Strongwell brings unmatched capacity, technology, engineering, developmental
and overall general pultrusion firepower to its customers by producing
hundreds of thousands of feet of pultruded fiber reinforced polymer
(FRP) shapes every day!
The unique advantages possible with FRP have enabled pultruded profiles
to penetrate markets where other materials could not meet the design
or end use requirements efficiently.
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Pultrusion is a manufacturing process for producing continuous
lengths of reinforced polymer structural shapes with constant
cross-sections. Raw materials are a liquid resin mixture (containing
resin, fillers and specialized additives) and flexible textile
reinforcing fibers. The process involves pulling these raw
materials (rather than pushing, as is the case in extrusion)
through a heated steel forming die using a continuous pulling
device.
The reinforcement materials are in continuous forms such as
rolls of fiberglass mat and doffs of fiberglass roving. As
the reinforcements are saturated with the resin mixture ("wet-out")
in the resin bath and pulled through the die, the gelation,
or hardening, of the resin is initiated by the heat from the
die and a rigid, cured profile is formed that corresponds to
the shape of the die.
While pultrusion machine design varies with part geometry,
the basic pultrusion process concept is described in the schematic
shown below.
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See a video of the Pultrusion Process. For high speed connections (1.6 MB), choose the appropriate "High Speed Version" video. For lower connections (500kb), choose the appropriate "Low Speed Version.
The creels position the reinforcements for subsequent feeding into
the guide plate. The reinforcement must be located properly within
the composite and this is the function of the reinforcement guides.
The resin bath saturates (wets out) the reinforcement with a solution
containing the resin, fillers, pigment, and catalyst plus any other
additives required. The interior of the resin impregnator is carefully
designed to optimize the wet-out of the reinforcement.
On exiting the resin bath, the composite is in a flat sheet form.
The preformer is an array of tooling which squeezes away excess resin
as the product is moving forward and gently shapes the materials
prior to entering the forming and curing die. In the forming and
curing die, the thermosetting reaction is heat activated (energy
is primarily supplied electrically) and the composite is cured (hardened).
On exiting the die, it is necessary to cool the hot part before
it is gripped by the pull blocks (made of durable urethane foam)
to prevent cracking and/or deformation by the pull blocks. Strongwell
uses two distinct pulling systems, one that is a caterpillar counter-rotating
type and the other a hand-over-hand reciprocating type to pull the
cured profile to the saw for cutting to length.
In certain applications an RF (radio frequency wave generator) unit
is used to preheat the composite before entering the die. When in
use, the RF heater is positioned between the preformer and the die.
