Cold sizing
Encyclopedia
Cold sizing is a squeezing operation performed at temperature
s significantly below the melting point
to finish the surface of a workpiece to ensure better dimensional accuracy and surface finish.
The sizing operation is a squeezing operation that minimizes the thickness of the metal
. Sizing is performed in an open die
and only the surface where the die and workpiece touch will be sized. Many ferrous
metal casting
s are sized to sharpen corners and flatten holes around piercings. Sizing pressure is determined by area to be sized, the metal used, and the change in metal thickness from the operation. Sizing is usually performed on semi-finished parts or parts that require an accurate finish. Stop blocks are used to ensure close tolerances.
Cold sizing, like all other cold forming processes, has a hot process counterpart. In addition to semi-finished parts, cold forming may be used on metal stock, sheet, bar, and rod stock. Cold sizing can be performed on various metals, both ferrous and non-ferrous, and even materials like polymer
s and plastic
s. Sizing is related to other squeezing operations like swaging
, coining, hobbing
, staking and rivet
ing, thread
rolling, and extruding
.
Although the whole workpiece may be inserted into the die, the sizing operation can give dimensional accuracy to a portion of the part based on the contact with the die. Sizing is mostly used to give a forged
or cast part better dimensional accuracy. Mated surfaces between touching parts like gear
s are often sized. The sizing operation also provides a better surface hardness and finish to the workpiece. Also, the sized surface of the workpiece gets denser and stronger when the operation is performed. The dimensional tolerance of the operation is about 0.025 millimetre (0.000984251968503937 in). Primary pressing or a compacting die are typically used when sizing small batches of compact. To keep costs down, larger batches of compact usually have a specialized die made specifically for the operation.
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
s significantly below the melting point
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...
to finish the surface of a workpiece to ensure better dimensional accuracy and surface finish.
The sizing operation is a squeezing operation that minimizes the thickness of the metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
. Sizing is performed in an open die
Die (manufacturing)
A die is a specialized tool used in manufacturing industries to cut or shape material using a press. Like molds, dies are generally customized to the item they are used to create...
and only the surface where the die and workpiece touch will be sized. Many ferrous
Ferrous
Ferrous , in chemistry, indicates a divalent iron compound , as opposed to ferric, which indicates a trivalent iron compound ....
metal casting
Casting
In metalworking, casting involves pouring liquid metal into a mold, which contains a hollow cavity of the desired shape, and then allowing it to cool and solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process...
s are sized to sharpen corners and flatten holes around piercings. Sizing pressure is determined by area to be sized, the metal used, and the change in metal thickness from the operation. Sizing is usually performed on semi-finished parts or parts that require an accurate finish. Stop blocks are used to ensure close tolerances.
Cold sizing, like all other cold forming processes, has a hot process counterpart. In addition to semi-finished parts, cold forming may be used on metal stock, sheet, bar, and rod stock. Cold sizing can be performed on various metals, both ferrous and non-ferrous, and even materials like polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
s and plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
s. Sizing is related to other squeezing operations like swaging
Swage
Swaging is a forging process in which the dimensions of an item are altered using a die or dies, into which the item is forced. Swaging is usually a cold working process; however, it is sometimes done as a hot working process....
, coining, hobbing
Hobbing machine
Hobbing is a machining process for making gears, splines, and sprockets on a hobbing machine, which is a special type of milling machine. The teeth or splines are progressively cut into the workpiece by a series of cuts made by a cutting tool called a hob...
, staking and rivet
Rivet
A rivet is a permanent mechanical fastener. Before being installed a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the buck-tail. On installation the rivet is placed in a punched or pre-drilled hole, and the tail is upset, or bucked A rivet...
ing, thread
Screw thread
A screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a straight thread and the latter called a tapered thread...
rolling, and extruding
Extrusion
Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed or drawn through a die of the desired cross-section...
.
Although the whole workpiece may be inserted into the die, the sizing operation can give dimensional accuracy to a portion of the part based on the contact with the die. Sizing is mostly used to give a forged
Forging
Forging is a manufacturing process involving the shaping of metal using localized compressive forces. Forging is often classified according to the temperature at which it is performed: '"cold," "warm," or "hot" forging. Forged parts can range in weight from less than a kilogram to 580 metric tons...
or cast part better dimensional accuracy. Mated surfaces between touching parts like gear
Gear
A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....
s are often sized. The sizing operation also provides a better surface hardness and finish to the workpiece. Also, the sized surface of the workpiece gets denser and stronger when the operation is performed. The dimensional tolerance of the operation is about 0.025 millimetre (0.000984251968503937 in). Primary pressing or a compacting die are typically used when sizing small batches of compact. To keep costs down, larger batches of compact usually have a specialized die made specifically for the operation.