Huntsman Polyurethanes Automotive has developed a polyurethane (PU)
system called Fiberim that increases manufacturing speed and reduces
component weight and manufacturing scrap in the latest generation of
variable-length fibre injection (VFI) processes. Unlike traditional
structural reaction injection moulding (SRIM), which uses a glass mat or
pre-form that has to be manually placed in the mould prior to PU
injection, VFI injects the glass reinforcement as lengths (up to 10cm) of
glass rope or ‘rovings’ directly into the PU liquid stream.
The technique results in glass fibres being more accurately distributed
across the entire mould cross section and produces a finished product
with a lower weight and reduced wall thickness than an equivalent SRIM
part. The process is speeded by using a robotically controlled,
integrated cut, mix and spray head (illustrated), the new PU technology
allowing sufficient ‘cream’ time for the robot head to distribute the
polymer and glass mixture over the surface of the tool and then move
clear before mould closure. The Huntsman product also cures more quickly
to compensate for the extended pour cycle.