A 'direct forming' process for polyimides
Saint-Gobain Performance Plastics has developed a direct forming process
that is capable of reproducing complex features in components made from
its Meldin 7000 series of high-temperature polyimides. The process uses a
precision moulding method similar to powdered metallurgy, including high
pressure mould presses, automatic resin feeding systems and computer
controlled hydraulics.
Meldin 7000 provides a precise, 'as-moulded' finished product with
tolerances typically in the region of +/-0.025mm for inside and outside
diameters. This often reduces or actually eliminates the need for costly
secondary machining operations. Moulded polyimide products can be used in
applications that are continuously exposed to temperatures of up to
315°C, and will tolerate intermittent exposures to temperatures as high
as 482°C.
There are two grades available in the 7000 series: the unfilled 7001 and
the 15% graphite filled grade 7021. The 7001 grade is suitable for high
temperature structural applications and electrically insulating welding
components, while the 7021's self-lubricating properties make it a
suitable candidate for aerospace bearings and guide-ways, where low
weight and dimensional stability are important factors.