What’s the Difference Between a Mechanical and Hydraulic Press?

While serving the same purpose and having, mostly, the same general anatomy, there are some key differences between mechanical and hydraulic punch presses. The main structures that we discussed two weeks ago (Straight Side and C-Frame) can still be applied to both mechanical and hydraulic presses, however the difference lies with how the energy to cycle the ram is created.

Mechanical Power

A mechanical press generates its power, mechanically, meaning that a motor is connect in a variety of ways to a crankshaft that cycles the ram for one complete operation. The motor that generates the momentum is connected to a flywheel via belts, and in simple punch presses, is connected to the crankshaft and controlled by an attached clutch. In some bigger punch presses, the flywheel will attach to a pinion that attaches to an additional gear that rotates the crankshaft. In Straight Side presses, there will typically be two pinions and gears that run the singular crankshaft.

Here a mechanical press is continuously running through cycles. The main flywheel at the right feeds the clutch the power from the motor to cycle the crankshaft continuously.

Benefits of Mechanical Punch Presses

• Speed. The speed in which mechanical presses can be ran are higher than hydraulic presses. This allows for higher production and efficiency.
• Consistency of tonnage at bottom of the stroke. With a mechanical press, you’re maximum tonnage delivery happens in a smaller window as compared to a hydraulic press. However, this again helps attribute to the speed at which mechanical presses can be ran because you know the absolute limit of what your press will be hitting at the bottom of its stroke.

Hydraulic Power

The hydraulic punch press has no flywheel, and runs via pressure from hydraulic fluid.

Hydraulic punch presses run off of pressurized hydraulic fluid, just like any hydraulic machinery would. The ram of a hydraulic press is hooked up to a cylinder that receives hydraulic fluid via a motor that pumps the fluid.

Hydraulic presses tend to be used for slower, deep draw parts. The reason hydraulic presses are used for deep draw parts is because the hydraulic power allows for a more consistent source of pressure in a larger range of the stroke, as compared to a mechanical press. Hydraulic presses may be used for faster running parts as well, however, the ability to run deep draw parts is diminished the faster the press is ran. Ensuring that the proper amount of force is applied at the bottom of the stroke is crucial as well, to avoid over exertion of the material causing ripping and potential damage to the die and press.

Here is the ram of a hydraulic press. As you can see, there the tubing connecting directly to the ram that forces in hydraulic fluid to operate the punch press.

Benefits of Hydraulic Punch Presses

• Better forming and drawing capabilities. Hydraulic presses have a wider window within the stroke path of the stroke because the compressed air requires less motion to exert its full force compared to a rotating motor and flywheel.
• Better for smaller runs.
• Shut height variations don’t affect the force that can be applied.

Both mechanical and hydraulic presses have their strengths and weaknesses, but factoring in the different parts and functions you can create with a die, both styles of presses will always have a place to be used.