Pressworking — shape control in a bending operation During a standard press brake bending operation on sheet metal, the workpiece tends to conform to which geometric feature of the tooling?

Introduction / Context:
Bending is one of the most common sheet-metal operations. The radius and angle achieved depend on the punch, die opening, material thickness, and springback. Understanding which tool primarily controls the bend geometry is essential for accurate press brake setups.

Given Data / Assumptions:

• Air bending or bottoming with standard V-dies is considered.
• Punch nose radius, die opening (V), and material thickness are within typical ranges.
• Springback is accounted for by overbending.

Concept / Approach:
During bending, the sheet wraps around the punch nose as the punch descends into the die opening. In bottoming/coining, the inside bend radius closely approximates the punch nose radius, while in air bending it is influenced by both punch radius and die V-opening but is still primarily governed by the punch. Thus, the metal largely takes the shape imposed by the punch (angle and nose radius), with springback slightly opening the angle after unloading.

Step-by-Step Solution:
Set punch and die: select punch nose radius near desired inside radius.Form: sheet wraps around the punch; fibers on the inside compress, outside extend.Release: springback occurs; compensate by overbending or using coining.Result: inside radius ~ punch radius; angle follows punch/die geometry.

Verification / Alternative check:
Shop charts for air bending specify inside radius as a function of die opening and punch radius, confirming punch dominance in shape control.

Why Other Options Are Wrong:

• “No” and die-only answers ignore the punch’s governing role.
• Stripper plates are used in blanking/piercing, not bending.
• Lubrication affects friction, not the fundamental geometry.

Common Pitfalls:
Expecting the die to fix the inside radius in air bending; it mostly limits the outside radius and angle while the punch nose sets the inner radius.

Final Answer:
Yes — it follows the punch shape (inside radius ~ punch nose radius)