, bare tools wear quicker. Thus, tool knowledge is vital. Indeed, it's critical in manufacturing. As a result, industries depend on it. Likewise, automation aids use. Eventually, tool performance affects quality. In conclusion, single point tools stay relevant.

The different view of single point cutting tool is shown in Figure 1.According to ASA (American Standard Association) there are seven parameters of tool geometry as mentioned below as

`alpha_b`,`alpha_s`,`beta_e`,`beta_s`,`theta_e`,`theta_s`,R

Diagram of a cutting tool, labeled parts include shank, face, and angles: side rake, back rake, side relief, end relief, nose radius, and cutting edges.

Figure 1

where `alpha_b` is the back rake angle; `alpha_s` side rake angle; `beta_e`,end clearance angle;`beta_s`,side clearance angle;`theta_e`,end cutting edge angle;`theta_s` and side cutting edge angle;R,nose radius.

Key Elements of Geometry Single Point Cutting Tool Geometry

1.Cutting Edge and Nose Radius

The frontier is the part of the tool which dissects the workpiece and pulls out the material. It is commonly constructed from a durable member such carbide or high-speed steel to withstand the forces and wear associated with the machining process.
In the case of turning and boring operations, the radius of the nose is known as the rounded end of the cutting tool. It has an effect on the surface finish and also in a way protects against chipping and vibration.

2.Rake Angle

Angle of the rake is the included angle between the cutting edge and a reference plane parallel to the machined workpiece surface. It decides on how well it cuts material. A positive rake angle (r > 0°) have decreasing cutting forces and create less heat whereas a lower rake angle (with r < 0) improve the strength of the tool even though the heat produced in the process is comparatively high.

3.Relief Angle (Clearance Angle)

The relief angle (also known as a Clearance Angle) is the angle between the cutting edge and the normal plane to the work surface. It creates clearance at the cutting edge thereby ensuring that it does not interfere with the workpiece that reduces friction and its subsequent heat generation.

4.Back Rake and Side Rake angle

The back rake refers to the angle between the tool's top surface and a plane parallel to the machined surface, impacting chip flow and cutting forces.
Side rake is the angle between the side flank and a line parallel to the machined surface, influencing the shearing action in machining.

5.End Relief and Side Relief angle

End relief is the relief positioned behind the cutting edge in the tool's rotation direction, preventing rubbing and enhancing tool longevity.
Side relief is the relief found on the tool's sides, aiding in chip removal and reducing friction.

Now we will see about all the above key elements in details.

Back Rake Angle and Side Rake Angle:

Back rake angle is the angle between the face of the tool and a line parallel with base of the tool measured in a perpendicular plane through the side cutting edge. If the slope face is downward toward the nose, it is negative back rake angle and if it is upward toward nose, it is positive back rake angle. This angle helps in removing the chips away from the work piece. Generally, ceramic or brittle tool materials have negative back rake angle. It ranges from -`5^circ`to `15^circ`.

Diagram illustrating cutting tool geometry with labeled parts: end cutting edge, side cutting edge, nose radius, and angles θe and θs.

Figure 2

Side rake angle is the angle between the base of the tool shank and the face of the tool measured in a plane perpendicular to the plane through the side cutting edge and right angle to the base. If the tool face is sloping upward towards the side cutting edge, side rake angle is positive and it is negative when it is sloping downward towards the side cutting edge. Positive side rake angle results in lower cutting force and low power consumption,and thus better cutting action. Negative side rake angle is used for rough cut and heavy duty applications. It ranges from -`5^circ`to `15^circ`.

End Relief Angle and Side Relief Angle:

The angle between the planes of the end flank immediately below the end cutting edge and line perpendicular to the base and right angle to the axis is known as end relief angle and the angle between the planes of the side flank immediately below the side cutting edge and line perpendicular to base along the axis is known as side relief angle. Relief angles are provided to ensure that no rubbing occurs between the work surface and flank surfaces of the tool. For general turning operations, they range from `5^circ`to `15^circ`.

Diagram of a cutting tool showing angles. It labels the "Back rake angle" and "End clearance angle" with Greek letters α and β for visual guidance.

Figure 3

End Cutting Edge Angle and Side Cutting Edge Angle:

End Cutting Edge Angle: The end cutting edge angle is the angle between the end cutting edge and a plane perpendicular to the tool’s axis. It provides clearance to prevent rubbing and drag. A smaller angle reduces contact with the workpiece, while a larger one may cause vibration or chatter. This angle is usually kept around 5°.

Side Cutting Edge Angle: The side cutting edge angle is the angle between the side cutting edge and a plane perpendicular to the tool’s axis. It reduces shock at the tool tip during cutting. This angle can range from 0° to 90°; increasing it thins the chip but widens it.

A diagram illustrating an angled tool with side rake and clearance angles labeled. Dashed lines show angles αs and βs, demonstrating tool geometry.

Figure 4

Nose Radius

The nose radius directly affects surface finish. A sharp tool point leaves a groove along the cutting path. Increasing the nose radius usually reduces tool wear and improves surface finish. Machinists typically select the largest nose radius for roughing operations. A larger radius allows higher feed rates, but they must also monitor for potential vibration issues.

Advantages of providing nose radius in cutting tool

Improved Tool Life: A small tip radius of the cutting edge better dissipates the cutting force between the different points of the cutting edge, reducing the stress concentration. This enhances tool life as, in this way, chipping or fracture are almost ruled out.
Surface Finish: the existence of a nose radius adds to the quality of the finish workpiece surface The curved edge reduces the possibility of leaving the flawing marks on the machined surface, mainly if you deal with materials that have poor machinability or tend to tear.
Reduced Cutting Forces: Using a nose radius allows the tool to engage the workpiece more smoothly, which significantly reduces cutting forces. Lower cutting forces minimize tool and machine wear and improve the dimensional accuracy of the machined part.
Improved Chip Control: The nose radius could affect chip formation by creating smaller, more controllable chips, which would imply the shorter edge radius. This can avoid the probability of chips bleeding, lower the chances of chip jamming, and thus increase machining efficiency.
Minimized Heat Generation: The curved surface of the nose radius helps reduce friction and heat during cutting. This is especially beneficial when machining heat-sensitive materials or at high cutting speeds, as it helps prevent thermal damage to both the tool and the workpiece.
Enhanced Stability and Rigidity: A small nose radius allows the tool to have the stability and the rigidity for cutting. This is critical in machining under harsh conditions because it maintains tool integrity, and precision of the entire machining operation.
Versatility in Machining Operations: Nose radius tool with cross-functions can be more versatile across several machining operations. Whatever it is turning, milling or drilling of the tool the addition of the nose radius promotes the versatility of the tool in a wider variety of applications.

Disadvantages of providing nose radius in cutting tool

Reduced Sharpness: A more rounded nose radius will provide less sharp tip. In situations where precision and fine detail matters, larger nose radiuses might not be the best solution as they could decrease the sharpness of the tool.
Limited Access in Tight Spaces: In cases where the workpiece has close geometric constraints or features, a large nose radius may hinder the tool from reaching these regions. This is a limitation in machine tools that have complex machining operations where there is a need for exact tool movement.
Increased Cutting Forces in Some Cases: While a smaller nose radius generally reduces cutting forces, an overly large radius can increase them—especially with softer materials. This may lead to greater tool wear and reduced machine stability.
Tool Chatter and Vibration:Larger Nose radius can lead to tool chatter as well as vibration problems, especially when machining at high speeds and with less stiff setups. Chat can affect surface finish, tool life, as well as overall machining efficiency negatively.
Compromised Corner Accuracy: Concerning the machining of corners or sharp edges, having too big a nose radius may cause the deviation from the intended geometry. This is a challenge in applications where the most important thing is the highest possible corner accuracy.
Increased Cutting Temperatures: A small nose radius reduces heat generation, while a larger nose radius increases cutting temperatures—especially during heavy milling. Excessive heat can thermally damage both the tool and the workpiece.
Tool Wear in Certain Materials: In some materials, like, hard alloys or ceramics, a big nose radius can speed up wear of the tool. The wear caused by a larger radius becomes more significant because more area of the tool and the workpiece gets in contact.

Applications and Implications of Geometry single point cutting tool

Understanding the geometry of a single point cutting tool is crucial for various machining processes:

Turning: In turning operations using lathe machines, machinists control the final shape and surface finish by selecting the appropriate cutting tool geometry. They use rake angle and nose radius to define the level of precision.
Milling: Engineers shape the cutting edges of milling cutters with specific geometries to mill slots, contours, and surface sections on a workpiece. The tool geometry directly influences material removal efficiency and surface quality.
Drilling: The tip geometry and flute design directly affect the hole size, accuracy, and chip ejection during drilling. Machinists must ensure proper relief and clearance angles to maintain high productivity.
Surface Finish: The characteristics of the cutting tool geometries determine the quality of surface finish of the workpiece. Accurate angles and radii in the design can minimize roughness and increase aesthetics of the design.

Conclusion

Single-point cutting tool geometry is crucial in precision machining, impacting cutting efficiency, surface finish, tool life, and accuracy. Engineers choose angles like rake, clearance, and nose radius based on the material and desired outcome. Optimizing geometry ensures smoother operations, less wear, and better quality, making it key to consistent, high-precision machining.

What is a Geometry of Single Point Cutting Tool in machining process?