|
Thermoforming is a an well established application, particularly
in thinner gauge since such products were driven by the needs of
the packaging sector. Most of the thermoforming of thin sheet rolls
have been highly automated. In the recent past, thermoforming of
heavy gauge sheets has been developing at a faster pace due to increasing
demand emanating from the automobile, building and construction
as well as the electronic industry. Thermoforming of heavy gauge
demands sheets to be heated through several heating stations to
a forming station. Secondary trimming steps such as sawing, routing,
shearing and drilling are usually essential to develop the finished
part of a desired quality. Simple thermoforming techniques are normally
not suitable since they cannot develop high pressures that are essential.
Pressure forming also can not develop more than 2 bars of pressures.
Another technique developed to press the hot sheet between two matched
moulds provides crisp texture of the mould without using high pressures.
The matched mould method and high pressure mechanical shaping eanbles
thermoforming of difficult polymers as well as composites to provide
the desired mechanical strength in the finished products. The greatest
growth is expected in HDPE or more specifically for UHMDPE since
these materials have high impact, chemical and weather resistance.
PP is also increasingly finding applications for thick thermoformed
products. Performance or engineering thermoplastics are also finding
applications where HDPE and PP cannot be used due to their lower
resistance to high source temperature.
|
