Master the Ultimate Guide to Calculate Punching Force
In this article, I’ll guide you through how to calculate punching force effectively. Understanding this crucial aspect is essential for optimizing your manufacturing processes. Whether you’re working with various materials or different machine specifications, knowing how to determine the appropriate punching force can significantly impact productivity and quality. I’ll share practical tips and formulas to help you make accurate calculations, ensuring that your operations run smoothly and efficiently. Let’s delve into the details and enhance your understanding of this vital topic!
Click above picture to use Punching force calculator
Calculate Punching Force Formula
If you punch round holes or square holes, or some other forms of holes through a given thickness of metal, you must know the force required to punch a hole in steel. You can calculate the punching tonnage been required with the help of the following punching force calculation formula (blanking force formula):
K : Safety factor, usually we will choose 1.3
L : Perimeter after punching , mm
t : Material thickness, mm
τ : Shear strength, MPa
If we want to converted the result into metric tons, we can divide the result of KN by 9.8
We can calculate the perimeter refering to the following chart
Thickness: the thickness is for the material which will be pierced through by the punching mold.
Shear strength: the physical properties of the plate, determined by the material of the sheet and can be found in the material manual.
The following chart is showing the shear strength for usual material:
Unit:kN/mm2
For example:
If we will punch one square hole in the 3mm thickness, the material is low-carbon steel plate, side length is 20mm, we can calculate punching force in this way:
Perimeter=10*4=40mm
Thickness=3mm
Shear strength=0.3447kN/mm2
Punch force(kn)=1.3*40*3*0.3447=53.77kN
W can convert it into tonnage :107.55kN/9.8=5.49T
Punch and die clearance
The clearance between punch and die is represented by the total difference, which is one of the critical factors in the punching process.
For example, when use ∅12.25 lower die, the optimal clearance is 0.25mm.
Improper clearance will reduce the die service life, or burrs and lead to secondary cutting, the irregular opening will increase the demounting force, etc.
Besides, the die clearance is subject to the material and thickness, generally, for carbon steel plate,12%-18% of the thickness is best.
If no special requirements in CNC punch, you can refer to the following table for selecting the die clearance:
| Plate Thickness | Material | ||
| Medium Carbon Steel | Aluminum | Stainless Steel | |
| 0.8-1.6 | 0.15-0.2 | 0.15-0.2 | 0.15-0.3 |
| 1.6-2.3 | 0.2-0.3 | 0.2-0.3 | 0.3-0.4 |
| 2.3-3.2 | 0.3-0.4 | 0.3-0.4 | 0.4-0.6 |
| 3.2-4.5 | 0.4-0.6 | 0.4-0.5 | 0.6-1.0 |
| 4.5-6.0 | 0.6-0.9 | 0.5-0.7 | – |
