The feasibility of friction stir welding with metal-to-polymer joints is
not fully understood, mainly because
of differences between friction stir
welding for metals and friction stir
welding of plastics. The low thermal
conductivity of polymers, along with
their complex molecular structure,
requires changes in welding tools and
tool design. More studies still need to
be conducted to understand how the
welding method can be controlled.
Of the welding approaches thus far researched, ultrasonic metal-to-polymer
welding seems to be a most promising
method for hybrid structures when
joining metals to polymers. There is
uniform mixing between the metallic
and polymeric part, which promotes
intermolecular contact and mechanical interlocking in the weld zone. High
joint strength can be achieved with
relatively low energy input and very
short welding times. It has been successfully employed to join metal and
Friction spot joining presents similar results as ultrasonic metal welding. However, this joining method has
been successfully applied only to low-melting-point metals such as magnesium and aluminum and is not applicable to very thick metals.
Laser welding of metals to polymers can be used to achieve stable
metallic, chemical, and covalent
bonds between metal and polymer
hybrid components. However, bonding occurs in the molten-solid interphase between the plastic and metal;
the metal does not melt.
to be a most
Metal-to-polymer welding processes are promising, but
still in the developmental stages; more studies need to be
done to effectively understand their feasibility and durability.
Note: References are well-documented and numerous.
To view them in the original white paper and to read the in-
depth research, refer to “Techniques for joining dissimilar
materials: Metals and polymers” ( http://www.ipme.ru/e-
Images are courtesy of the authors except where noted.
Paul Kah, Lappeenranta University of Technology,
Lappeenranta, Finland, can be reached at firstname.lastname@example.org.