JEC COMPOSITES MAGAZINE - Issue #77 - December 2012 - 42

infusion

Pulsed Infusion: a new liquid moulding process

Pulsed Infusion is a new double-bag vacuum-assisted technology for the manufacture of composite materials. Its main innovation is the use of a suitably designed reusable pressure distributor that reduces material costs, labour time and waste.

Other important issues in the development of composite production processes are cost and waste. In fact, vacuum bagging in resin infusion can be time consuming and produces a high amount of waste due to the need for various ancillary materials – e.g. peel ply, distribution medium and vacuum bags – that have to be correctly positioned and cannot be reused after the processing cycle. To overcome the shortcomings of other infusion techniques, the Institute for Composite and Biomedical Materials of the Italian National Research Council and the Department of Materials and Production Engineering of the University of Naples now propose Pulsed Infusion, a new resin infusion method that can provide a cost advantage due to the use of a reusable flow distributor and reduced resin consumption and waste.

By
Vincenza Antonucci, Researcher Maria Rosaria Ricciardi, Short-term researcher Institute for Composite and Biomedical Materials, CNR

Technology concept
In conventional vacuum infusion processes (VIP, VARTM), the impregnation of the dry fibre reinforcement with a thermoset liquid resin occurs by vacuum application. The process basically involves three steps: lay-up of a fibre preform, vacuum application and fibre impregnation with a thermoset resin, and cure of the resin. The reinforcement, typically carbon or glass fabric, is placed on a one-sided rigid mould and a formable vacuum bag material replaces the common RTM matched metal tool. The resin is injected through one or more inlet gates, depending on part size and shape. Vacuum is applied through one or more vents in order to remove the air from the fibre preform and force the resin through the fibres for impregnation. A resin distribution medium is placed over the reinforcement to promote resin flow, allow complete wet-out of the preform

he resin infusion process has been long established in the manufacture of composite parts and tooling. In fact, the use of this technology has grown significantly since glass fibre boatbuilder/composite materials distributor Seemann Composites introduced SCRIMP (Seemann Composites Resin Infusion Moulding Process), 25 years ago. Many composite fabricators have recognised its numerous economical and environmental advantages over more conventional technologies such as autoclave, RTM and hand lay-up. Thus, the process is currently used in a broad range of industries, including the marine, wind energy, automotive and aerospace sectors. As its use has become more widespread, several manufacturing variants and ancillary products have been investigated and exploited primarily to improve laminate quality (higher fibre content, lower void content and improved surface finish). For example, double-bagging techniques and the Controlled Atmospheric Pressure Resin Infusion method (CAPRI, patented by Boeing Co.) were developed to manufacture composites with a higher fibre volume and lower void content than those produced by SCRIMP.

Fig. 1: The pressure distributor

42 jec composites magazine / No77 December 2012

JEC COMPOSITES MAGAZINE - Issue #77 - December 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #77 - December 2012