Hydraulic Press Calculator for Force and Pressure

To select a hydraulic press, you must calculate a relationship between pressure, cylinder bore size, and the resulting force. According to Pascal’s principle, the pressure applied to a fluids is equally transmitted throughout the fluid. The cylinder bore determines the piston’s surface area; the force of the hydraulic press is the product of pressure times an area of the cylinder bore.

However, because of the losses in force caused by seals, valves, and hoses, the actual force produced by a hydraulic press is often less then calculate. These losses is typically between 5 and 15 percent of the total power of the hydraulic press. The seals and valves of the hydraulic press creates these losses.

How to Choose a Hydraulic Press

Therefore, such loss must be accounted for when you calculate whether a hydraulic press will produce enough force for your tasks. When considering a purchase of a hydraulic press, you must consider both extension and retraction strokes. During the extension stroke, the hydraulic fluid push against the area of the cylinder bore.

During retraction, the fluid fill the annular space between the cylinder bore and the piston rod. The annular space is more smaller than the cylinder bore. Thus, the force output of a hydraulic press during retraction is less than extension force.

For example, a hydraulic press with a 4-inch bore and a 2-inch rod will exert more force during extension than during retraction. The retraction force is considered necessary for ejection of cast parts or resetting the platens of the press. The speed at which the hydraulic press perform its strokes depends on the flow rate of the pump of the press and the total volume of the cylinder of the press.

The volume of the cylinder is the amount of oil that is require to fill the cylinder of the press. The flow rate of the hydraulic pump is the volume of oil that the pump can provide per minute. The longer the stroke of the press, the larger an oil reservoir that is required.

Additionally, the longer the stroke of the press, the slower that the press will cycle unless the pump increases the flow rate accordingly. If the flow rate of the pump is not matched to the hydraulic press cylinder volumes, the cycle time for the press will increase. Additionally, if the flow rate of the oil is insufficient for the hydraulic press, the hydraulic press may experience oil starvation, which can damage the seals of the press and prevent it from functioning efficient.

Other factors to consider when operating a hydraulic press are the efficiency of the press and the temperature of the hydraulic fluid. A hydraulic press is most efficient when the fluid remain at a steady temperature and doesnt leak. If the hydraulic press is continuously operating, the fluid will overheat.

For example, if the temperature of the hydraulic fluid rise to 140 degrees Fahrenheit, the viscosity of the fluid will change, which can reduce the efficiency of the press by 10 percent. Thus, to prevent overheating of the hydraulic fluid, you can use synthetic fluids in the press or install cooling systems in the press to maintain an efficient operating temperature. Other factors to consider in the sizing of a hydraulic press are the safety and structural integrity of the press.

You must include a safety margin of 20 percent in the calculations of the required pressure of the hydraulic press to account for side loads that may act on the press or the springback of the materials being processed. You must also consider the deflection of the frame of the press. Frame deflection is the bending of the frame of the press due to heavy load.

If the frame of the press should deflect, the force of the press will decrease. Means of preventing frame deflection in large press machines include the use of thick plating material or a four post design for the frame of the press. Additionally, the piston rod of the press must be thick enough to prevent buckling of the rod.

Rod buckling can lead to the failure of the press. Finally, a variety of reference tables and calculators are available to assist in the sizing of a hydraulic press. Tables provides information about the force that hydraulic presses of specific sizes can produce at specific pressures.

This information allows the designer of a press to easily determine the size and strength that is require for a specific task. Many of these tables also include information that allows the designer to convert the pressure of the fluid from one unit to another, such as from psi to bar. Additionally, you can use calculators to calculate the area of the piston, the volume of the cylinder, and the energy that is required to perform the tasks of the press.

Thus, these tools ensure that the designer of a hydraulic press can find a moddern model that meet the requirements of the parts that the press will manufacture and the budget for purchasing the machine.