The Angle on which the Strength of the Tool Depends

The angle on which the strength of the tool depends is the rake angle.

Introduction
In mechanical engineering, the rake angle is an important parameter that affects the performance and strength of cutting tools. It refers to the angle between the rake face of the tool and the direction of cutting motion. The rake angle plays a crucial role in determining the cutting forces, chip formation, and tool life.

Importance of the Rake Angle
The rake angle affects several aspects of cutting tool performance, including:

1. Chip Formation: The rake angle influences the type of chip formed during the cutting process. A positive rake angle (when the rake face is inclined towards the cutting direction) results in continuous chips, while a negative rake angle (when the rake face is inclined away from the cutting direction) produces segmented or discontinuous chips. The type of chip affects cutting forces, heat generation, and chip evacuation.

2. Cutting Forces: The rake angle has a significant impact on the magnitude and direction of cutting forces. A positive rake angle reduces cutting forces by decreasing the friction between the tool and workpiece. On the other hand, a negative rake angle increases cutting forces, which can lead to higher tool wear and power consumption.

3. Tool Life: The rake angle directly affects tool life. A positive rake angle improves tool life by reducing the cutting forces and heat generation. It also promotes better chip control and evacuation. Conversely, a negative rake angle decreases tool life due to increased cutting forces, heat, and tool wear.

Optimization of the Rake Angle
The selection of the rake angle depends on various factors, including the machining operation, workpiece material, cutting speed, and tool material. The goal is to optimize the rake angle to achieve the desired cutting performance, tool life, and surface finish.

1. For soft materials: A positive rake angle is generally preferred as it reduces cutting forces and improves chip control.

2. For hard materials: A negative rake angle may be used to enhance tool strength and withstand higher cutting forces. However, this can increase power consumption and heat generation.

3. For intermittent cutting: A neutral or zero rake angle is often chosen to balance cutting forces, chip control, and tool life.

Conclusion
In summary, the rake angle is a critical factor that influences the strength and performance of cutting tools. It affects chip formation, cutting forces, and tool life. The selection and optimization of the rake angle depend on various factors, including the material being machined and the specific machining operation.