Press technology

Metal processing and forming machinery covers a variety of types of machines. Following are to brief description of respective types of machines.

Press technology terms explained

Technical press related terms explained

ACCURACY Defines the accuracy compared to a theoretical value.
ANISOTROPY A property of metal products indicating metal sheet resistance to thinning during deformation process
ANTI-VIBRATION PADS Antivibration elements, made of elastomer material. They are used to isolate the machines from the footholds and to avoid propagation of mechanical vibrations, These will be absorbed by the antivibration pads in the shortest span of time
ARCH PRESS A type of press similar to a straight-side press with an enlarged bed and bell-shaped frame. The arch press can accommodate larger sheets of metal.
ATTITUDE TO DEEP DRAWING Characteristic of a material to be plastically forged through deep drawing operations
BACK-GEARED PRESS This version of geared presses allows a production with higher tonnage at reduced nominal speeds, thanks to an intermediate wheel-pinion gear system between transmission and eccentric shaft 
BALL GUIDES Hydraulic-driven ball guides system installed on the working table to better handle very large dies
BENDING Mechanical operation to forge an object applying different forces on it 
BENDING The shaping of sheet metal by straining the metal around a straight axis. A bending operation compresses the interior side of the bend and stretches the exterior side. Flanging, hemming, and seaming are all bending operations.
BLANK HOLDER Pressure arm
BLANKING Auxiliary function of the safety light curtains. It allows the introduction of objects in the protected field of the light curtains, without stopping the press operations
BLANKING Blanks are produced from the shearing or cutting of outside contours or shapes out of sheet or strip stock. For larger production runs, blanking is often done in multiple dies, and is combined with other operations such as piercing and forming in combination and progressive dies. A shearing operation that creates a hole in sheet metal by separating an interior section. The removed piece of metal is the desired section.
BLOCK WINDOW Presses with Monitoring capability -a window that monitors if a certain force has been reached, but not exceeded within a pre-defined range of displacement
BOLSTER PLATE Additional plate to reduce the distance table-ram
BOLSTER PLATE A plate or block attached to the top of the press bed where the die is fastened. In some rare cases the die is fastened directly to the bed.
BOTTOM DEAD CENTRE (BDC) Point at which the mobile part of the die is nearest to the working table of the mechanical eccentric press
BRACKETS Device on rolls for rapid die tooling on the working table, especially in case of heavy dies
CALIBRATION Operation to set an instrument to improve its precision and accuracy
CANBUS Controller Area Network - CAN (also referred to as CANbus or CAN bus) is a network used in many every-day products consisting of multiple microcontrollers that need to communicate with each other
CAPACITY The specified amount of force that a press is capable of exerting near the bottom of its stroke in order to carry out a stamping operation.
CE COMPLIANT CE marking is a safety standard that has been established by the European regulatory authorities
C-FRAME PRESS Another term for the gap-frame press.
CLAMP FEEDER Strip feeding device that uses pneumatically and hydraulically-activated clamps
CLEAN ROOM Nickel plated presses which are suitable for some clean room applications
COIL Metal sheet coil
COIL CAMBER Strip curvature measured by the deflection of the strip axle in relation to the ideal line
COIL HOLDERS They contain the coil strip laterally to ensure proper unwinding 
COILS Coils of metal sheet
COINING A plastic squeezing operation. Not suggested in the case of eccentric mechanical presses
COINING A squeezing operation usually performed in a closed die in which the metal is forced to flow and fills the shape and profile of the die. There is a definite change in metal thickness.
COLD FORGING Cold metal stamping, or at room temperature 
COLD WORKING The shaping of metal at temperatures much lower than the metal's molten state, often at room temperature. Cold working adds certain properties to the metal, such as increased strength and improved surface finish.
COLUMN Structure to which a press head can be mounted. Two types- C-frame (maximum clearance for work piece) and H-frame (minimal deflection)
COMPLIANT PIN A press fit type electrical connection that eliminates soldering. Schmidt has extensive experience in assembly & quality control of compliant pin assemblies.
CONNECTING ROD ECCENTRIC SHAFT An eccentric device of a mechanical press. This device combined in its position with the eccentric shaft of the press allows the stroke change
CONTINUOUS FORCE The force that a Servo press can generate indefinitely
CONTROL BOARD Bimanual control
CONTROLTOOL Software that facilitates Process data management, HMI & PLC editing
CONVEYOR BELT System to convey scrap material or the pieces produced after stamping
CRANKSHAFT The device in some mechanical presses that connects the ram to the flywheel.
CRIMPING Operation in which two different contiguous parts, thanks to interference, are joined together
CRIMPING An operation in which the open end of a can or shell is forced tight over or around a mating part. This type of work is limited largely to assembly operations.
CROWN The upper portion of a press containing the drive mechanisms or cylinders that guide the reciprocating motion of the ram.
CURLING The forming of an edge, having a circular cross section along a sheet, or around the end of a shell or tube. This operation is sometimes called false wiring.
CYCLE TIME Time required to produce a punched and cut-to-size piece. It indicates the span of time from one stroke to the following one
CYLINDER The main drive of a hydraulic press that uses fluid to force the motion of a piston encased within the device.
DECOILER Device that carries the strip to the straightener/feeder, thanks to spindle rotation
DEEP DRAWING Operation through which the strip is plastically forged and takes the form of a box or a cylinder
DEEP DRAWING Forming of deep recessed parts from sheet material by means of a plastic flow of the material worked in presses and dies.
DEFLECTION The amount of deviation from a straight line or plane when a force is applied. Effective presses reduce the amount of deflection during operation.
DELTA STROKE After reaching target force, move predetermined distance
DESTACKER It supplies the line with the pieces that have not been worked, taking them from a pile of strips, in order to allow their continuous feeding 
DIE 1. A tool used on a press for any operation or series of operations, such as forming, drawing, piercing and cutting. The upper member (or members) are attached to the slide (or slides) of the press, with the lower member clamped or bolted to the bed or bolster, shaped so that the material placed between them is cut or formed when the press makes a stroke. 2. The female part of a complete die assembly as described in (1). 3. A tool for cutting external threads. - Tool element used on a press for different operations like deformation, deep drawing and shearing
DIE COUPLING Using a die coupling facilitates quick tool change and is ideal for tooling that needs to be guided extremely accurately by means of a die set.
DIE CUSHION An attachment or press accessory which gives additional motion or pressure required in many compound press operations. The pressure medium can be rubber, springs, air or liquid (usually oil). Air (pneumatic) cushions are the most commonly used. Uses include blank holding, drawing, maintaining uniform pressure on a die part, knock-out, and stripping. Typically mounted in order on the press bed, they can sometimes be mounted on the top of a press slide flange.
DIE CUSHION BLANK HOLDER Additional device of the mechanical press, installed under the working table with an extracting function (in case of pieces stuck on the bottom side of the die). It works also as die cushion for deep drawing applications 
DIE HEIGHT The closed height of a die during the working portion of the press or completed operation in the die. Die Height is measured from the top of the bolster plate to the bottom of the slide.
DIE SET The collective assembly of upper and lower die shoes, guide pins and bushings, and punch and die holders.
DIRECT ACTING A Press type that produces constant force through the entire stroke, unlike a toggle press
DUAL CHANNEL A type of redundancy. This can apply to electrical and pneumatic controls. Two channels (valves, relays, etc) must function properly in order for an action to take place.
DYNAMIC BENDING COMPENSATION A patented feature by Schmidt that allows achieving a high degree of position accuracy under varying forces
EC TYPE APPROVED Type-approval is a procedure by which the approval authority verifies that a vehicle or component type meets the relevant technical requirements.
ECCENTRIC Essentially a disk arranged to rotate around a center, not the center of dish but parallel to it. An eccentric should crank with a crankpin of such size that it contains or surrounds the shaft. The eccentric with its strap or connection is used in the eccentric press and for driving auxiliary attachments, such as lift outs and various types of feeds.
ECCENTRIC DRIVE A drive that uses an offset section to power the reciprocating motion of the ram.
ECCENTRIC SHAFT Main shaft of a mechanical press used to convert the rotatory motion, produced by an electric motor, into linear reciprocating motion (for stamping operations - through ram or slide)
ELECTRIC CONSOLE It integrates the electronic component of the press, PLC and safety modules. Separated from the press.
ELECTRIC ENGINE Main engine of the eccentric mechanical press. Used to activate the whole kinematic system
ELECTRICAL CONTROL BOX It integrates the electronic parts, PLC and security parts of the press
ELECTRONIC CAM Electronic system that, thanks to an encoder, creates some output signals, simulating more mechanical cams
EMBOSSING A process for producing raised or sunken designs in sheet metal by means of a male and female die.
ENCODER Electronic device used as transducer for angle position and axles rotation speed 
ENCODER WHEEL Wheel applied on the strip surface (after the feeder) and moved by the movement of the strip itself. Used to measure feeding lenghts
EXTRACTION FORCE Force needed to remove the piece from the die
EXTRACTOR BAR Extracting unit made of a metallic bar, integrated in the ram of the eccentric mechanical press. Installed to pull out the piece which gets stuck on the die upper part
EXTRUSION A process in which pressure is applied to a slug of metal causing the metal to flow either up around the punch (toothpaste tubes) or down in the direction of pressure (cartridge cases - Hooker process).
FEEDER Press feeding system to move coil strip
FEEDER WITH BUILT-IN STRAIGHTNER Before moving the strip to the mechanical eccentric press, this feeding device is able to straighten the strip, thanks to a multiple rolls system. The layout of this feeding line is meant to reduce the space compared with the usual layout with straightener apart. Suitable for stamping with average speeds and steps
FLANGING A bending operation that bends the edge of a part to add stiffness. Flanging most often creates a 90 degree bend in the metal.
FLASH Difect given by metal shearing
FLYWHEEL Wheel accumulating inertia (kinetic energy). The main device located in the crown of a mechanical press that is attached to the power source and regulates the reciprocating motion of the ram. It is able to prevent high or sudden speed variations, due to stamping operations
FLYWHEEL PRESS This version allows the use of higher speed with higher productivity, having no intermediate reduction between the drive shaft and the eccentric shaft
FORCE Total force generated by a press. Also see Pressure
FORCE PRE-SELECTOR An option for Hydro Pneumatic presses that allows presetting of maximum pressure / force independent from the main operating pressure.
FRAME The structure of a press that supports the ram above the base and guides the reciprocating motion of the ram.
GANTRY FRAME A closed frame (as opposed to a C-frame) that keeps deflection to a minimum
GAP-FRAME PRESS A type of press with a C-shaped frame suspending the crown over the bed and an open portion in the front. The open front of the gap-frame press offers easy access to the die set.
GIBS Guides or shoes that insure the proper sliding fit between two machine parts and which usually are adjustable for taking up excessive wear, e.g., press gibs that guide the press slide.
H-FRAME Same as Gantry frame
HORN PRESS A type of press with a cylindrical projection designed to position sheet metal parts for secondary operations.
HOT FORGING Overheated metal stamping 
HOT WORKING The shaping of metal at temperatures close to the metal's molten state. Metal that has been hot worked is often left with a rough, scaly exterior.
HYDRAULIC / HYDROPNEUMATIC CLUTCH Hydraulic clutch that allows a high number of engages per minute and it's not subject to wear
HYDRAULIC CLAMPINGS Hydraulic devices to allow easy die fixing on the eccentric mechanical press
HYDRAULIC CONTROL UNIT It provides the oil under pressure to the hydraulic circuit 
HYDRAULIC OPENING Feature of the decoiler, the spindle is hydraulically opened
HYDRAULIC POWER Power derived from the motion and pressure of a fluid, such as water or oil.
HYDRAULIC PRESS Press working thanks to a fluid pressure, usually hydraulic oil, to develop a force able to compress different materials, in order to compress and pack them
HYDRAULIC PRESS A press that is driven by hydraulic power. Most hydraulic presses are driven by one or more cylinders that use fluid pressure.
HYDRO PNEUMATIC A pneumatic press with an integral hydraulic section used as a pressure intensifier that enables generation of great force with normal compressed shop air.
INCHING A machine control process used to adjust and set dies and other tools by precisely controlling the working members of the press in short increments usually by rapidly engaging and disengaging the clutch or using electric or pneumatic push buttons.
INNER COIL DIAMETER Inner diameter of the metal sheet coil
INVERTER Electronic device that, thanks to frequency variation, allows the speed regulation of an eccentric mechanical press
IRONING A process in which the wall thickness of the shell is reduced without changing the O.D. of the shell (cartridge case work for example).
ISO International Standard Organization - engineered hardware designed to this standard is interchangeable, regardless of manufacturer
KN kilo Newton = 1,000 Newton = 225 lbs
L Metric unit of volume - Normal Liter ( 1 L = 0.0353 ft³)
LAMINATE Material obtained through a rolling process 
LANCING Slitting and forming a pocket shaped opening in sheet metal, without removing metal.
LINK MOTION A modified slide motion that produces either constant velocity or increased slow down through the working part of the press stroke.
LOAD CELLS Load detectors. They are used to simulate the press work under load. An interface system with a PC is able to detect the curves of force consumption 
LOADING CRADLE Decoiler device to allow easy loading of large coils
LOOP Situated between decoiler and straightener and between straightener and feeder. Used to balance the various speeds of the feeding machines to the mechanical eccentric press
LOOP CONTROL A system which controls the different speeds among the components of a feeding line
LOWER DIE SHOE The lower plate of a die set that contains the cavity into which the punch shears the sheet metal.
LUBRICATION With rolls or spray lubrication. It indicates a system which can make all stamping operations easier
MANUAL OPENING Feature of the decoiler, the spindle is manually opened by the operator through a manual system
MATERIAL OPTIMIZATION Actions taken to optimize the material, while reducing scrap material
MECHANICAL CAM Device fixed on a rotation axle that excites specific limit switches. This creates some output signals used in the machine.
MECHANICAL POWER Power derived from the use of solid tooling and machinery.
MECHANICAL PRESS A press that is driven by mechanical power. Most mechanical presses are driven by a flywheel, crank, and clutch.
METAL FORMING The plastic deformation of a metal in order to produce a useful shape. Sheet metal can be formed through operations that shear, stretch, bend, or compress the metal.
METAL SHEET Metallic material, available in coil or strips
MOTORIZED DECOILER This motor-driven device ensures that the material is fed to the straightener by the rotation of the spindle
MOTORIZED RAM Motorized device to allow easier ram regulation
NECKING Reducing the diameter of a portion of the length of a cylindrical shell or tube.
NOMINAL SPEED Speed at which the press can express its nominal power
NPN Designates output signal from a sensor. This sensor is sinking type and provides 0 Volt or negative voltage. Used with sourcing control input
OPC OPC is open connectivity via open standards. They fill a need in automation for exchange of data like printer drivers did for Windows
OPEN-BACK INCLINABLE PRESS A type of gap-frame press with a bed and frame that can be tilted backwards to encourage the removal of parts after they are separated from the strip.
OUTER COIL DIAMETER Outer diameter of the metal sheet coil
PDA Process Data Acquisition, collects & evaluates process data
PEAK FORCE The absolute, maximum force that a Servo press can generate for a very short amount of time.
PEDESTAL FOR CONTROL BOARD Mobile control board (bimanual control)
PIERCING A general term for cutting (shearing or punching) openings, such as holes and slots in sheet material, plate or parts.  Similar to blanking- the slug or piece produced by piercing is scrap, whereas the blank produced by blanking is the useful part.  In both cases the burr is opposite.
PILOTS In progressive dies, the precision of coil position in relation with the die, can be managed by pilots. They enter into holes, properly pre-sheared along the progressive die
PITMAN A connecting rod to convey motion and pressure from a revolving crank of eccentric to a sliding or swinging member, such as a slide or lever. A press connecting rod.
PNEUMATIC CLUTCH Pneumatic clutch combined with springs 
PNEUMATIC DIE CUSHION Pneumatic (air) attachment, consisting essentially of a cylinder piston, pressure plate and accessories generally used with a press for clamping, blank holding or ejecting.
PNP Designates output signal from a sensor. This sensor is sourcing type and provides 24 Volt or positive voltage. Used with sinking control input
POKA YOKE Japanese term which means 'mistake-proofing', often referred to as 'error-proofing', a means to easily identifies a flaw or error and prevent incorrect parts from being made or assembled. Typically, all sorts of sensors as part of the tooling or equipment are utilized to achieve this task.
POWER STROKE The distance over which a Hydro-Pneumatic Press can generate the rated force. The power stroke can occur anywhere within the total stroke of the press. Power stroke is not added to the total stroke of the press. A press model 62.100.6 has a total stroke of 100 mm and not 106 mm. 6 mm defines the power stroke capacity.
PRESS BASE For presses with inclination, it indicates the ground base on which the press frame is built
PRESS BED The stationary portion or "table" of the press to which the bolster is attached.
PRESS BRAKE The friction mechanism used to stop or control the motion of a press, feed or other mechanism.
PRESS CAPACITY Rated press capacity is the tonnage pressure the slide can safely exert at the bottom of the stroke.  Mechanical press capacity is typically based on  the bending capacity of the main shaft (crank, toggle, or eccentric shaft).
PRESS CLUTCH A coupling used to connect or disconnect a driving machine-member, such as a shaft or wheel, to or from a driven machine-member, such as another wheel or shaft. The engaging or disengaging can be done by a hand operated controlling device operated manually or automatically.
PRESS FORCE Force of the press (Ton)
PRESS WITH INCLINATION Press equipped with inclination to release easily the pieces produced (release due to gravity)
PRESS WITH TRANSFER In this version, the strip is carried through a transfer device that is able to move the strip step by step
PRESSURE A force based on a certain area, typically pounds per 1 square inch, or PSI. Pressure is not an indication of force generated, unless surface area is known.
PRESSURE ARM Made of a metallic mobile arm and of a wheel which pushes the strip to ease its introduction and start a new session, while working in complete safety. 
PRODUCTION RATE It indicates the number of pieces produced in a time unit- it is inversely proportional to the cycle time
PROGRAMMABLE SAFETY LIGHT CURTAINS Electronic safety devices to protect the working area of the press. The programmable functions are installed to improve the use of the press in case of productions in single stroke with manual loading and unloading. The cycle starts automatically after two or three accesses (you can select it from the control board). During the cycle, the possible new interruption of the light flow will block the press due to safety reasons.
PROGRESSIVE DIES A series of two or more dies arranged in line for performing two or more operations on a part, one operation (single or compound) performed in each die, at each station. Work in the form of a strip is usually fed to progressive dies automatically by a roll feed.
PUNCH Element of the die that, pushed by the eccentric mechanical press, carries out the shearing operation
PUNCH / STAMP The tool typically attached to the upper portion of the die set that shapes or penetrates the sheet metal.
RAM ADJUSTMENT Ram adjustment (by turning the screw between connecting rod and ram) which allows distance regulation table-ram to adapt the press to the die
RAM DRIFT LOCK Prevents the ram of a pneumatic press to drift downward in the case of air pressure loss
REAL TIME CLOSED LOOP FORCE CONTROL The Servo Press can accurately maintain the ram position based on force feedback instead of position feedback.
RECESS In a C-frame press, it indicates the distance between the machine axle and the frame (rear side of the table) 
REDRAWING The second operation following deep-drawing operations, in which cups are deepened and reduced in cross section.
REDUNDANT Serving as a duplicate for preventing failure of an entire system or unintended actions. Can apply to pneumatic as well as electrical controls.
REPEATABILITY This specification is independent from accuracy and indicates how well some criteria can be repeated.
ROD Mechanical linking element between the eccentric shaft and the ram
ROLL FEEDER Strip feeding device that uses two overlapping rolls, whose rotation activates the strip movement
ROTATING TABLE Used to convey, stroke after stroke, the different pieces to the die
SCRAP MATERIAL Waste material produced after stamping
SCRAP REMOVAL Scrap removal system after stamping operations
SEAMING A bending operation that joins the interlocking edges of two separate metal sheets together by folding them over one another.
SHEAR Instrument to cut off strips, scrap material and pieces produced
SHEAR FORCE A force that attempts to cause the internal structure of a material to slide against itself.
SHEAR STRENGTH The ability of a material to resist forces that attempt to cause the internal structure of the material to slide against itself.
SHEARING Operation of plastic deformation performed on metal sheet
SHUT HEIGHT The shut height of an upright press is the distance from the top of the bed to the bottom of the slide with stroke down and adjustment up. The shut height must always be defined either from the top of the bed or from the top of the bolster. The shut height of a horizontal or inverted press, or of a press with adjustable bed, can be defined in a similar manner. Generally the shut height is equal to the maximum die-height of the die that can be accommodated, taking the bolster into consideration.
SINGLE CHANNEL Relates to electrical & pneumatic controls. Single channel is non-redundant. Single channel does not require two valves or two electrical ciruits to operate simultaneously in order for an action to take place.
SINGLE IMPRESSION DIE Die with single impression to produce the requested piece
SLIDE / RAM The most common name for the main reciprocating member of a press, guided in the press frame and to which the punch or upper die is fastened. It is also referred to as the ram. The inner slide of a double action press is called the plunger- the outer slide of a double action press is called the blank holder slide, and the slide of a hydraulic press is often called the platen.
SLIDE ADJUSTMENT The distance a mechanical press slide can be moved from its maximum shut height to reduce  the die space height. The adjustment can be performed by hand or with a power mechanism.
SLOPE DETECT Used as a criteria for the point when a servo press ram is to stop pressing and return. Slope refers to ratio between traveled distance vs. increase of force.
SOUNDPROOFING BOOTH It completely closes the stamping line, reducing the noise level of the system. 
SPC Statistical Process Control
STAKING An operation in which two or more parts are assembled permanently by upsetting a small portion of metal over the mating part, causing the compression on the assembled parts.
STAMPING The process of forming sheet metal at room temperature with the use of dies and punches.
STEEL RULE DIE A cutting tool that uses a thin steel blade, used to cut thin material. The blade cuts against a urethane or steel pad
STRAIGHT-SIDE PRESS A type of press with supporting columns in each corner of the frame suspending the crown over the bed. The straight-side press offers improved rigidity and reduced deflection.
STROKE The distance marked by the farthest ends of reciprocating vertical movement of the press ram.
STROKE COMPLETION SENSOR Option for Direct Acting Pneumatic presses- ensures a stroke has been reached within an accuracy of 0.004"
STROKE RETURN LOCK Option for Manual presses- ensures the target stroke has been reached before releasing ram for return
STROKE TOLERANCE A type of monitoring criteria for Schmidt Presses with Monitoring capability
SUPPLY VOLTAGE Power supply voltage that needs to be supplied to the equipment
SWAGING Forming a metal by the rapid striking of a large number of successive blows. In the case of aircraft cable fittings, the fitting is rotated while the press blows are being struck.
TELE SERVICE Technical support in remote, performed by qualified staff with operations on the system
THREAD-CUTTING MACHINE This device can be integrated to the die to carry out tappings on simple holes or punched holes, during stamping operations
THROAT (GAP) The open space in a gap frame press back of the slide centerline. The depth of throat (gap) is the distance from the slide centerline back to the frame metal of the upright section.
TIE ROD Four long rods, with threads and nuts on both ends, which hold the frame members of a straight side press together.  These rods are stretched to place the frame members under compressive load.
T-NUT Nuts located on the plate and on the ram surface to fix the die
TOGGLE A linkage that provides a press with a mechanical advantage to achieve great output force over a short distance with little input force, thus allowing operation of a pneumatic toggle press with small cylinders.
TOLERANCE It indicates the interval in which a certain operation is performed, compared to the theorical design value
TOLERANCE WINDOW Used as monitoring criteria for a press with process monitoring capability. A window is defined by a lower & upper force limit over a pre-defined amount of displacement. The force curve must stay within the force limits of this defined displacement in order to pass the criteria.
TOOL Die or part of it
TOP DEAD CENTRE Point at which the mobile part of the die is farthest from the working table of the eccentric mechanical press
TRANSFER Device to carry the piece under the die
TRIMMING A secondary operation on drawn or formed parts, to remove excess metal on the flange or on axial length.
TURRET PRESS A type of press with an open frame and a turret containing multiple punches. Turret presses are mostly used to perform a variety of shearing operations, and they are typically numerically controlled.
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UPPER DIE SHOE The upper plate of a die set that secures the punch holder.
WORK INTEGRAL Area under the force/distance curve, i.e. the amount of work exerted during one press cycle.
WORKING STROKE Distance from the BDC (bottom dead centre). At this point the press works at its nominal speed
ZIG-ZAG FEEDER Feeder with lateral movement to allow productions with multiple impressions to reduce scrap materials