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Pressure
Forming
Lormac
Plastics has over 40 years of experience in pressure forming of
quality custom parts.
Pressure
Forming is a sophisticated version of the vacuum forming process
utilizing air pressure as a forming aid to increase the detail
on the mold side. The pressure applied (up to 100 pounds per square
inch) is approximately five times higher than with vacuum forming,
which makes it possible to obtain highly detailed features at
close tolerances.
Pressure forming is proving to be a valuable technique for the
computer, electronic, furniture, industrial, and medical industries.
It is enabling them to get parts into the market quickly that
have the look of injection molding, without the lead times or
tooling expense. Pressure forming can provide the structural integrity,
aesthetics and design flexibility usually found only in injection
molded parts.
Benefits of pressure forming:
- sharp
edges
- under
cuts and reverse drafts
- tight
corner radii
- multiple-textured
surfaces
- better
control of wall thickness for structural integrity
- embossed
lettering
- and
other fine surface detail
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The
Thermo Pressure Forming Process
Clamping
The clamp frame ensures the plastic sheet is held firmly in place
during the pressure forming process.
Heating
Radiant heaters are normally used to heat the sheet which has
been positioned over the aperture of the pressure forming machine.
For thicker sheet both surfaces may need to be heated and more
sophisticated machines allow this. Heaters move into position
both above and below the sheet.
Pressure Forming
The hot sheet is transferred to the forming station, the upper
mold (or pressure box) and lower mold are brought together and
compressed air is introduced through the pressure box pushing
the material against the mold.
Plug Assist
Where a deep draw is required a top "plug" may be used
to push material into the mold during the pressure forming process.
Cooling and Release
The material is allowed to cool. The cooling process may be shortened
with blown air or even a fine water spray. The molding may then
be released from the mold by introducing a small air pressure.
Finishing
After pressure forming the part, any mold finishing may be performed,
such as: trimming, cutting, drilling, polishing, painting, screening,
etc.
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