Machine press
Machine tool that changes work-piece shape by pressure.
A machine press, also known as a forming press, is a machine tool that changes the shape of a work-piece by the application of pressure. The operator of a forming press is known as a press-tool setter, often shortened to tool-setter. Presses can be classified by mechanism (hydraulic, mechanical, pneumatic), function (forging, stamping, press brake, punch press), structure (knuckle-joint, screw, expeller), or controllability (conventional vs. servo-presses).
Historically, metal was shaped by hand using a hammer, with larger hammers eventually constructed to work thicker materials or more metal at once. A smith might employ a helper to swing the hammer while focusing on positioning the work-piece. Drop hammers and trip hammers used mechanisms to lift the hammer, which then fell by gravity. In the mid-19th century, manual and rotary-cam hammers were increasingly replaced by the steam hammer, first described in 1784 by James Watt but not built until 1840 by James Nasmyth. By the late 19th century, steam hammers had grown greatly in size; an enhancement in 1891 allowed a steam hammer to deliver a 125-ton blow. Most modern machine presses typically use a combination of electric motors and hydraulics to achieve necessary pressure.
Common press types include the shop press, often a simple rectangular frame with a bottle jack or hydraulic cylinder, used for general forming and pressing interference-fit parts like gears onto shafts. A press brake bends sheet metal into shapes such as brackets or electronic enclosures, with some having CNC controls for accuracy to a fraction of a millimeter and bending forces up to 3,000 tons. A punch press forms holes, while a stamping press shapes or cuts metal with a die. A screw press is also known as a fly press. Capping presses form caps from aluminum foil at high speeds. Servo-presses, driven by an AC servo motor, use a ball screw to convert torque to linear force, with pressure and position controlled via a load cell and encoder; their main advantage is low energy consumption, only 10–20% of other press machines. Press frames include the gap-frame (or C-frame), which allows access on three sides, and the straight-side press, which has vertical columns and eliminates angular deflection. The OBI (open back inclinable) pivots the frame for easier scrap or part discharge. Safety measures include bi-manual controls requiring both
- field
- Metalworking and manufacturing
- known_for
- Shaping metal and other materials through applied pressure
- types
- Hydraulic, mechanical, pneumatic; forging, stamping, press brake, punch press; knuckle-joint, screw, expeller; conventional, servo-press
Lore & Background
A forming press, commonly called a press, is a machine tool that reshapes a workpiece through applied pressure. Its appearance varies widely by type. A shop press typically has a simple rectangular frame, often made from C-channel or tubing, and uses a bottle jack or hydraulic cylinder to drive a ram. General-purpose shop presses apply between 1 and 30 tons of pressure. Lighter-duty versions are known as arbor presses. Other common press types include the press brake, which bends sheet metal into shapes like brackets or electronic enclosures; the punch press, which forms holes; the stamping press, which shapes or cuts metal with a die; and the screw press, also called a fly press. Presses are classified by their mechanism—hydraulic, mechanical, or pneumatic—and by their function, such as forging, stamping, or capping (forming caps from aluminum foil at high speed). Structurally, presses may be gap-frame (C-frame), which allows access on three sides and takes less floor space, or straight-side, which has vertical columns to eliminate angular deflection. An open back inclinable (OBI) press pivots its frame for easier part discharge. Controllability distinguishes conventional presses from servo-presses, which use an AC servo motor and ball screw to convert torque into linear force, consuming only 10–20% of the energy of other press machines. Safety features include bi-manual controls requiring both hands and light curtains that stop operation if an operator is in the die area.
Reader's Guide
Machine presses are fundamental to modern manufacturing, enabling the mass production of shaped metal parts ranging from automotive components to electronic enclosures. Their significance lies in their ability to apply controlled force to deform materials with precision and repeatability. The development of servo-presses, which use an AC servo motor and ball screw, has reduced energy consumption to only 10–20% of other press machines. Press brakes can bend sheet metal with accuracy to a fraction of a millimeter, while stamping presses shape or cut metal using dies. Safety measures such as bi-manual controls and light curtains are essential to prevent accidents. The evolution from manual hammers to steam hammers and then to electric and hydraulic systems reflects the ongoing drive for greater force, efficiency, and control in industrial forming processes.
Did You Know?
- A shop press is commonly used to press interference fit parts together, such as gears onto shafts or bearings into housings.
- A servo press can reduce energy consumption by 30–50% or more compared to conventional presses.
- A press brake can form parts with accuracy to a fraction of a millimeter and bending forces exceeding 2,000 tons, with some industrial models reaching 3,000 tons or more.
Gallery
Frequently Asked Questions
What is a machine press?
A machine press, sometimes called a forming press, is a machine tool that reshapes a work-piece by applying force through pressure. It sits at the heart of metalworking and manufacturing operations where material must be deformed rather than cut away.
What types of machine presses exist?
Presses are sorted by power source (hydraulic, mechanical, or pneumatic), by task (forging, stamping, press brake, or punch press), by structural frame (knuckle-joint, screw, or expeller), and by control style (conventional versus servo-driven).
Who operates a machine press?
The person responsible for setting up and running a forming press is known as a press-tool setter, a title that most shops shorten to simply 'tool-setter.'
How does a machine press differ from a cutting machine tool?
Instead of removing chips like a lathe or milling machine, a press deforms the work-piece by forcing it against dies or through a forming mechanism. The applied pressure reshapes the material into the target geometry without necessarily removing any stock.
What makes a servo-press different from a conventional press?
Conventional presses follow a fixed mechanical or hydraulic cycle, whereas servo-presses use electric servo motors to precisely govern force, speed, and position at every point in the stroke. This gives the operator much finer, programmable control over the forming action.
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