CompositesWorld
Issue link: https://cw.epubxp.com/i/830100
JUNE 2017 22 CompositesWorld WORK IN PROGRESS » In the early days of composites manufacturing, the materials for building fiber-reinforced plastic/composite parts were laid into molds by hand. Hand layup is still common in the industry, but automated processes — notably pultrusion, filament winding, automated tape layup (ATL) and others — have been developed along the way to replace or streamline manual operations. Pultrusion was one of the first automated processes. Patented in 1959 by W. Brandt Goldsworthy (1915-2003), pultrusion is an automated, computer-controlled process for manufacturing linear, constant-cross section, fiber-reinforced composite profile parts quickly, consistently and endlessly, and then reliably cutting them into pre-programmed lengths. Although early models could process only unidirectional reinforcements, later system designs have enabled the addition of multiaxial fabrics during processing. Typically a thermoset process, pultrusion also has been adapted for composite profiles with thermoplastic matrices. Historically, pultrusion has been limited in that the profiles it generates are oriented along a linear axis. In a word: straight. But nonlinear pultruded profiles were envisioned almost from Radius-Pultrusion process offers linear or curved profiles. Curved pultrusion? No longer an oxymoron FIG. 1 Curve-capable pultrusion process For most of its history, the pultrusion process has been limited to production of linear profiles. But Thomas Technik & Innovation's (Bremervörde, Germany) Radius-Pultrusion technology successfully turned out this pipe coil prototype for an oil company. Source | Thomas Technik the beginning. Goldsworthy and other composite pioneers soon asked, Why can't we make curved pultrusions? e earliest curved variant was probably Goldsworthy's Pulformer, patented and built in the early 1980s by his team as a contender for production of curved thermoset composite leaf springs for the automotive industry. e Pulformer combined step compression molding with pultrusion material infeed tech- nology to enable continuous, automated manufacture of curved parts and parts with non-uniform cross sections. In the end, the technology didn't fulfill the envisioned potential: Composite leaf springs are found on cars today, but they are molded, mostly by RTM. One automaker in the US and another in Japan bought Pulformers and did considerable research, but no Pulformed By Donna Dawson / Senior Writer Emeritus