Types of Hydraulic Presses

Hydraulic presses have been around since the late 1700s. They are also called Bramah presses in tribute to inventor Joseph Bramah, a multi-talented man who developed the flush toilet. In fact, studying the motion of fluids when installing toilets helped him create the first hydraulic press.

There is a wide range of hydraulic press types. All are press machines that work with either fluid or hydraulic pressure. Based on Pascal’s principle, a hydraulic press works because pressure builds up throughout its closed system, exerting equal force within all areas of the container.

4 Types of Power Presses

Hydraulic presses are categorized as power presses, an area that also includes mechanical, eccentric and pneumatic presses. Here is a look at the differences in the three:

• Mechanical presses generate power mechanically, using a motor that is connected to a crankshaft, which cycles the ram for each operation using flywheels and belts. The flywheel builds up pressure and then releases, transferring energy to the primary side in the process. The strokes of a mechanical press are called single-, double- or triple-action, based on the number of ram or slides it has. It can be adjusted within limitations.
• Eccentric presses are fairly new and have a more efficient drive mechanism. They have a linkage of the drive motor and the ram, which ensures that the operator is able to send signals to the motor to operate at a specific speed.
• Pneumatic presses use compressed air to produce dynamic movement. They can do most of the same functions as hydraulic presses. The big advantage of this type of press is its ability to reach up to 400 strokes a minute. They have a controlled flow rate, making it useful when ram velocity or flow rate is crucial. It also has fewer moving parts compared to mechanical and hydraulic presses.
• Hydraulic presses use some type of fluid to generate the pressure needed for dynamic movements.

What Makes Hydraulic Presses So Useful?

There are three good reasons that hydraulic presses are the most common in use:

• Their design makes them the most efficient.
• They are dependable, the workhorses of manufacturing.
• The level of force they reach can’t be duplicated with mechanical or pneumatic presses.

By far the most common material for constructing a hydraulic press is stainless steel, which makes them extremely durable.

Hydraulic presses are versatile heavy equipment because they come in both single and multi-station configurations. The single station has one set of tools inside the table, and multi-station units can handle several operations at the same time.

How Hydraulic Presses Work

The power in these presses is provided by hydraulic fluid, which produces the pressure that is generated. A press uses the standard parts for all types of hydraulic machinery, including pistons, hydraulic pipes, cylinders and a stationary die or anvil.

The pistons create a plunging or thrusting motion via liquid under pressure that exerts force. There are two primary cylinders, the small called the slave and the larger the master.

Oil or water is poured into the slave cylinder. As pressure builds is exerts force onto the piston in the larger cylinder. This larger piston then presses in the master cylinder. The action makes the punch connect with the die, which leads to deforming the metal into the shape that is desired.

Types of Hydraulic Applications

Hydraulic presses come in a wide range of types, suited to specific purposes. Here is an overview of several applications:

Platen presses
The C-frame press is an example of a platen press. All use a ram as well as a solid, and have a surface that is designed with stability in mind. They can be used for banking, drawing, straightening, punching, bending, forming and timing.

Vacuum and laminating presses
Credit cards are made with these presses, which encapsulate several layers of plastic. These presses can also apply film.

Stamping presses
These presses are commonly used in the auto and metal working field. They can cut and shape material with a process called deformation with die.

Transfer presses
Used most often in aerospace and the medical industry, these presses mold and stamp rubber.

Forging presses
These presses are used strictly on metal.

Two Types of Frames

C-frame hydraulic presses can be used manually or automatically. As a rule they take up less floor space than other hydraulic presses because of their C-shaped frame. These presses, made of steel, are sturdy and have very little deflection.

The H-frame hydraulic press is used for a variety of operations. As a laminating press, it uses two places, one for heating, the other for cooling. Using the two together speeds up the process of laminating. When it is used as a transfer press, flat material is fed in, often rubber, metal blanks or plastic. It is passed from die to die by a feed bar finger. Most are made for heavy loads, as high as 3,500 tons, but there are smaller presses also.

Hydraulic Press Types

Here is a look at the most popular types of hydraulic presses. Each has a distinctive application.

4-Post hydraulic press: these are used in precision tooling.

Arbor presses: these are used for bearings removal, assembly, seating stamping and repair of production jobs.

Assembly presses: these can generate enormous pressure to assemble and secure parts together.

C-frame presses: these presses are streamlined and sturdy, using a small amount of space. As a rule they have a single application.

Compression molding presses: these use two separate plates pushed together to compress material into the required mold.

Forklift tire press: these are used to remove solid tires off forklifts.

Gantry straightening press: this model straightens steel and other materials.

Forging presses: this is a metal forming machine that is powered by hydraulics, forcing metal to take on a specific shape using a particular mold.

H-frame presses: these are also called four-column presses, getting their name from the H-shape frame.

Hydraulic presses: these are industrial machines that use fluid to generate pressure, which lets them form and shape objects.

Laboratory presses: these are smaller size presses that have just one application. They are usually found in labs and testing facilities.

Laminating presses: these are used for impressing polymers onto other materials like metal, lumber or paper.

LIM presses: this stands for Liquid Injection Molding. It is used for plastics, produced through an injection process.

Mechanical presses: these are generally used for punching, shearing or assembly on specific types of materials, using dies or tools attached to rams or slides.

Platen presses: these are industrial hydraulic presses, using two large surfaces for condensing, forming or molding products.

Power presses: this is a type of hydraulic press that uses dies and tools for punching, forming or shearing.

Pneumatic presses: these use compressed airflow to generate energy, which is used to facilitate and control movement. Types of applications include bending, forming, shearing and punching.

Press brakes: either mechanical, hydraulic or manual presses, they can cold-work metal into different shapes.

Stamping press: these are machines that use stamping dies.

Straightening presses: these apply pressure to metal in order to straighten it.

Tableting presses: these are used to shape powdered materials into compacts or tablets.

Transfer presses: these are hydraulic presses that automatically move products from one process to the next.

Vacuum presses: these are industrial systems powered by hydraulics. They create air pressure for laminating operations.