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It is not only metals and plastics which can be bent but also wood, particularly when it is laminated. In this latter process, thin layers of wood are glued together and then placed in a former. Clearly preparing several layers of timber is time consuming so thicker pieces of timber can be bent after prior softening by being placed im a steam chamber.
Pressing Presswork
is the term usually applied to pressing metals, but wood glass and plastics
are also formed using presses. Metals are pressed at room temperature
although they may have to be annealed (heated and cooled slowly to reverse
the effects of work hardening) to ensure sufficient malleability. Glass
and thermoplastics, however, need to be heated before pressing.
This
technique is used to produce a number of household appliances such as
stainless steel kettles, enamelled toasters or large "white goods"
such as washing machines. For multi-curved shapes such as car body panels
the tooling costs are enormous on account of the complexity of the tooling
and the effort required to press such large panels. This means that it
is only economically viable for mass production. |