If you decide to purchase press brake from China, the following press brake tonnage calculator (metric, in mm) and press brake bending (tonnage) chart will help you make the better decision for choosing suitable brake press machine.
Press Brake Tonnage Chart
Note: if there are no special requirements for bending radius, the slot width V should be 8-10 times plate thickness.
The above tonnage on press brake tonnage chart is calculated according to the plate tensile strength σb=450N/mm² and length L=1m
For steel with different strength, the force required to bend steel plate can be calculated according to below sheet metal bending force calculation formula:
- P: bending force (KN)
- S: plate thickness (mm)
- L: plate width (m)
- V: bottom die slot width (mm)
Plate thickness S=4mm, width L=3m, σb=450N/mm²
Generally slot width V=S*8
Therefore P=650*4²*3/4*8=975 (KN) = 99.5 (Ton)
Press Brake Tonnage Calculator Metric
Find tonnage on the chart
If directly check via the above chart, first find plate thickness S=4mm on the left side, and then find the slot width V=4*8=32mm on the first line, you get the data 330, which is the bending press fothe r 1m plate. For 3 meters plate, the bending tonnage P=330*3=990 (KN)=101 (Ton), close to the result calculated according to the formula.
Here we come to the conclusion: you should choose at least 100ton press brake.
There is one similar press brake bending chart made by one European professional press brake toolings manufacturer, below is it:
According to my above explanation, you can easily find the right tonnage of press brake that you required.