Staking is the process of connecting two components by creating an
interference fit between the two pieces. One workpiece has a hole in it while the other has a
boss that fits within the hole. The boss is very slightly undersized so that it forms a
slip fit. A staking punch is then used to expand the boss radially and to compress the boss axially so as to form an interference fit between the workpieces. This forms a permanent joint.
[Degarmo, pp. 415–416.]
Thermoplastic staking
Thermoplastic staking, also known as heat staking, is the same process except that it uses heat to deform the plastic boss, instead of
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 at or near room temperature. Such processes are contrasted with hot w ...
. A
plastic
Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...
stud protruding from one component fits into a hole in the second component. The stud is then deformed through the
softening of the plastic to form a head which mechanically locks the two components together. It is a versatile technique benefiting from being quick,
economical and consistent. Unlike
welding
Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, primarily by using high temperature to melting, melt the parts together and allow them to cool, causing Fusion welding, fusion. Co ...
techniques, staking has the capacity to join plastics to other materials (e.g.
metal
A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...
,
PCBs) in addition to joining like or dissimilar plastics, and it has the advantage over other mechanical joining methods in eliminating the need for consumables such as
rivets and
screw
A screw is an externally helical threaded fastener capable of being tightened or released by a twisting force (torque) to the screw head, head. The most common uses of screws are to hold objects together and there are many forms for a variety ...
s.
Technology
Thermoplastic staking can be performed with a wide variety of technologies, including:
* Thermal tooling
* Thermal punch (or hot punch)
* Hot air cold upset
* Ultrasonic staking
* Cold forming
* Infrared staking
* Impulse staking
References
Bibliography
*.
Further reading
*Tres, Paul A., "Designing Plastic Parts for Assembly", 6th ed., 2006, {{ISBN, 978-1-5699-0401-5
Joining
Metal forming