Equipment/Tool Design and Development 137

air bending

A bending operation that uses a punch to force sheet metal into a die cavity, but without the sheet contacting the bottom of the die.

air gage

A non-contact pneumatic instrument that uses pressurized air to inspect parts.

backward extrusion

A process that forces material to flow backward around a punch as the punch presses through it. Backward extrusion is also called indirect extrusion.

bending

The process by which a material is formed into a desired angled shape. In sheet metal bending, the metal is strained around a neutral axis.

bilateral tolerance

A tolerancing method specifying an equal plus and minus deviation from a specified dimension.

blankholder

The tool in a drawing die that holds down the outer rim of the metal sheet as it is drawn into the die cavity.

blanking

A sheet metal shearing operation that removes an interior section of stock called a blank. The blank is the desired piece and often moves to other operations, such as punching or drawing.

bolster plate

A plate that is designed to hold the lower die shoe in place. The bolster plate is attached to the top surface of the press bed.

bottom bending

A bending operation that uses a punch to force sheet metal into a die cavity. During bottom bending, the sheet contacts all surfaces of the die cavity.

bottom-up nanomanufacturing

A nanomanufacturing process that builds larger material out of smaller materials.

bushing

A tube in a die assembly that fits over a matching guide post to align the upper and lower die during operation.

carbon nanotubes

A cylindrically shaped carbon molecule with enhanced physical and mechanical properties. Carbon nanotubes have been used to make stronger, lighter sports and automotive equipment and show potential for use in green energy and electronics.

CMM

Coordinate measuring machine. A sophisticated measuring instrument with a flat polished table and a suspended probe that measures parts in three-dimensional space.

combination cavity

In die casting, a die holding different impressions. Combination cavity die casting dies form parts with different shapes simultaneously.

combination die

A die designed to simultaneously perform more than one operation with each stroke of the press. For example, a combination die may blank and pierce in a single stroke.

coordinate measuring machine

CMM. A sophisticated measuring instrument with a flat polished table and a suspended probe that measures parts in three-dimensional space.

cutting die

A die assembly containing a cutting tool designed to shear or penetrate material. Cutting dies are usually mounted on presses and used in sheet metal operations such as shearing and trimming.

dial indicator

A measuring instrument with a contact point attached to a spindle and gears that move a pointer on the dial. Dial indicators have gradations that allow you to read different measurement values.

die

A complete production tool used to produce parts consistently to required specifications. Examples include a perforated block through which metal or plastic is drawn or extruded; the hardened steel forms for cutting or forming sheet metal; and the hollow molds into which metal or plastic is forced.

die button

An opening in a die that provides a space for the punch during operation. During sheet metal working, the slug or blank passes through this opening.

die casting

A thermal, high-pressure metal casting process that involves injecting molten metal into a mold at high velocity and pressure. In die casting, the mold is called a die.

die retainer

The area of the die containing the impressions or cavities that shape the metal. The die retainer also holds the die button.

die set

The collective assembly of upper and lower die shoes, guide posts, bushings, punch, retainers, and other die components. Die sets open and close during operation.

die shoe

A metal plate onto which the various die set components are mounted. Die sets typically contain an upper and lower die shoe.

direct extrusion

A continuous process that forces material to flow forward through a container and past one or more die openings. Direct extrusion is also called forward extrusion.

draft angle

A taper incorporated into a wall of a surface. Draft angles on die cavity walls allow for easier ejection of the part from the die cavity.

drawing

For sheet metal, a forming operation that transforms a flat blank into a cup-like shape. Sheet metal drawing involves a mating die set.

ejector pin

A device used to assist in ejecting parts from the die. Also called a knockout bar.

extrusion

A forming process that forces material to flow through a die opening or around a punch. Extrusion can form metal, plastics, and composites into a variety of shapes.

feature

A machine component designed to increase machine capability. Features may include enhancements such as safety controls.

flash

An overflow of excess material. During impression die forging, flash flows from the main die impression and into a gutter, and must be removed from the workpiece after the forging process.

footprint

A specification that indicates the amount of floor space a machine occupies.

forming die

A die assembly used to shape material without cutting. Forming dies are often mounted on presses and used in sheet metal operations such as bending and drawing.

gage

A device that determines whether or not a part feature is within a specified limit, or tolerance. Most gages do not provide an actual measurement value.

gage block

A hardened steel block that is manufactured with highly accurate dimensions. Gage blocks are available in a set of standardized lengths.

gage tolerance

An unwanted but acceptable deviation from a given dimension on a gage. Gage tolerance is typically ten percent of the work tolerance.

gagemakers' tolerance

A specification used to categorize the degree of accuracy of a gage. There are four primary gagemakers' tolerances, including XX, X, Y, and Z.

go/no go gage

A gage or gage set that includes a "go" and "no go" design. If the inspected part is within tolerance, it will pass the go test and fail the no go test.

guide post

A hardened rod used to guide and align the die shoes during operation. Guide posts fit into matching bushings.

heat treating

The controlled heating and cooling processes used to change the structure of a solid metal and alter its physical and mechanical properties.

impression die

In metal forging, a die containing a part-shaped cavity. During forging, the metal flows outside the cavity into a gutter to create flash.

inspection gage

A gage used to check parts after production. Class X gages are typically used as inspection gages.

knockout bar

A device used to assist in ejecting parts from the die. Also called an ejector pin.

limit dimensioning

A tolerancing method using an absolute maximum and minimum allowable dimension.

master gage

A gage used to check the accuracy of other gages. Class XX gages are typically used as master gages. Master gages are also called reference gages.

multiple cavity

In die casting, a die holding two or more of the same impression. Multiple cavity die casting dies form two or more parts of the same shape simultaneously.

nanomanufacturing

The process of precisely manufacturing substances atom by atom or molecule by molecule. Nanomanufacturing involves substances having at least one dimension in the nanoscale.

nanomaterial

A material with at least one dimension in the nanoscale, which is between one and 100 nanometers. Nanomaterials are commonly classified as either tubes, films, or particles.

nanometer

A measurement equaling one-billionth of a meter. Nanoscale ranges from one to 100 nanometers.

nanoscale

A range measuring between one and 100 nanometers. Nanotechnology involves materials of this size.

nanotechnology

The study and utilization of matter between one and 100 nanometers.

nominal value

A part's stated dimensions or ideal dimensions. Work tolerance is calculated based on the acceptable deviation from a part's nominal value.

notching

A sheet metal shearing operation that removes an area around the edge of the stock. Notched workpieces can then be bent into shapes, such as boxes.

open die forging

A forging process that compresses metal between two flat dies. Open die forging is also called hand forging or flat die forging.

optical comparator

A measuring instrument that projects an image of a part onto a screen to compare the shape, size, and location of its features. Also called an optical projector.

optical projector

A measuring instrument that projects an image of a part onto a screen to compare the shape, size, and location of its features. Also called an optical comparator.

piercing

Also called punching, a sheet metal shearing operation that creates a hole in metal stock. The metal removed to create the hole is scrap.

plug gage

A cylindrical gage used to inspect the size of a hole. Plug gages are available in standard diameters and are often two-sided, with a "go" side and a "no go" side.

precision die

In metal forging, a type of impression die that does not create flash. Precision forging dies are also called flashless forging dies.

press

A machine with a stationary base and an upper ram that moves along a vertical axis to shear, bend, or form sheet metal.

progressive die

A die containing a series of stations that perform one press operation after another in series. A progressive die gradually forms a part as it moves through the die, and the last operation separates the part.

punch

The tool typically attached to the upper portion of the die set that shapes or penetrates the sheet metal.

punching

Also called piercing, a sheet metal shearing operation that creates a hole in metal stock. The metal removed to create the hole is scrap.

reference gage

A gage used to check the accuracy of other gages. Class XX gages are typically used as master gages. Reference gages are also called master gages.

ring gage

A circular gage with a hole used to inspect the size of cylindrical parts or features. Ring gages are often in go/no go pairs.

screw pitch gage

A gage with teeth calibrated to check the thread pitch of a screw.

snap gage

A gage with a C-shaped frame used to test the external dimensions of parts.

specification

A description of the essential physical and technical properties of a machine or device. Specifications or "specs" describe a machine or device's functions and capabilities, such as its voltage and geometry.

stripper plate

The plate within a die assembly that strips the sheet metal stock from the punch as it retracts.

tolerance

An unwanted but acceptable deviation from a given dimension. Both workpieces and gages have specified tolerances.

tool steel

A specialized type of alloy steel that has excellent strength, toughness, and wear resistance. Tool steels are used in cutting tools, dies, and other industrial tooling.

top-down nanomanufacturing

A nanomanufacturing process that creates nanomaterials from larger substances by removing material.

unilateral tolerance

A tolerancing method using a deviation in only one direction, either plus or minus, from the specified dimension.

work tolerance

An unwanted but acceptable deviation from a given dimension on a part.

working gage

A gage used to check parts during the production cycle. Class Z gages are typically used as working gages.

X gage

On the gagemakers' tolerance chart, the gage classification with the second tightest tolerance level. X gages are less accurate than XX gages, and are often used for final inspection.

XX gage

On the gagemakers' tolerance chart, the gage classification with the closest tolerance. XX gages are usually used as master gages.

Y gage

On a gagemakers' tolerance chart, the gage classification with the third tightest tolerance level. Y gages are less accurate than X gages, and are often used as inspection or working gages.

Z gage

On a gagemakers' tolerance chart, the gage classification with the loosest, or least accurate, tolerance level. Z gages are less accurate than Y gages, and are generally only used as working gages.