Dow-United Technologies Composite Products (Dow-UT) has improved its advanced resin-transfer moulding (AdvRTM) process to enable production of more complex carbonfibre parts.

The improved process uses shaped unidirectional-fibre preforms to fill the gaps where two or more sections are moulded together.

When using conventional RTM, these gaps would fill with resin as it is injected into the mould. This excessive resin build-up reduces the joint's strength, says Dow-UT.

In the company's AdvRTM process, preshaped carbonfibre parts, called dry preforms, are assembled in a mould into which resin is then injected. In the improved process, gaps between sections are filled during dry assembly with triangular-section carbonfibre preforms.

These are then injected with resin during the moulding process and become as strong as the rest of the component, according to Dow-UT.

The improved AdvRTM process allows complex multi-part components to be moulded in a single operation, says the company. The technique is already being utilised to produce composite parts for commercial jet engines, as well as for military-aircraft wings.

Source: Flight International