Machine press

A forming press is a versatile machine tool used to change the shape of a workpiece. It achieves this by applying intense pressure to the material. This process is essential for manufacturing many common objects. The person responsible for setting up these machines is called a press-tool setter.

Presses are categorized in several ways. They can be classified by their mechanism, such as hydraulic, mechanical, or pneumatic. They are also grouped by their specific function or their physical structure. Some even differ by how much control a user has over them.

One common type is the shop press, which is used for general-purpose work. These machines often feature a simple rectangular frame made from tubing or C-channel. A hydraulic cylinder or a bottle jack inside the frame pushes a ram. This ram applies pressure directly to the workpiece.

Shop presses are frequently used in garages or machine shops. They are helpful for pressing interference fit parts together. This includes tasks like forcing gears onto shafts or bearings into housings. Depending on their construction, these presses can apply between 1 and 30 tons of pressure.

Other presses are designed for very specific industrial applications. A press brake is a specialized machine used to bend sheet metal. It can create parts like electronic enclosures, brackets, or the back-plate of a computer case.

Some advanced press brakes use CNC controls for extreme precision. These machines can form parts with accuracy to a fraction of a millimeter. The bending forces for these machines can reach as high as 3,000 tons. Other specialized machines include the punch press, which forms holes, and the stamping press, which uses a die to cut or shape metal.

Presses can also be categorized by their frame design. A straight-side press uses vertical columns on both sides to prevent angular deflection. In contrast, a C-frame, also called a gap-frame, provides easy access to the die area on three sides. This design is useful because it requires less floor space. There is also an OBI, or open-back inclinable press, which allows the frame to pivot. This pivoting helps workers discharge parts or scrap more easily.

Some machines even use timed air blasts or conveyors to move scrap away.

Modern technology has introduced the servo-press, which offers unique advantages. A servo-press, or electro-press, is driven by an AC servo motor. The motor produces torque, which a ball screw then converts into linear force. To maintain precision, the machine uses a load cell and an encoder to control position and pressure.

One major benefit is energy efficiency. A servo-press uses only 10% to 20% of the energy required by other types of presses. This makes them very effective for high-precision stamping tasks.

History shows how the methods of metal shaping have evolved significantly. Originally, metal was shaped by hand using a hammer. A smith might have an apprentice help swing the hammer while the smith positioned the work. Later, engineers developed drop hammers and trip hammers. These used gravity to fall a hammer onto the work. In 1840, James Nasmyth built the first steam hammer. This followed a description of the steam hammer by James Watt in 1784.

By 1891, the Bethlehem Iron Company created a steam hammer capable of a 125-ton blow.

Because these machines use such immense force, safety is a primary concern. Operators must follow strict protocols to prevent accidents. One common safety method is the use of bi-manual controls. These require the operator to use both hands on buttons to start the machine. This keeps the hands away from the dangerous die area. Another method involves light curtains. These devices can detect if an operator is within range of the die. If someone gets too close, the light curtain can stop the machine immediately.