BIZOMAT MAKEOS · Fabrication
Shear Spinning Blank Thickness and Force
How thick must the blank be for this shear-spun cone, and what force and power does the roller need?
Shear (cone) spinning by the sine law: starting blank thickness for a required wall thickness and cone half-angle, the ideal tangential roller force from the material’s average flow stress, thickness reduction and feed, and the power at the roller.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Wall thickness of the spun part | mm | Required wall thickness of the cone. |
| Half angle of the cone | ° | Half angle of the cone (between the wall and the axis). |
| Average flow stress of the material | MPa | Average flow stress over the strain range (from a true stress–strain calculation). |
| Roller feed per revolution | mm/rev | Axial feed of the roller per revolution. |
| Diameter at the roller | mm | Work diameter at the roller contact. |
| Spindle speed | rpm | Spindle speed. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Wall thickness of the spun part
- What it is
- The wall thickness the finished spun cone must have, measured square to the cone wall.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Blank thickness is T_w ÷ sin α, so it scales directly with the wall thickness.
- Get it right
- Measure normal to the wall, not along the axis.
What this means: Half angle of the cone
- What it is
- The half angle of the finished cone: the angle between the cone wall and the spindle axis.
- Units and format
- Enter a number in °: degrees of angle. The form accepts 5° to 89°. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 30° as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A smaller half angle needs a thicker blank and more thickness reduction, since T = T_w ÷ sin α.
- Get it right
- Half angle, not the included angle of the cone.
What this means: Average flow stress of the material
- What it is
- The average true stress the material needs to keep deforming over the strain range of the spinning pass, from a true stress–strain curve or material data.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 3000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 300 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Roller force and power are directly proportional to it.
- Get it right
- Use the average flow stress over the strain range, not the yield strength at the start of deformation.
What this means: Roller feed per revolution
- What it is
- How far the roller advances along the cone axis in one spindle revolution.
- Units and format
- Enter a number in mm/rev: millimetres per revolution. The form accepts 0.000001 mm/rev to 10 mm/rev. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.5 mm/rev as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Roller force and power rise in direct proportion to the feed.
- Get it right
- Axial feed per revolution, not per minute.
What this means: Diameter at the roller
- What it is
- The work diameter where the roller is in contact, which sets the surface speed for the power estimate.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 200 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Power rises in proportion to this diameter; blank thickness and force do not depend on it.
- Get it right
- The diameter changes along the cone; use the largest one in the pass for the highest power.
What this means: Spindle speed
- What it is
- The rotational speed of the spindle and mandrel during the spinning pass.
- Units and format
- Enter a number in rpm: revolutions per minute. The form accepts 0.000001 rpm to 100000 rpm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 400 rpm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Power rises in proportion to speed; force and blank thickness are unchanged.
Method and formulas
- Sine law: T = T_w ÷ sin α (the flange keeps its blank diameter, the wall thins).
- Ideal tangential force F_t = σ_f (T − T_w) f.
- Power = F_t × surface speed at the roller.
- Example: a 2 mm wall at 30° half angle needs a 4 mm blank.
Limitations
- Ideal force; friction and redundant work add to it.
- Very small half angles exceed the material’s spinnability limit; confirm with trials.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Choose blank thickness for a spun cone
- Estimate roller force and machine power
- Check how steep a cone can be spun in one pass
Who it is for
- Forming engineers
- Spinning machine operators
- Manufacturing engineers
What you get
- Starting blank thickness
- Tangential roller force
- Power at the roller
Interpreting the result
- Thickness reduction (1 − sin α) is the measure of severity; stay within the material’s tested limit.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1362–1364. Topic reference; no source tables or recommended settings are reproduced.
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Open the Shear Spinning Blank Thickness and Force calculator