Understanding Cutting Tool Angles

Cutting tools used in machining operations have specific angles ground onto them. These angles are crucial for efficient cutting, chip formation, tool life, and surface finish of the workpiece. The question asks to identify a specific angle formed between the face of the tool and a plane parallel to its base.

Defining Key Cutting Tool Angles

Let's look at the definitions of the angles provided in the options to determine which one fits the description:

• Rake Angle: This angle is defined as the angle between the face of the cutting tool and a plane parallel to the base of the tool, measured in a plane perpendicular to the base and the cutting edge. A positive rake angle helps in smooth chip flow and reduces cutting forces. A negative rake angle is used for cutting hard materials as it strengthens the cutting edge.
• Clearance Angle: Also known as relief angle, this is the angle between the flank of the tool and the surface of the workpiece being generated. It prevents the flank from rubbing against the workpiece, reducing friction and heat.
• Lip Angle: This is the angle between the face (rake surface) and the flank (clearance surface) of the tool. It is also known as the wedge angle or tool angle. It determines the strength of the cutting edge.
• Cutting Angle: This term can sometimes refer to the wedge angle (Lip angle) or be used in specific contexts like shear angle in chip formation. However, the description given in the question specifically points to the angle between the tool face and the base-parallel plane.

Analyzing the Question's Description

The question states the angle is "between the face of the tool and plane parallel to the base of the cutting tool". Based on our definitions above:

• The Rake angle is explicitly defined as the angle between the tool face and a plane parallel to the base.
• The Clearance angle is between the tool flank and the workpiece surface.
• The Lip angle is between the tool face and the tool flank.
• The term Cutting angle is general and doesn't specifically match the description provided.

Therefore, the angle that matches the description given in the question is the Rake angle.

Summary of Cutting Tool Angles

Understanding these different angles is fundamental in selecting and grinding cutting tools for various machining operations and materials.

Revision Table: Cutting Tool Angles

Additional Information: Types of Rake Angles

The rake angle can be further classified depending on how it is measured:

• Back Rake Angle: This angle is measured in a plane perpendicular to the base and parallel to the feed direction. It affects chip flow over the top of the tool.
• Side Rake Angle: This angle is measured in a plane perpendicular to the base and parallel to the cutting direction. It affects the direction of chip flow sideways.
• Effective Rake Angle: This is the rake angle encountered by the chip as it flows over the tool face, influenced by the tool orientation and cutting velocity.

The rake angle specified in the question typically refers to the orthogonal rake angle or the general concept applicable to different rake systems (like American Standard or Orthogonal Rake System).