Stamping press tonnage calculation begins by estimating the force required for the actual die operations. For blanking and piercing, this can be calculated from cutting perimeter, sheet thickness and material shear strength. For bending, drawing and complex forming, load depends more strongly on geometry, tooling method, material flow and the position of the slide through the stroke.
The calculated stamping force is only the first step in press selection. Stripping force, simultaneous stations, pressure-center location, press rating point, available energy, die cushion, shut height, bed size and off-center loading can all determine whether a nominally large enough press is actually suitable.
Dongguan Changdong Tool & Die Co., Ltd. supports DFM, CAE when required, die design and 45T–800T press tryout for suitable tooling projects. Final press requirements remain subject to the actual material, part geometry, die structure, force curve and customer production-press specifications.
Cutting load can be estimated from the active perimeter, sheet thickness and material shear strength.
Load depends on part width, thickness, material strength, radii, die geometry and the specific forming method.
Mechanical presses may provide rated tonnage only within a specified distance above bottom dead center.
A press also needs sufficient working energy and acceptable pressure-center / off-center loading conditions.
For blanking and piercing, theoretical cutting force can be estimated as cutting perimeter multiplied by sheet thickness and material shear strength. Add the forces of cutting features that act at the same time. Then separately evaluate stripping, bending, drawing and forming loads. The maximum combined force occurring at the same slide position should be compared with the press manufacturer's tonnage-versus-stroke capability, not only the nameplate tonnage. Press energy, off-center load, die size and other machine limits must also be checked.
In blanking, the required part is separated from the surrounding sheet along a closed cutting perimeter. A common preliminary force equation is:
Fcut = theoretical cutting force
L = total active cutting perimeter
t = sheet thickness
τs = material shear strength
If L and t are entered in millimeters and shear strength is entered in N/mm² (MPa), the result is in newtons.
The material input should come from an approved engineering source whenever possible. A fixed conversion from tensile strength to shear strength can be useful for early estimation, but it should not replace project-specific material data when accurate press sizing is required.
Piercing uses the same basic shear-force relationship. The difference is which material becomes the finished part and which becomes scrap.
If several holes are pierced during the same press stroke, add the perimeter of every hole that is cutting simultaneously:
In a progressive die, cutting stations may engage at different points in the stroke. The engineering objective is therefore not always to add the peak force of every station independently. The more accurate approach is to combine the station force curves at the same slide position and find the maximum total load through the stroke.
Consider a preliminary SPCC-type low-carbon steel project with the following assumed engineering inputs. The shear-strength value below is only an example for demonstrating the calculation and should not be treated as a universal SPCC specification.
| Input | Illustrative Value |
|---|---|
| Sheet thickness | 2.0 mm |
| Outer blanking perimeter | 300 mm |
| Piercing | Four Ø10 mm holes cut at the same time |
| Assumed shear strength | 300 N/mm² for this example only |
The four hole perimeters are:
The total simultaneous cutting perimeter becomes:
The theoretical cutting force is therefore:
This does not mean a nominal 30-ton press should automatically be selected. The 26-ton result represents theoretical cutting force only. Actual press selection must still consider stripping, other forming loads, engineering margin, press rating point, energy, die load distribution and machine limits.
International tooling projects often use “tons” without specifying the force unit. This can create avoidable errors.
| Force Unit | Approximate Equivalent |
|---|---|
| 1 kN | 1,000 N |
| 1 metric ton-force | 9.81 kN |
| 1 U.S. short ton-force | 8.90 kN |
RFQs and engineering calculations should therefore state whether press capacity is being discussed in kN, metric ton-force or U.S. ton-force.
After the punch penetrates the sheet, the material can grip the punch because of elastic recovery, friction, local deformation and adhesion. The stripper must remove the sheet from the punch during the return stroke.
Stripping force is sometimes estimated as a percentage of cutting force during preliminary design, but there is no single percentage that should be used for every project. Material type, thickness, punch surface, penetration, clearance, lubrication, hole density and stripper design all influence the actual requirement.
For a progressive die with many punches, stripping load may also affect spring, gas-spring or nitrogen-cylinder selection and the load applied to the press during the return portion of the cycle.
Bending is not a shearing process, so cutting perimeter multiplied by thickness and shear strength does not apply.
A general bending relationship is that required force increases with material strength, bend width and approximately the square of sheet thickness, while a larger effective die opening or span can reduce force. However, the numerical coefficient depends on the actual bending method.
This proportional relationship is useful for understanding the variables but is not a universal stamping-die design formula. V-bending, wipe bending, U-bending, flanging and restriking have different load behavior, tool geometry and contact conditions.
Deep drawing and complex automotive forming involve material flow over die radii, binder pressure, friction, work hardening and changing contact conditions. The press may experience substantial force over a much longer portion of the stroke than during a simple cutting operation.
A drawing operation can include:
forming / drawing force;
blank-holder or cushion force;
drawbead resistance;
frictional resistance;
restriking or calibration load;
additional cutting or piercing operations if integrated into the process.
For complex parts, CAE and project-specific forming calculations are more reliable than applying one generic tonnage formula. Changdong can support CAE when required during tooling development. Additional background is available in the Blank Holder Force in Deep Drawing and CAE in Stamping Die Design pages.
A progressive die can contain piercing, notching, bending, forming, restriking and cut-off stations. The press experiences all stations during the same stroke, but their peak forces may not occur at exactly the same slide position.
A more accurate engineering model therefore creates a force curve for each important station and combines them through the stroke:
The press must be evaluated against the maximum combined force at the relevant position above bottom dead center. This is especially important when high-force forming begins earlier in the stroke than the press's rated tonnage point.
A mechanical press's nominal tonnage is normally associated with a specified point close to bottom dead center. The machine does not necessarily provide the same allowable force at every point of the stroke.
This is why press manufacturers publish a rated tonnage point or a capacity curve. A die requiring high force before the press reaches its rated region can overload the mechanism even when the calculated peak force is below the number printed on the press nameplate.
Final selection should therefore use the actual press manufacturer's force-versus-stroke information rather than a generic tonnage table.
Force and energy are related but different requirements. Tonnage describes force at a given condition; energy describes the work the press can deliver through the forming portion of the stroke.
A short blanking event can create a high peak force over a very small travel. Deep drawing or large forming can require significant force over a much longer travel, creating a larger energy demand even if the maximum tonnage is similar.
Press energy should therefore be checked for long-stroke forming, high-strength material and large drawing operations. Servo and mechanical press manufacturers may publish energy-related specifications in addition to rated tonnage.
Total tonnage does not describe where the load acts. In a progressive die, several stations can create a pressure center that moves away from the physical center of the press.
Off-center loading can tilt the slide, change local die clearance and increase wear on guides and working components. The press manufacturer's allowable eccentric-load or moment limits should therefore be reviewed alongside total force.
This is especially important for long progressive dies, asymmetric trimming operations and tooling where heavy forming stations are concentrated on one end of the die.
There is no universal safety-margin percentage that should be applied to every stamping project.
A margin may be needed for uncertainty in material properties, simultaneous station loads, stripping, friction, tool wear, coil variation and calculation assumptions. However, selecting a percentage without considering the actual press rating curve and process can create a false sense of safety.
The engineering objective is to select a press with sufficient capacity under the actual force, stroke, energy and load-distribution conditions—not simply multiply the theoretical cutting force by a fixed universal factor.
The most common mistake in press sizing is to treat the theoretical force calculation as the final machine specification. Theoretical blanking tonnage describes one process load; a production press must support the entire die and process.
Correct selection asks several questions at once: How much force is required? At what slide position? For how much travel? Where is the pressure center? How much stripping or cushion force is present? Does the press have sufficient energy, bed area, shut height and die-weight capacity?
| Check | Engineering Question |
|---|---|
| Theoretical force | What are the cutting, bending, forming and stripping loads? |
| Force through stroke | Where do the maximum station loads occur relative to BDC? |
| Rated tonnage point | Does the press provide the required allowable force at the actual working position? |
| Working energy | Can the press supply enough energy over the forming travel? |
| Pressure center | Are off-center load and moment within machine limits? |
| Die cushion | Does a drawing or forming operation require cushion / blank-holder capacity? |
| Die–press interface | Do shut height, stroke, bed size, slide size and clamping match the die? |
| Feed / transfer | Does the machine provide the required feed height and automation clearance? |
For the mechanical-interface side of the review, see Die Shut Height vs Press Shut Height.
Dongguan Changdong Tool & Die Co., Ltd. supports custom stamping-die projects with DFM, CAE when required, die design, manufacturing, assembly, tryout correction and sample validation.
In-house press capacity ranges from 45T to 800T for suitable die tryout and selected stamping projects. General sheet-thickness capability is approximately 0.3–12 mm, subject to material grade, part geometry, die structure, press condition and DFM review.
These capacity figures do not mean every project within the nominal tonnage range can automatically run on every Changdong press. Final compatibility depends on the calculated force, rating point, bed dimensions, shut height, stroke, energy, off-center load and tooling conditions.
Stamping press tonnage calculation estimates the force required for a stamping die. For blanking and piercing, theoretical cutting force equals active cutting perimeter multiplied by sheet thickness and material shear strength.
Final press selection requires more than theoretical cutting tonnage. Bending, drawing, forming, stripping, rating point, working energy, pressure center, off-center loading, die cushion, shut height and machine dimensions may also control the required press.
Dongguan Changdong Tool & Die Co., Ltd. manufactures custom stamping dies and supports DFM, CAE when required and 45T–800T tooling tryout under suitable conditions. Changdong does not manufacture or sell stamping press machines, and final press selection should follow the actual press manufacturer's capacity specifications.
Theoretical blanking force is commonly estimated as cutting perimeter × sheet thickness × material shear strength. Use consistent units and the material shear strength appropriate to the actual project.
Yes, both are shearing operations and use the same basic force relationship. For several holes cut simultaneously, add their active cutting perimeters before calculating the total theoretical cutting force.
A percentage can be used for preliminary estimation, but no universal value applies to every die. Material, punch geometry, penetration, clearance, lubrication and stripping system affect the actual load.
Not automatically. The press must provide adequate allowable force at the actual point in the stroke and also satisfy energy, off-center load, bed size, shut height, stroke, die weight and other machine limits.
Complex forming force changes throughout the stroke and depends on geometry, material flow, friction, blank-holder conditions and work hardening. CAE can provide a force-vs-stroke prediction that is more useful than a single generic forming formula.
Send the part drawing, material grade, sheet thickness, expected die type and destination press specifications for a project-specific tooling and press-load review.
Email Drawings for Press-Load ReviewChangdong is good at making metal stamping dies up to 4.2 meters, also we produce small size metal stamping toolings. The company manages the complete stamping die program from the CAE Simulation, layout designs and stamping tooling designs, and finish the machining to tryout and home line tryout to your hands. Meanwhile, the company produces the prototyping parts and stamping parts range from 45-880T. The successful cases include: stamping tools of Leoni connectors, automotive stamping dies of PSA P8 & B618, metal stamping toolings of Cummins exhaust pipe assembly, automobile stamping dies of NISSAN H60B projects, and stamping tools of car audio system, Canon printers, refrigerators, ovens and washing machines and so on.If you need metal stamping dies ,stamping parts or metal prototypings,
Email to us: sales@chang-dong.com
Stamping press tonnage calculation begins by estimating the force required for the actual die operations. For blanking and piercing, this can be calculated from cutting perimeter, sheet thickness and material shear strength. For bending, drawing and complex forming, load depends more strongly on geometry, tooling method, material flow and the position of the slide through the stroke.
The calculated stamping force is only the first step in press selection. Stripping force, simultaneous stations, pressure-center location, press rating point, available energy, die cushion, shut height, bed size and off-center loading can all determine whether a nominally large enough press is actually suitable.
Dongguan Changdong Tool & Die Co., Ltd. supports DFM, CAE when required, die design and 45T–800T press tryout for suitable tooling projects. Final press requirements remain subject to the actual material, part geometry, die structure, force curve and customer production-press specifications.
Cutting load can be estimated from the active perimeter, sheet thickness and material shear strength.
Load depends on part width, thickness, material strength, radii, die geometry and the specific forming method.
Mechanical presses may provide rated tonnage only within a specified distance above bottom dead center.
A press also needs sufficient working energy and acceptable pressure-center / off-center loading conditions.
For blanking and piercing, theoretical cutting force can be estimated as cutting perimeter multiplied by sheet thickness and material shear strength. Add the forces of cutting features that act at the same time. Then separately evaluate stripping, bending, drawing and forming loads. The maximum combined force occurring at the same slide position should be compared with the press manufacturer's tonnage-versus-stroke capability, not only the nameplate tonnage. Press energy, off-center load, die size and other machine limits must also be checked.
In blanking, the required part is separated from the surrounding sheet along a closed cutting perimeter. A common preliminary force equation is:
Fcut = theoretical cutting force
L = total active cutting perimeter
t = sheet thickness
τs = material shear strength
If L and t are entered in millimeters and shear strength is entered in N/mm² (MPa), the result is in newtons.
The material input should come from an approved engineering source whenever possible. A fixed conversion from tensile strength to shear strength can be useful for early estimation, but it should not replace project-specific material data when accurate press sizing is required.
Piercing uses the same basic shear-force relationship. The difference is which material becomes the finished part and which becomes scrap.
If several holes are pierced during the same press stroke, add the perimeter of every hole that is cutting simultaneously:
In a progressive die, cutting stations may engage at different points in the stroke. The engineering objective is therefore not always to add the peak force of every station independently. The more accurate approach is to combine the station force curves at the same slide position and find the maximum total load through the stroke.
Consider a preliminary SPCC-type low-carbon steel project with the following assumed engineering inputs. The shear-strength value below is only an example for demonstrating the calculation and should not be treated as a universal SPCC specification.
| Input | Illustrative Value |
|---|---|
| Sheet thickness | 2.0 mm |
| Outer blanking perimeter | 300 mm |
| Piercing | Four Ø10 mm holes cut at the same time |
| Assumed shear strength | 300 N/mm² for this example only |
The four hole perimeters are:
The total simultaneous cutting perimeter becomes:
The theoretical cutting force is therefore:
This does not mean a nominal 30-ton press should automatically be selected. The 26-ton result represents theoretical cutting force only. Actual press selection must still consider stripping, other forming loads, engineering margin, press rating point, energy, die load distribution and machine limits.
International tooling projects often use “tons” without specifying the force unit. This can create avoidable errors.
| Force Unit | Approximate Equivalent |
|---|---|
| 1 kN | 1,000 N |
| 1 metric ton-force | 9.81 kN |
| 1 U.S. short ton-force | 8.90 kN |
RFQs and engineering calculations should therefore state whether press capacity is being discussed in kN, metric ton-force or U.S. ton-force.
After the punch penetrates the sheet, the material can grip the punch because of elastic recovery, friction, local deformation and adhesion. The stripper must remove the sheet from the punch during the return stroke.
Stripping force is sometimes estimated as a percentage of cutting force during preliminary design, but there is no single percentage that should be used for every project. Material type, thickness, punch surface, penetration, clearance, lubrication, hole density and stripper design all influence the actual requirement.
For a progressive die with many punches, stripping load may also affect spring, gas-spring or nitrogen-cylinder selection and the load applied to the press during the return portion of the cycle.
Bending is not a shearing process, so cutting perimeter multiplied by thickness and shear strength does not apply.
A general bending relationship is that required force increases with material strength, bend width and approximately the square of sheet thickness, while a larger effective die opening or span can reduce force. However, the numerical coefficient depends on the actual bending method.
This proportional relationship is useful for understanding the variables but is not a universal stamping-die design formula. V-bending, wipe bending, U-bending, flanging and restriking have different load behavior, tool geometry and contact conditions.
Deep drawing and complex automotive forming involve material flow over die radii, binder pressure, friction, work hardening and changing contact conditions. The press may experience substantial force over a much longer portion of the stroke than during a simple cutting operation.
A drawing operation can include:
forming / drawing force;
blank-holder or cushion force;
drawbead resistance;
frictional resistance;
restriking or calibration load;
additional cutting or piercing operations if integrated into the process.
For complex parts, CAE and project-specific forming calculations are more reliable than applying one generic tonnage formula. Changdong can support CAE when required during tooling development. Additional background is available in the Blank Holder Force in Deep Drawing and CAE in Stamping Die Design pages.
A progressive die can contain piercing, notching, bending, forming, restriking and cut-off stations. The press experiences all stations during the same stroke, but their peak forces may not occur at exactly the same slide position.
A more accurate engineering model therefore creates a force curve for each important station and combines them through the stroke:
The press must be evaluated against the maximum combined force at the relevant position above bottom dead center. This is especially important when high-force forming begins earlier in the stroke than the press's rated tonnage point.
A mechanical press's nominal tonnage is normally associated with a specified point close to bottom dead center. The machine does not necessarily provide the same allowable force at every point of the stroke.
This is why press manufacturers publish a rated tonnage point or a capacity curve. A die requiring high force before the press reaches its rated region can overload the mechanism even when the calculated peak force is below the number printed on the press nameplate.
Final selection should therefore use the actual press manufacturer's force-versus-stroke information rather than a generic tonnage table.
Force and energy are related but different requirements. Tonnage describes force at a given condition; energy describes the work the press can deliver through the forming portion of the stroke.
A short blanking event can create a high peak force over a very small travel. Deep drawing or large forming can require significant force over a much longer travel, creating a larger energy demand even if the maximum tonnage is similar.
Press energy should therefore be checked for long-stroke forming, high-strength material and large drawing operations. Servo and mechanical press manufacturers may publish energy-related specifications in addition to rated tonnage.
Total tonnage does not describe where the load acts. In a progressive die, several stations can create a pressure center that moves away from the physical center of the press.
Off-center loading can tilt the slide, change local die clearance and increase wear on guides and working components. The press manufacturer's allowable eccentric-load or moment limits should therefore be reviewed alongside total force.
This is especially important for long progressive dies, asymmetric trimming operations and tooling where heavy forming stations are concentrated on one end of the die.
There is no universal safety-margin percentage that should be applied to every stamping project.
A margin may be needed for uncertainty in material properties, simultaneous station loads, stripping, friction, tool wear, coil variation and calculation assumptions. However, selecting a percentage without considering the actual press rating curve and process can create a false sense of safety.
The engineering objective is to select a press with sufficient capacity under the actual force, stroke, energy and load-distribution conditions—not simply multiply the theoretical cutting force by a fixed universal factor.
The most common mistake in press sizing is to treat the theoretical force calculation as the final machine specification. Theoretical blanking tonnage describes one process load; a production press must support the entire die and process.
Correct selection asks several questions at once: How much force is required? At what slide position? For how much travel? Where is the pressure center? How much stripping or cushion force is present? Does the press have sufficient energy, bed area, shut height and die-weight capacity?
| Check | Engineering Question |
|---|---|
| Theoretical force | What are the cutting, bending, forming and stripping loads? |
| Force through stroke | Where do the maximum station loads occur relative to BDC? |
| Rated tonnage point | Does the press provide the required allowable force at the actual working position? |
| Working energy | Can the press supply enough energy over the forming travel? |
| Pressure center | Are off-center load and moment within machine limits? |
| Die cushion | Does a drawing or forming operation require cushion / blank-holder capacity? |
| Die–press interface | Do shut height, stroke, bed size, slide size and clamping match the die? |
| Feed / transfer | Does the machine provide the required feed height and automation clearance? |
For the mechanical-interface side of the review, see Die Shut Height vs Press Shut Height.
Dongguan Changdong Tool & Die Co., Ltd. supports custom stamping-die projects with DFM, CAE when required, die design, manufacturing, assembly, tryout correction and sample validation.
In-house press capacity ranges from 45T to 800T for suitable die tryout and selected stamping projects. General sheet-thickness capability is approximately 0.3–12 mm, subject to material grade, part geometry, die structure, press condition and DFM review.
These capacity figures do not mean every project within the nominal tonnage range can automatically run on every Changdong press. Final compatibility depends on the calculated force, rating point, bed dimensions, shut height, stroke, energy, off-center load and tooling conditions.
Stamping press tonnage calculation estimates the force required for a stamping die. For blanking and piercing, theoretical cutting force equals active cutting perimeter multiplied by sheet thickness and material shear strength.
Final press selection requires more than theoretical cutting tonnage. Bending, drawing, forming, stripping, rating point, working energy, pressure center, off-center loading, die cushion, shut height and machine dimensions may also control the required press.
Dongguan Changdong Tool & Die Co., Ltd. manufactures custom stamping dies and supports DFM, CAE when required and 45T–800T tooling tryout under suitable conditions. Changdong does not manufacture or sell stamping press machines, and final press selection should follow the actual press manufacturer's capacity specifications.
Theoretical blanking force is commonly estimated as cutting perimeter × sheet thickness × material shear strength. Use consistent units and the material shear strength appropriate to the actual project.
Yes, both are shearing operations and use the same basic force relationship. For several holes cut simultaneously, add their active cutting perimeters before calculating the total theoretical cutting force.
A percentage can be used for preliminary estimation, but no universal value applies to every die. Material, punch geometry, penetration, clearance, lubrication and stripping system affect the actual load.
Not automatically. The press must provide adequate allowable force at the actual point in the stroke and also satisfy energy, off-center load, bed size, shut height, stroke, die weight and other machine limits.
Complex forming force changes throughout the stroke and depends on geometry, material flow, friction, blank-holder conditions and work hardening. CAE can provide a force-vs-stroke prediction that is more useful than a single generic forming formula.
Send the part drawing, material grade, sheet thickness, expected die type and destination press specifications for a project-specific tooling and press-load review.
Email Drawings for Press-Load ReviewDongguan Changdong Stamping Dies CO., LTD. © copyright Add：NO. 56-B, Fuming South Road, Dalang, Dongguan, P.R.C
E-mail: sales@chang-dong.com Tel: 0086-769-8106 1256 Mobile: 0086-189 2949 4380 Sales Manager: Ms. Alice Fax: 0086-769-8106 1926
Dongguan Changdong Tool & Die Co., Ltd. is a custom metal stamping die and stamped parts manufacturer founded in 2012. We support automotive, home appliance, electrical and industrial projects from DFM review and die design to press tryout, sample validation and metal stamping production.
Main capabilities: Stamping Dies | Progressive Die | Transfer Die | Prototype Die | Prototype Tooling | Stamping Parts | Custom Metal Stamping Parts
For new tooling or stamping projects, please send your 2D drawing, 3D model, material grade, sheet thickness, tolerance requirements, annual volume and sample target date through Contact Us.
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