A Quickstep Into Spaceage Materials

Advanced polymer composites are extremely strong and light - around 10 times the strength to weight ratio of most metals. These are highly desirable qualities, but until now have been out of reach of most manufacturers, according to CSIRO researcher, Dr Jonathan Hodgkin.

"Stealth fighter aircraft and very expensive racing cars are made out of these materials. But the problem with this technology has been that these materials are expensive and time consuming to manufacture, requiring high temperatures in a high pressure apparatus for up to 16 hrs for each part," Dr Hodgkin says.

"These disadvantages of time and cost meant that only the aerospace or racing car industries could afford the technology."

The new Australian process, called Quickstep, looks set to change that.

Dr Hodgkin, says that the Quickstep process is a fast fabrication method for making very high quality (to aerospace standard) composite products without using an autoclave.

Quickstep is one of the Australian technologies that will be on show at the Hannover Fair in Germany from April 23 - 28, 2001.

The technique takes advantage of the thermal conductivity of fluids such as water to reduce the production time from 24 hours to about 1hour for aerospace standard epoxy resins with even shorter production times for AAA grade automotive and marine composites. In addition the apparatus required is very low cost compared to conventional equipment.

The process was invented and patented by Neil Graham of Perth, Western Australia to meet a need to make aerospace parts in volume and quickly without the prohibitive costs associated with autoclave ovens and tooling.

"Quickstep uses a unique, fluid filled, balanced pressure, floating mould technique, combined with vibration through the fluids to produce advanced fibre and glass reinforced composite components," says Mr Graham.

"The process has superior performance to autoclave, vacuum and atmospheric curing methods in terms of strength, stiffness and appearance."

Quickstep achieves this superior performance on larger parts with faster cycle times, at far lower pressures of 1 to 4 psi compared to autoclaves which operate at 60 to 200 psi and at lower labour costs than alternative aerospace grade production systems.

Mr Graham says that the surrounding fluid system means that the mould and the part being fabricated are supported by fluid and are not subjected to high pressure.

"Consequently, the mould doesn't need to be of heavy construction. In addition, sandwich structures with honeycomb or foam cores are made feasible."

A number of different polymer-fibre systems have been tested by the CSIRO researchers, including epoxy/carbon fibre and vinyl ester/fibre glass. In each case, the resulting composites had very high fibre levels, often over 70 percent, with little porosity and were deemed to be of good aerospace quality.

"The process has a number of advantages over current systems for composite fabrication such as autoclave cure," says Dr Hodgkin.

"It is faster and cheaper and can use low cost moulds, even with large complex parts. It would be possible, for instance to produce a fuselage or boat hull in a single process," he says.

"We can control the temperature of the fluid, which means we have greater precision in the curing process."

CSIRO has undertaken trials on the Quickstep process since early 1998. They are now working with Quickstep Technologies to develop this revolutionary process. A high temperature oil based plant is due for completion in late April 2001 to supplement the water based pilot plant which has been demonstrating the process since 1994.

In addition to working with two aerospace companies, Quickstep Technologies and CSIRO will invite members of the automotive and marine industries to participate in the development of the process to meet their specific needs.

"Because we can fabricate high quality foam-core composite, the technology is ideally suited to the boating industry. And lightweight honeycomb components find many applications in the auto industry," Dr Hodgkin says.

Mr Graham says that the environment will also benefit from the technology.

"This process will reduce excessive energy in the manufacturing process, and because it will produce lighter vehicles, it will lead to fuel savings."