KEVOS® MAKEOS · Hydraulics
Hydraulic Press Cycle Check (Regenerative Approach, Pressing Force, Return, Cycle Time, Motor Power)
For a hydraulic press with this cylinder and pump, how fast are the approach, pressing and return strokes, does it reach the pressing force, how long is a cycle, and is the motor big enough?
Cycle check of a single-cylinder hydraulic press: cylinder areas, approach speed and the pressure needed to overcome the approach resistance with a standard or regenerative approach circuit, pressing speed and the force at the relief pressure (as the hydraulic cylinder tool), return speed, the stroke times and total cycle time with dwell, and the motor power at the pressure needed for the pressing force and at the relief pressure (as the hydraulic power tool), against the force needed, the cycle time target and the installed motor.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Cylinder bore | mm | Bore of the press cylinder. |
| Rod diameter | mm | Diameter of the piston rod. |
| Pump flow | L/min | Pump delivery at working speed. |
| Relief valve setting | bar | Relief valve (maximum system) pressure. |
| Approach circuit | choice | Whether the approach stroke uses a regenerative connection or a standard one. |
| Stroke and load | ||
| Pressing force needed | kN | Force the press must reach on the work. |
| Resistance during the approach (negative if the ram weight helps) | kN | Force resisting the approach (guides, seals, stripper springs), less the ram weight on a down-acting press. |
| Approach stroke | mm | Length of the fast approach stroke. |
| Pressing stroke | mm | Length of the slow pressing stroke. |
| Dwell at pressure | s | Time held at pressure at the bottom of the stroke. |
| Targets | ||
| Overall pump efficiency | % | Overall efficiency of the pump (from its data sheet). |
| Installed motor power | kW | Rated power of the electric motor. |
| Cycle time target | s | Cycle time the press must achieve. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Cylinder bore
- What it is
- The inside diameter of the press cylinder, which sets the full piston area that gives the pressing force and the pressing speed.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 2000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 100 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger bore raises the pressing force but slows the pressing stroke.
- Get it right
- Use the nominal bore from the cylinder data sheet, not the tube outside diameter.
What this means: Rod diameter
- What it is
- The diameter of the piston rod; its area sets the force and speed of a regenerative approach, and the annulus left around it sets the return speed.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 2000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 70 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger rod slows a regenerative approach and speeds up the return.
- Get it right
- It must be smaller than the bore; check it against buckling separately for long strokes.
What this means: Pump flow
- What it is
- The oil flow the pump delivers to the press at working speed, which divided by the working area gives each stroke speed.
- Units and format
- Enter a number in L/min: litres per minute. The form accepts 0.000001 L/min to 100000 L/min. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 40 L/min as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- All stroke speeds and the motor power rise in proportion; cycle time falls.
- Get it right
- Use the delivered flow allowing for volumetric efficiency, not the theoretical displacement × speed.
What this means: Relief valve setting
- What it is
- The relief valve setting, the highest pressure the circuit can reach, which sets the largest pressing force and the power if full flow passes over the relief.
- Units and format
- Enter a number in bar: bar (1 bar = 100 kPa). The form accepts 0.000001 bar to 1000 bar. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 200 bar as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Pressing force at relief and relief power rise in proportion.
- Get it right
- Use the pressure at which the relief valve actually opens, below the cylinder and hose ratings.
What this means: Approach circuit
- What it is
- Whether the oil from the rod end is fed back into the full-bore side during the approach (regenerative), making it faster but weaker, or returned to tank (standard).
- Units and format
- Choose one of 2 options from the list: Regenerative (rod-end oil joins the pump flow); Standard (rod end to tank).
- Example
- The form opens with “Regenerative (rod-end oil joins the pump flow)” selected as a worked example. Choose the option that matches your case.
- Effect on the result
- Regenerative uses the rod area for the approach: higher speed, lower force, lower approach time.
- Get it right
- A regenerative approach needs a valve that switches to standard connection before the ram meets the work.
Stroke and load
What this means: Pressing force needed
- What it is
- The force the press must apply to the work at the bottom of the pressing stroke, which the full-bore area must reach at or below the relief setting.
- Units and format
- Enter a number in kN: kilonewtons (1 kN = 1000 N). The form accepts 0.000001 kN to 1000000 kN. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 120 kN as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Sets the pressure needed and the motor power at the pressing load; the speeds do not change.
- Get it right
- Include the force of any stripper springs or cushions the press works against as well as the forming force.
What this means: Resistance during the approach (negative if the…
- What it is
- The force opposing the ram during the fast approach, such as seal and guide friction and stripper springs, less the ram and tool weight if the press acts downwards.
- Units and format
- Enter a number in kN: kilonewtons (1 kN = 1000 N). The form accepts -100000 kN to 100000 kN. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 kN as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Raises the pressure the approach needs; a regenerative approach needs much more pressure for the same resistance.
- Get it right
- Enter a negative value when the ram weight more than overcomes friction on a down-acting press.
What this means: Approach stroke
- What it is
- The distance the ram travels quickly from its top position until it nears the work, before the circuit switches to the slow, full-force pressing stroke.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 250 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Approach and return times rise with it.
- Get it right
- Make it as long as possible so the slow pressing stroke covers only the working distance.
What this means: Pressing stroke
- What it is
- The distance the ram travels at full force and slow speed while doing the work, from contact with the work to the bottom of the stroke.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 30 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Pressing and return times rise with it.
- Get it right
- Include a small allowance before contact for the switch-over from approach to pressing.
What this means: Dwell at pressure
- What it is
- The time the ram is held at pressure at the bottom of the stroke before returning, added to the stroke times to give the cycle time.
- Units and format
- Enter a number in s: seconds. The form accepts 0 s to 3600 s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1 s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Adds directly to the cycle time.
- Get it right
- Include any time waiting for a pressure switch or timer; enter 0 for an immediate return.
Targets
What this means: Overall pump efficiency
- What it is
- The overall efficiency of the pump, combining volumetric and mechanical losses, which turns the hydraulic power into the shaft power the motor must supply.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 1% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 85% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Motor power needed rises as efficiency falls.
- Get it right
- Take it from the pump data sheet at the working pressure; gear pumps are usually less efficient than piston pumps.
What this means: Installed motor power
- What it is
- The rated power of the electric motor driving the pump, compared with the shaft power needed at the pressing load.
- Units and format
- Enter a number in kW: kilowatts. The form accepts 0.000001 kW to 10000 kW. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 15 kW as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Only moves the motor check; the power needed does not change.
- Get it right
- Use the nameplate rating; a motor can take short overloads but not continuous running over relief.
What this means: Cycle time target
- What it is
- The cycle time the press must achieve to meet the required production rate, compared with the calculated cycle time.
- Units and format
- Enter a number in s: seconds. The form accepts 0.000001 s to 100000 s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6 s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Only moves the cycle time check; the calculated cycle does not change.
- Get it right
- Take it from the required output: available seconds per shift divided by parts needed per shift.
Method and formulas
- Areas: bore A_b = π D² ÷ 4, rod A_r = π d² ÷ 4, annulus A_a = A_b − A_r.
- Approach: regenerative speed Q ÷ A_r and pressure F_app ÷ A_r; standard speed Q ÷ A_b and pressure F_app ÷ A_b. Pressing: speed Q ÷ A_b and force p A_b; return: speed Q ÷ A_a (as the hydraulic cylinder tool).
- Cycle time = approach + pressing + return (full stroke) times + dwell; motor power = pressure × Q ÷ (600 η) kW at the pressure the pressing force needs and at the relief setting (as the hydraulic power tool).
- Example: 157.08 kN available against 120 kN; a 4.4789 s cycle needing 11.983 kW at the pressing load.
Limitations
- Ideal speeds with no leakage, valve shift time or acceleration; pressure drops in the valves and lines are not counted.
- A regenerative approach gives only the rod-area force; the switch to full-bore pressing must happen before the work is reached.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a press design before ordering the power unit
- See how much a regenerative approach shortens the cycle
- Find why a press is slow or stalls
Who it is for
- Hydraulic engineers
- Machine designers
- Toolmakers and press-shop engineers
What you get
- Approach, pressing and return speeds
- Pressing force and approach pressure
- Cycle time
- Motor power at the pressing load and at relief
Interpreting the result
- A regenerative approach is fastest when the rod is large compared with the bore, but its force is small: keep approach resistance low.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 365–368. Topic reference; no source tables or recommended settings are reproduced.
- Esposito A., Fluid Power with Applications (Pearson): regenerative cylinder circuits.
Learn the Concepts Behind This Tool
These KEVOS® Library readings explain the method this tool uses, with worked examples.
Method explained here · KEVOS® original book
Hydraulic and servo presses
In Power Presses by the Numbers
What it covers: Sizing a 400 kN hydraulic press's cylinder, pressure, speed and power, its cycle time for MP-40 and AB-75, servo-driven presses, and the energy a compressed oil column releases at breakthrough.
KEVOS® tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.