Cutting Die Unbalanced Thrust

Posted by stephens on Oct 16, 2009 in Engineering Decisions, Equations | 0 comments

Forces in a cutting die are equal and opposite. So what happens when cutting occurs on one side of a cutting component? Unbalanced thrust.

The issue with unbalanced thrust is should the cutting component be heeled or keyed to counteract the lateral force.

The first step to this decision is to quantify the magnitude of unbalanced thrust. The equation for unbalanced thrust in a cutting die is:

• Fut = dc • Fc / t

where:

• Fut = Force of unbalanced thrust (kN)
• dc = die clearance (mm)
• Fc = cutting force (kN)
• t = material thickness (mm)

For example, a die with 0.12 mm die clearance per side, 108 kN cutting force on 1.5 mm thick material has lateral force or unbalanced thrust of:

• Fut = dc • Fc / t
• Fut = 0.12 • (108 / 1.5)
• Fut =  0.12 • 72
• Fut = 8.64 kN

This means that 8.64 kN of lateral force is acting on the cutting component. Lateral force, or unbalanced thrust is perpendicular to the cutting vector and not necessarily horizontal.