Interwet-LFI: new opportunities for glass-fiber reinforced parts

Interwet-LFI technology is an automatic and highly flexible process. It allows the use of a wide range of fillers with a fiber volume ratio up to 50%. For optimum tensile strength, fiber loading and reinforcement length can be adjusted during the spraying cycle. Deflectors near the spray head’s nozzles control fiber orientation, allowing uniform lay-down during production.

Interwet-LFI benefits

For parts that do not require precision surface aesthetics, the Interwet-LFI process alone can be used to produce structural and semi-structural GFR-PU parts and components. It is perfect for civil engineering projects. Manhole covers, frames, and chambers, for example, are all rendered significantly lighter than their steel counterparts, eliminating the need for heavy installation equipment, ultimately saving time, labor and costs.

The Interwet-LFI process can also be used for enhancing the structure of previously thermoformed, highly aesthetic polymer components. Spraying a GFR-PU layer onto the reverse side of external body panels for roofs, side and rear panels for buses, trucks, and agricultural vehicles, adds stiffness, strength, and durability.

Hybrid processes for high aesthetics

Interwet-LFI can be combined with in-mold barrier coating. The result is a multi-colored part with high surface aesthetics, excellent chemical and mechanical performance, that is bonded to the PU substrate — all in a single process.

A self-releasing primer, which eliminates the need for mold release agents, is sprayed onto the open mold, followed by a barrier coating. Then the GFR-PU formulation is injected and the mold closed. After curing, the part is de-molded, with a superior, paintable surface aesthetic.