Cold sizing is a squeezing operation performed at

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...

s significantly below the

melting point The melting point (or, rarely, liquefaction point) of a substance 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 depen ...

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 A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

. Sizing is performed in an open die and only the surface where the die and workpiece touch will be sized. Many

ferrous In chemistry, the adjective Ferrous indicates a compound that contains iron(II), meaning iron in its +2 oxidation state, possibly as the divalent cation Fe2+. It is opposed to " ferric" or iron(III), meaning iron in its +3 oxidation state, suc ...

metal

casting Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a ''casting'', which is ejected ...

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 In metallurgy, cold forming or cold working is any metalworking process in which metal is shaped below its recrystallization temperature, usually at the ambient temperature. Such processes are contrasted with hot working techniques like hot r ...

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 A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

s and

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...

s. Sizing is related to other squeezing operations like

swaging Swaging () is a forging process in which the dimensions of an item are altered using dies into which the item is forced. Swaging is usually a cold working process, but also may be hot worked. The term swage may apply to the process (verb) or ...

, coining,

hobbing Hobbing is a machining process for gear cutting, cutting splines, and cutting sprockets on a hobbing machine, which is a special type of milling machine. The teeth or splines of the gear are progressively cut into the material (a flat, cylind ...

, staking and

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 to the head is called the ''tail''. On installation, the rivet is placed in a punched ...

ing, thread rolling, and

extruding Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex ...

. 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 is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer (often a power hammer) or a die. Forging is often classified according to the temperature at which it ...

or cast part better dimensional accuracy. Mated surfaces between touching parts like

gear A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic ...

s are often sized. The sizing operation also provides a better surface

hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...

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 . 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.

Troubleshooting

This process is designed to achieve the desired dimensional tolerances of the forged parts. Elastic die deflection has been a problem in this operation so two solutions were developed. One solution is to make corrections in the die based on the elastic die deflection. It can be determined how much the workpiece distorted from the desired shape using a finite element analysis (FEA). This analysis is the basis the corrections are made on. The other solution is to apply a counter pressure by inserting an elastomer ring into the lower die in order to compensate the elastic die deflection.

References

* * * * * {{cite journal , last1 = Behrensa , first1 = B.A. , last2 = Doege , first2 = E. , year = 2004 , title = Cold Sizing of Cold- and Hot-Formed Gears , journal = CIRP Annals – Manufacturing Technology , volume = 53 , issue = 1, pages = 239–242 , doi=10.1016/s0007-8506(07)60688-x Metal forming