BIZOMAT MAKEOS · Fabrication
Shear Spun Cone Plan (Blank, Reduction, Roller Force, Power, Time)
What blank do I need to shear spin this cone, is the thickness reduction within what the material will take, and is the lathe powerful enough?
Plan for shear spinning a cone: blank thickness by the sine law and the thickness reduction (as the shear spinning tool) against the largest reduction the material will take in one pass, blank diameter and mass, tangential roller force, surface speed and power at the roller against the machine, and the spinning time over the cone length at the roller feed.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Wall thickness of the spun cone | mm | Wall thickness the spun cone must have. |
| Half angle of the cone | ° | Half angle of the cone measured from its axis. |
| Large diameter of the cone | mm | Diameter of the large end of the cone (the blank diameter in shear spinning). |
| Small diameter of the cone | mm | Diameter of the small end where the cone meets the mandrel nose. |
| Average flow stress of the material | MPa | Average flow stress of the material over the reduction. |
| Material density | kg/m³ | Density of the material. |
| Process and limits | ||
| Roller feed per revolution | mm/rev | Axial feed of the roller per spindle revolution. |
| Spindle speed | rpm | Spindle speed. |
| Largest reduction in one pass | % | Largest thickness reduction the material takes in one pass (from your spinning trials). |
| Machine power at the spindle | kW | Power available at the spindle. |
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 cone
- What it is
- The finished wall thickness of the cone after shear spinning, measured square to the 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
- The blank thickness is this thickness divided by the sine of the half angle.
What this means: Half angle of the cone
- What it is
- The half angle of the cone: the angle between the cone wall and the cone 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 a larger reduction.
- Get it right
- Use the half angle from the axis, not the included angle across the cone.
What this means: Large diameter of the cone
- What it is
- The diameter of the large, open end of the cone. In shear spinning the blank diameter equals this diameter, so it also sets the blank mass.
- 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 300 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Sets the surface speed and power at the roller, the blank mass and, with the small diameter, the cone length.
What this means: Small diameter of the cone
- What it is
- The diameter of the small end of the cone, where the wall meets the mandrel nose.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 5000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 100 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Used only for the cone axial length and the spinning time.
What this means: Average flow stress of the material
- What it is
- The average flow stress of the blank material over the thickness reduction it undergoes, from material test data or the supplier.
- 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
- The roller force and power rise in proportion to it.
- Get it right
- Flow stress during deformation is higher than the yield strength of annealed stock.
What this means: Material density
- What it is
- The density of the blank material, used only to work out the blank mass.
- Units and format
- Enter a number in kg/m³: kilograms per cubic metre. The form accepts 0.000001 kg/m³ to 20000 kg/m³. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2700 kg/m³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- This is in kilograms per cubic metre.
Process and limits
What this means: Roller feed per revolution
- What it is
- How far the roller advances along the cone axis for each 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
- A higher feed raises the roller force and power and shortens the spinning time.
- Get it right
- Per revolution, not per minute.
What this means: Spindle speed
- What it is
- The rotational speed of the mandrel and blank during spinning.
- 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
- Higher speed raises the surface speed and power and shortens the spinning time.
What this means: Largest reduction in one pass
- What it is
- The largest thickness reduction the material will take in a single pass without cracking, from your own spinning trials or the material supplier.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 1% to 95%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 70% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Type the percentage; reduction is 1 − finished thickness ÷ blank thickness.
What this means: Machine power at the spindle
- What it is
- The power available at the spindle of the spinning machine, from its rating plate or the maker’s data.
- Units and format
- Enter a number in kW: kilowatts. The form accepts 0.000001 kW to 100000 kW. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 5 kW as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use spindle power, not the motor input power.
Method and formulas
- Blank thickness T = t ÷ sin α; reduction = 1 − t ÷ T (as the shear spinning tool).
- Tangential force = flow stress × (T − t) × feed; power = force × surface speed at the large diameter (as the shear spinning tool).
- Blank diameter = large cone diameter; cone axial length = (D_l − D_s) ÷ 2 tan α; time = length ÷ (feed × rpm).
- Example: use a 4 mm blank 300 mm across (0.76341 kg); reduction 50%; 1.885 kW; 51.962 s to spin.
Limitations
- Ideal sine-law deformation; real forces include friction and redundant work.
- Single pass; larger reductions need intermediate annealing or two passes.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Plan the blank for a spun cone
- Check whether a cone can be spun in one pass
- Estimate the spinning time and power
Who it is for
- Metal spinners
- Fabrication engineers
- Process planners
What you get
- Blank thickness, diameter and mass
- Reduction against the limit
- Roller force, power and spinning time
Interpreting the result
- Small cone angles need very thick blanks and large reductions: they may need two passes.
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 Spun Cone Plan (Blank, Reduction, Roller Force, Power, Time) calculator