The _____ in a broaching tooth is provided to prevent rubbing of the tool with the workpiece.

Explanation:

Back-off Angle in Broaching Tools

• The back-off angle in a broaching tool is a critical feature that ensures smooth operation and prevents the tool from rubbing against the workpiece. This angle is provided on the cutting teeth of the broaching tool to ensure that only the cutting edges make contact with the material being machined. By avoiding unnecessary contact between the tool and the workpiece, the back-off angle minimizes friction and heat generation, leading to improved tool life and better surface finish of the workpiece.

Function of the Back-off Angle:

• The back-off angle is essentially a relief angle that ensures the clearance between the tool and the workpiece. When the tool moves through the material, this angle ensures that only the cutting edge interacts with the workpiece, while the rest of the tool remains clear. This design prevents rubbing or dragging of the tool's body against the workpiece, which could otherwise lead to wear, damage, and poor machining results.
• The back-off angle is particularly important in broaching operations, as broaching tools typically have multiple cutting teeth arranged in a series. Each tooth removes a small amount of material, progressively shaping the workpiece to the desired dimensions. Without an appropriate back-off angle, the subsequent teeth might rub against the material, causing heat buildup, tool wear, and potential damage to the workpiece.

Advantages of the Back-off Angle:

• Prevents rubbing and excessive friction between the tool and the workpiece.
• Reduces heat generation during the machining process.
• Improves tool life by minimizing wear.
• Enhances the surface finish of the machined part.
• Ensures efficient and smooth material removal by each cutting tooth.