BIZOMAT MAKEOS · Fabrication
Guillotine Shear Check (Cutting Force, Energy, Power, Thickest Sheet)
Can this guillotine shear cut my sheet: what force and energy does each cut take, does the motor keep up at my stroke rate, and what is the thickest sheet it can cut in this material?
Check of a sheet-metal guillotine with a raked (inclined) or parallel blade: shearing force and the machine force with the 1.3 allowance (as the shearing blade force tool), energy per cut from the force for parallel blades over the penetration, motor power at the stroke rate and drive efficiency, the sheet width against the blade length, and the thickest sheet the machine capacity allows in this material at this rake.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Blade arrangement | choice | Raked blades cut progressively with less force; parallel blades cut the whole width at once. |
| Sheet thickness | mm | Thickness of the sheet. |
| Width of cut | mm | Width of sheet cut. |
| Shear strength of the sheet | MPa | Shear strength of the sheet (about 0.75–0.8 of tensile strength for steels). |
| Tensile strength of the sheet | MPa | Tensile strength of the sheet. |
| Rake angle | ° | Rake angle of the moving blade. |
| Penetration coefficient | Penetration coefficient in the inclined-blade formula (handbook value for the material; your value). | |
| Strength ratio factor | Ratio factor in the inclined-blade formula (your value). | |
| Relative penetration at fracture | Share of the thickness the blade enters before the sheet fractures. | |
| Machine force capacity | kN | Rated cutting force of the machine. |
| Blade length | mm | Length of the blade. |
| Cuts per minute | Number of cuts per minute. | |
| Motor power | kW | Rated power of the main motor. |
| Drive efficiency | % | Share of motor power reaching the blade. |
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: Blade arrangement
- What it is
- Whether the moving blade is raked (inclined), cutting progressively along the sheet, or parallel to the fixed blade, cutting the whole width at once. It selects the force formula.
- Units and format
- Choose one of 2 options from the list: Inclined (raked) blade; Parallel blades.
- Example
- The form opens with “Inclined (raked) blade” selected as a worked example. Choose the option that matches your case.
What this means: Sheet thickness
- What it is
- The thickness of the sheet being cut, measured with a micrometer or taken from the material certificate.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 50 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- With a raked blade the force rises with the square of thickness; with parallel blades it rises in direct proportion.
What this means: Width of cut
- What it is
- The length of the cut across the sheet. It must fit within the blade length and sets the energy per cut.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1000 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- For parallel blades the force rises in proportion; the raked-blade force does not depend on it.
What this means: Shear strength of the sheet
- What it is
- The ultimate shear strength of the sheet material, from its data sheet. It sets the force for parallel blades and the energy per cut for both blade types.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 2000 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.
What this means: Tensile strength of the sheet
- What it is
- The ultimate tensile strength of the sheet material, from the material certificate. It is used only in the raked-blade force formula.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 2500 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 400 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Rake angle
- What it is
- The angle between the moving blade and the fixed blade, which spreads the cut along the sheet. Used only for the raked blade.
- Units and format
- Enter a number in °: degrees of angle. The form accepts 0.5° to 10°. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2° as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger rake lowers the cutting force, which varies with 1 ÷ tan α.
What this means: Penetration coefficient
- What it is
- The penetration coefficient in the handbook raked-blade formula for the sheet material, from the handbook or your own trials.
- Units and format
- Enter a plain number with no unit. The form accepts 0.3 to 1. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.8 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Used only for the raked blade.
What this means: Strength ratio factor
- What it is
- The strength ratio factor in the handbook raked-blade formula, a value you supply from the handbook or your experience.
- Units and format
- Enter a plain number with no unit. The form accepts 0.3 to 1. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.75 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Used only for the raked blade.
What this means: Relative penetration at fracture
- What it is
- The share of the sheet thickness the blade penetrates before the sheet fractures. It enters the raked-blade force and the energy per cut.
- Units and format
- Enter a plain number with no unit. The form accepts 0.1 to 1. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.6 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Enter it as a fraction of the thickness, not as a percentage.
What this means: Machine force capacity
- What it is
- The rated cutting force of the machine from its nameplate or manual, compared with the cutting force including the 1.3 allowance.
- Units and format
- Enter a number in kN: kilonewtons (1 kN = 1000 N). The form accepts 0.000001 kN to 100000 kN. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 300 kN as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Blade length
- What it is
- The usable length of the guillotine blade, compared with the width of cut.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2500 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Cuts per minute
- What it is
- How many cuts the machine makes each minute, used to turn energy per cut into average power.
- Units and format
- Enter a plain number with no unit. The form accepts 0 to 200. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 20 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The power needed rises in direct proportion.
What this means: Motor power
- What it is
- The rated power of the main motor from its nameplate, compared with the average power the cuts need.
- Units and format
- Enter a number in kW: kilowatts. The form accepts 0.000001 kW to 10000 kW. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 5.5 kW as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Drive efficiency
- What it is
- The share of motor power that reaches the blade after losses in belts, flywheel, gears or hydraulics.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 20% to 100%. 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.
- Effect on the result
- Lower efficiency raises the motor power needed.
Method and formulas
- Parallel blades F = τ b T; inclined blades F = n k UTS ε T² ÷ tan α; machine force = 1.3 F (as the shearing blade force tool).
- Energy per cut ≈ τ b T × ε T (the shearing work is the same whatever the rake); power = energy × cuts per minute ÷ 60 ÷ efficiency.
- Thickest sheet at capacity: inclined T = √[cap tan α ÷ (1.3 n k UTS ε)]; parallel T = cap ÷ (1.3 τ b).
- Example: 3 mm × 1000 mm needs 48.246 kN (capacity 300 kN), 1,620 J per cut and 0.77143 kW at 20 cuts a minute; the thickest sheet is 7.4808 mm.
Limitations
- Handbook approximate formulas; blade clearance and sharpness change the force.
- Flywheel machines can exceed the average power for single cuts.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check whether a shear can cut a thicker or stronger plate
- Estimate motor power for a shearing rate
- Choose rake for a thick sheet
Who it is for
- Fabrication supervisors
- Press and shear operators
- Manufacturing engineers
What you get
- Shearing and machine force against capacity
- Energy per cut and power at the stroke rate
- Thickest sheet at capacity and width check
Interpreting the result
- More rake lowers the force but twists and bows the cut strip: thick plate is cut at the smallest rake that the capacity allows.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1336–1338. Topic reference; no source tables or recommended settings are reproduced.
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Open the Guillotine Shear Check (Cutting Force, Energy, Power, Thickest Sheet) calculator