Understanding how to calculate and select the correct power press tonnage helps avoid equipment overload, mold damage, and production inefficiencies.
This guide provides a clear explanation of what power press tonnage is, how to calculate it, what factors influence your choice, etc.
What is Power Press Machine Tonnage
Power press machine tonnage refers to the maximum pressure that a press can apply in operations such as metal processing, stamping, and bending. This parameter is an important indicator for measuring the capacity of a press, usually expressed in tons or kilonewtons (kN).
The tonnage range of power press machines is very wide. For example, the tonnage range of World’s C frame mechanical power press is 6.3-400 tons, the tonnage range of H frame mechanical power press is 80-800 tons, the tonnage range of hydraulic power press is 10-5000 tons, and the tonnage range of heavy mechanical power press is 125-2000 tons.
Power Press Tonnage Calculation Formula
If other factors are not considered (such as material thickness, type, bending angle, shape and size of stamping tool, etc.), Power Press Tonnage = 1.3 × Workpiece Size × Workpiece Thickness × Material shear strength / 10000
“1. 3” is a safety factor that takes into account factors such as die wear and uneven material properties to ensure the safety of the stamping process. In actual calculations, the value is usually 1.3 to prevent equipment damage or operation failure due to calculation errors or unexpected situations.
The “workpiece size” here usually refers to the circumference of the stamping part, that is, the total length of the contour of the blanked part.
The “workpiece thickness (t)” refers to the thickness of the processed material, in millimeters (mm). The greater the thickness, the greater the force required for stamping, because greater material resistance needs to be overcome.
The “shear strength (τ) of the material” is the maximum stress that the material can withstand when subjected to shear force, in megapascals (MPa) or N/mm². It reflects the strength characteristics of the material under shear. The higher the shear strength, the less likely the material is to deform, so a greater punching force is required.
The step of dividing by 10,000 (“/10000”) converts the result from Newtons (N) to tons (tons). 1 ton equals 9,806 Newtons, so you need to divide by an approximate value (such as 10,000) to complete the unit conversion.
Shear Strength of Common Metals
| Material Example | Shear Strength (MPa or N/mm²) | Shear Strength (psi) |
| Low Carbon Steel (A36, Fe37) | 285–390 | 41,000–56,000 |
| High-Strength Steel (A588) | 300–340 | 44,000–49,000 |
| Alloy Steel (quenched/tempered) | 485–630+ | 70,000–91,000+ |
| Stainless Steel (304, 316) | 517–620 | 75,000–90,000 |
| Spring Steel (hardened) | 1,380 | 200,000 |
| Aluminum Alloys | 62–331 | 9,000–48,000 |
| 6061-T6 Aluminum | 207 | 30,000 |
| 7075-T6 Aluminum | 331 | 48,000 |
| Pure Copper | 152–240 | 22,000–35,000 |
| Brass (various tempers) | 234–420 | 34,000–61,000 |
| Titanium (unalloyed) | 345 | 50,000 |
| Titanium Alloys (e.g., Ti-6Al-4V) | 550–800+ | 80,000–116,000+ |
What Factors Affect the Selection of Power Press Machine Tonnage?
The thickness of the material directly affects the tonnage required for the press. For example, for thinner materials, a smaller power press machine tonnage will suffice, while thicker materials require a larger tonnage power press machine.
The type of material (e.g., steel, aluminum, copper, etc.) also affects its shear strength, which in turn affects the tonnage required for the press. High-strength materials such as stainless steel require higher punching forces than copper.
The size and shape of the workpiece will affect the tonnage required for the power press. For example, larger workpieces require larger worktables and higher opening heights, while requiring more tonnage to handle greater material thickness and weight.
The complexity of the stamping process will also affect the tonnage requirements. For example, complex processes such as deep drawing, bending, or forming require higher tonnage to provide sufficient pressure.
Production efficiency, for example, the speed and frequency of the presses will also affect the tonnage requirements. High-speed production requires higher tonnage to ensure that the required force is achieved with each press, while low-speed production may require lower tonnage.
The power press machine tonnage must be matched to the size and design of the die. If the mold size is large, a larger tonnage power press machine is required to ensure the normal operation of the mold.
Tonnage Selection Recommendations
The following are the tonnage selection recommendations for different models of World Group power presses for your reference:
If the processing accuracy is not high, the product size is not large, and the batch is large, we recommend JH21 (25- 400 tons). It is especially suitable for processing small parts such as small hardware and home appliance accessories.
If you are processing large workpieces that require high precision, the high-strength, good rigidity JW36 (110- 630 tons) can meet your needs.
JS39 (400- 2000 tons) is a four-point power press, which is more suitable for oversized, high-precision, high-tonnage products, and supports multi-station stamping and automated intelligent production.
How to Choose the Most Suitable Power Press Machine Tonnage?
The first step in choosing the most suitable power press machine tonnage is to determine the product to be processed.
Users need to make demands to the mold manufacturer based on the specific size, structural complexity, wall thickness and other parameters of their products.
Mold manufacturers can preliminarily determine the required power press machine tonnage by designing molds based on product structure, materials and production processes.
Importance of Choosing the Right Power Press Machine Tonnage
1. The right tonnage ensures that the force applied by the press during processing is sufficient to complete the required bending or forming operation, while avoiding deformation or breakage of the material due to insufficient force. Insufficient tonnage will result in incomplete bending or material damage, while too high tonnage may cause excessive deformation of the material or damage to the mold.
2. The correct tonnage selection not only affects product quality, but also directly affects production efficiency and equipment life. If the tonnage is too high, the equipment will accelerate wear due to overload and increase maintenance costs; if the tonnage is too low, it may cause frequent start and stop of the equipment, reducing production efficiency.
3. Incorrect tonnage selection may bring serious safety hazards. For example, too high tonnage may cause mold breakage or equipment damage, or even cause safety accidents. Too low tonnage may not be able to complete the task, forcing the operator to intervene manually, increasing operational risks.
4. Choosing the right tonnage can effectively reduce energy consumption and production costs. If the tonnage is too high, the equipment will consume more energy during processing, increasing electricity and maintenance costs. If the tonnage is too low, it may cause the equipment to run for a long time, be inefficient, and also increase costs.
5. Choosing the right tonnage can ensure that the equipment can operate efficiently under different process conditions and meet diverse needs. Different materials and processes have different requirements for tonnage. For example, thicker or harder materials require higher tonnage, while thinner or softer materials require lower tonnage. In addition, different bending angles and lengths will also affect the tonnage.
6. Choosing the right tonnage can not only protect molds and tools, but also reduce the frequency of replacement and reduce maintenance costs. Too high tonnage will accelerate the wear of molds and tools and shorten their service life.
