Shrink-fitting
Encyclopedia
Shrink-fitting is a technique in which pieces of a structure are heated or cooled, employing the phenomenon of thermal expansion
, to make a joint. For example, the thermal expansion of a piece of a metallic drainpipe allows a builder to fit the cooler piece to it. As the adjoined pieces reach the same temperature, the joint becomes strained and stronger.
Another example is fitting the iron strip around the edge of a cartwheel
. The strip will be heated and expands to the wheel's diameter
, and is fitted around it. After cooling, the iron rim contracts, binding tightly in place. A common method used in industry is the use of induction shrink fitting
which refers to the use of induction heating
technology to pre-heat metal components between 150˚C and 300˚C thereby causing them to expand and allow for the insertion or removal of another component. Other methods of shrink-fitting include compression shrink fitting which uses a cryogen such as liquid nitrogen to cool the insert, while heating the housing.
This technique falls under the broader category of interference fit
s.
Thermal expansion
Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.When a substance is heated, its particles begin moving more and thus usually maintain a greater average separation. Materials which contract with increasing temperature are rare; this effect is...
, to make a joint. For example, the thermal expansion of a piece of a metallic drainpipe allows a builder to fit the cooler piece to it. As the adjoined pieces reach the same temperature, the joint becomes strained and stronger.
Another example is fitting the iron strip around the edge of a cartwheel
Cartwheel
A cartwheel is a part of a cart. It may also mean:*Cartwheel , an acrobatic maneuver*Cartwheel Galaxy*Cart-wheel hat, worn by women*Slang term for a silver dollar coin -See also:...
. The strip will be heated and expands to the wheel's diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
, and is fitted around it. After cooling, the iron rim contracts, binding tightly in place. A common method used in industry is the use of induction shrink fitting
Induction shrink fitting
Induction shrink fitting refers to the use of induction heater technology to pre-heat metal components between and thereby causing them to expand and allow for the insertion or removal of another component. Typically the lower temperature range is used on metals such as aluminium and higher...
which refers to the use of induction heating
Induction heating
Induction heating is the process of heating an electrically conducting object by electromagnetic induction, where eddy currents are generated within the metal and resistance leads to Joule heating of the metal...
technology to pre-heat metal components between 150˚C and 300˚C thereby causing them to expand and allow for the insertion or removal of another component. Other methods of shrink-fitting include compression shrink fitting which uses a cryogen such as liquid nitrogen to cool the insert, while heating the housing.
This technique falls under the broader category of interference fit
Interference fit
An interference fit, also known as a press fit or friction fit, is a fastening between two parts which is achieved by friction after the parts are pushed together, rather than by any other means of fastening...
s.