Palram PALGAR - Manual (Page 32)

PALSUN® PALGARD™
Glazing Guide
32
Figure 32. Hot Line Bending Device
for PALSUN Straight-line Bending.
b) Linear cold bending could be used for forming a frameless ridge in a two-way sloped skylight,
or similar project getting clean one piece glazing running both ways. (Fig. 9, Fig.31a,b.)
c) It should be noted that linear cold bending requires knowledge & expertise in processing plastics, while
cold curving is relatively simple and easier to perform with less experienced workers.
d) Detailed “Cold Curving” & “Linear Cold Bending” processing information is available at PALSUN
Fabrication chapter.
2) Thermoforming:
a) PALSUN sheets can be quite easily fabricated by thermal processing. There is a special PALSUN type
designated specifically for thermal processing, equipped with special heat resistant masking films, able
to withstand the temperatures required for polycarbonate processing. This sheet requires no special
preliminary treatment and can be fabricated with its protective masks on, which protects
the prepared sheet from damage during further handling & installation.
b) A regular PALSUN sheet requires, in most cases, peeling-off the masking on both sides prior to a drying
process in a special oven to get rid of the moisture content in the sheet. A thermoforming process
without pre-drying would lead to bubbles and internal irregularities in the sheet created by
the evaporation of the water content under the over 100 o C temperatures required by the process.
c) The simplest fabrication, requiring no pre-drying, is
“Linear Thermal Bending”. In this process the sheet is
heated from one or both sides (depending on sheet
thickness) by linear electric heating elements, until the
bending area reaches the proper temperature (110-
120
o C)and softens. Then the sheet is bent along the
desired line to the required angle and left to cool down.
It is preferable to perform such bending in a special
bending device, enabling a clean and accurate bending
in direction, measurement and bending angle. (Fig. 32
right)
do not place the sheet too close to the heating
elements, for fear of scorching and meltdown.
It is possible to perform a few sequential linear bends
on the same sheet to achieve special angles & shapes.
d) Another thermoforming method enables bending a flat PALSUN sheet into an arched form smaller in
radius than possibly allowed by “cold curving”.
The sheet is “baked” inside a suitable oven to the required temperature until it softens, then taken out
and placed, quickly, over a prepared mold where it “drapes” down on the round mold, with possible
assistance of careful hand pressure pushing both ends towards the mold, and held there for a few
seconds until it cools a little and retains its desired shape.
A variation of that method uses an oven large enough to contain both the necessary PALSUN sheet and
the suitable heat resistant round mold with wheels. The sheet is placed on top of said mold and pushed
into the oven, where it ”bakes” and eventually drapes down due to its own weight. After a fixed period,
arrived at by experience, it is taken out, given last finishing touches by hand and left to cool down.