Hydraulic Press Tonnage Calculator
Estimate cylinder tonnage, required forming or cutting load, tooling stress, pressure demand, and frame margin for shop presses, H-frame presses, and production press setups.
Formula Breakdown
| Press preset | Typical frame | Bore and pressure | Common check |
|---|---|---|---|
| 10 ton bench press | 10 short tons | 3 in bore at 2800 psi | Small pins, bushings, light forming |
| 20 ton shop press | 20 short tons | 4 in bore at 2500 psi | Axle pins, bearing removal, straightening |
| 50 ton H-frame | 50 short tons | 5 in bore at 3000 psi | Short plate bends and heavy press fits |
| 100 ton production press | 100 short tons | 7 in bore at 3200 psi | Strip shearing, punching, forming |
| 200 ton four-post press | 200 short tons | 9 in bore at 3500 psi | Large tooling with guided platen |
| Material | Yield strength | Shear estimate | Press note |
|---|---|---|---|
| 6061-T6 aluminum | 40,000 psi | 23,200 psi | Lower tonnage, watch galling |
| Mild steel A36 | 36,000 psi | 20,880 psi | Baseline shop steel |
| 304 stainless | 42,000 psi | 24,360 psi | High springback and work hardening |
| Cartridge brass | 45,000 psi | 26,100 psi | Clean cuts with sharp tooling |
| O1 tool steel | 90,000 psi | 52,200 psi | Check die strength carefully |
| Mode | Calculator formula | Best input to measure | Watch item |
|---|---|---|---|
| Air bend | 1.33 x yield x length x thickness² / die opening | Bend length and V opening | Die width and springback |
| Punch | Perimeter x thickness x shear strength | Total cutting perimeter | Punch buckling and stripper load |
| Straight shear | Cut length x thickness x shear strength x rake factor | Full shear line length | Blade clearance and hold-downs |
| Press-fit | Yield x contact area x 0.65 | Projected contact area | Part support and alignment |
| Cylinder bore | Ram area | Force at 2500 psi | Force at 3000 psi |
|---|---|---|---|
| 3 in | 7.07 in² | 8.8 tons | 10.6 tons |
| 4 in | 12.57 in² | 15.7 tons | 18.8 tons |
| 5 in | 19.63 in² | 24.5 tons | 29.5 tons |
| 6 in | 28.27 in² | 35.3 tons | 42.4 tons |
| 8 in | 50.27 in² | 62.8 tons | 75.4 tons |
Hydraulic press can convert the pressures from the pump into a force. A hydraulic press will convert that pressure into a specific amount of tonnage. You must determine the amount of tonnage that are required for teh job.
Using the wrong amount of tonnage for a job will damage the hydraulic press or the tooling on the press. A low amount of tonnage is required for light jobs. A high amount of tonnage is required for jobs that involves thick plate or stock.
How to Choose the Right Tonnage for a Hydraulic Press
The amount of tonnage that you should use will keep the tooling intact, keep the frame of the press unbent, and keep the operator safe from the ejection path of the press. The bore of the press cylinder and the system pressure determine the maximum force that can be produced by the hydraulic press. The frame of the press limits the maximum force that can be produced.
The area of contact between the tooling and the work piece determine how the press distributes the force to the work piece. Using a small pad to distribute the force of a large ram can produce stresses on the work piece that are more greater than the yield strength of the material. The thickness and length of the work piece will also affect the force that is required to complete the job.
The longer and thicker the work piece, the greater the force that is required to perform the task. These measurements must be entered into the hydraulic press tonnage calculator because the calculator require these measurements to perform its calculations. The material that is to be cut will affect the calculations that the calculator performs.
The force requirement for the job will change based off the material that is to be cut. The yield strength of the material sets the parameter for the calculations of the tonnage that is required for bending operations. The yield strength of the material is also the value that is used to calculate the shear strength of the material.
Materials with high yield strength include mild steel. Other materials with high strength include stainless steel and tool steel. The preset material button is include in the calculator to make it easier for the operator to avoid treating all materials as the same.
A safety factor must be included in the calculations to ensure the best result in the shop. A safety factor of 1.25 is sufficient for work setups that is rigid and with sharp tooling. A safety factor of 1.5 is better for most work situation in the shop.
Most machine operators use a safety factor of 2.0 or higher when the property of the material are not certain or when cutting prototypes. The safety factor that is calculated will be multiplied by the calculated force to determine the total force that will be place into the work piece. Using a higher safety factor will reduce the working margin of the press.
However, using a higher safety factor will also provide a buffer to absorb unexpected force on the work piece. The reference tables provided on this page will help to give you starting point for your work. However, they will not replace the need for actual measurements of the work piece.
These tables will provide examples of the maximum force of hydraulic presses with specific bore size and system pressure. The tables will also provide the yield strength of the materials. Relying only on the reference tables will produce incorrect assumption for your work.
However, using the tables will help you to reduce the chance of making such incorrect assumption. The hydraulic press has limit that are outside of the parameters of the hydraulic press tonnage calculator. The calculator cannot determine the deflection of the press columns, the condition of the hose, the wear of the pin or the platen parallelism.
The status output will let the operator know if the required force is close to the limit of the cylinder or frame of the press. However, the status output only apply to when the hydraulic press is in good condition. Regular inspection of the press are required to ensure that the hydraulic press continues to remain in good working condition and that the operator does not exceed the limit of the press.
The number should be entered into the tonnage calculator prior to beginning the job. The actual bore of the cylinder, the length of the work piece, the material that is to be cut, and a safety factor should be entered into the calculator. The output of the calculator will indicate whether or not the job is compatible with the hydraulic press.
The output will indicate whether the system pressure of the press must be increased or the area of the tooling must be increased to distribute the force of the press. By performing these calculation with the hydraulic press tonnage calculator, the operator will avoid any overload event that may occur on the press. Overload events will prevent any repair and expense related to the press and the tooling on the press.
