Sheet Metal & CNC Forming

Flow Forming & Shear Spinning Tooling Calculator

Compute theoretical spun cone wall thickness according to the Sine Law (t_f = t_0 * sin(α)), reduction ratio per pass, roller nose radius scallop finish, and axial forming thrust force.

1. Input Parameters

Initial Blank Thickness t0 (mm):

Original flat sheet or preform tube wall thickness.

Half Cone Angle α (degrees):

Included angle between cone wall and centerline mandrel axis.

CNC Roller Nose Radius r_R (mm):

Forming roller contact radius profiling the workpiece.

Axial Feed Rate f_z (mm/rev):

Linear axial travel per spindle revolution.

Material Flow Stress k_f (MPa):

Work-hardened dynamic yield strength (e.g. 6061-O: 180, 304SS: 550, Inconel: 850).

2. Calculation Results

Spun Wall Thickness (t_f)

2.00 mm

Thickness Reduction (R)

50.0%

Scallop Roughness (h_s)

1.9 µm

Estimated Axial Force (F_z)

14.2 kN

3. Geometric Visualizer

Tooling & Vector Prepress Engineering Notes

Sine Law Principle: In pure shear spinning, the final wall thickness is strictly governed by t_f = t_0 · sin(α). If the programmed roller trajectory forces a thickness deviation, unconstrained bending or material back-extrusion occurs, leading to wrinkling (if over-thick) or premature tensile necking (if over-reduced).

Multi-Pass Flow Forming: When the total desired reduction exceeds the single-pass formability limit (typically 50% for aluminum, 65% for ductile austenitic steels), multi-pass CNC roller vector trajectories with intermediate annealing stages are required. Each intermediate preform vector must maintain volumetric volume constancy.