The term ‘composites’ covers a diverse range of complex and varied materials, processes and products, serving a large number of application sectors.
A wide range of technology levels therefore exist, from hand lay-up GRP to autoclaved cured aerospace materials, and each application is often associated with a particular material and process to give the required performance and cost.
This has led to an industry made up of many small companies, each with fairly unique skills and market orientations.
Thermoset composites still take the lion’s share of the market and these are used in all areas of application from traditional semi-industrial processes (short production runs) to open moulding techniques and automated methods such as filament winding and pultrusion.
However, thermoplastic composites are experiencing a growth rate approximately twice that of thermosets, especially in Europe, with the automotive industry acting as the major pull due to the twin drivers of recyclability and weight.
In aerospace, weight alone is no longer the primary goal and the use of composites in new components such as wings rests as much on their ability to make the components at a competitive cost.
Military aircraft are already using composites in primary airframe structures on aircraft such as the Joint Strike Fighter, whilst the civil sector is not far behind, developing major composite structures for aircraft including the Airbus A380 and Boeing Sonic Cruiser. Additionally, there is a trend towards the manufacture of all-composite small aircraft, either pressurised or unpressurised, for business travel.
One area, allied to construction, that is seeing massive growth and investment is wind energy, and the inherent growth in the wind energy market should see increasing use of composites for turbine blades, in particular.
Significant trends in technologies parallel the market trends, with evolving materials and process technologies used to meet the market demands or legislation. Most notable is the increased use of thermoplastics (high performance and commodity grades) compared to thermosetting (eg polyester and epoxy) systems. A similar trend is seen in the compounds being used.
There is forecast to be a dramatic increase in the number of companies using GMT (glass mat thermoplastic) materials as opposed to SMC (sheet moulding compound) and BMC/DMC (bulk/dough moulding compound). This reflects the emergence of recycling as an issue for the automotive industry, the major customer for these high-volume processes. Additionally, there is a further trend towards Long-Fibre Reinforced Thermoplastics (LFTs) due to their combination of cost, processability and recyclability.
This is not to say that there will be a decline in the use of thermosets, just that the use of thermoplastics is growing faster. Thermosetting materials will still dominate composites for a long time yet, due to low conversion costs, as well as performance characteristics such as fire and chemical resistance.
In the fibres markets, carbon fibre is forecast to exhibit the highest growth, especially in lower performance applications, and there is also an increased trend to natural fibres due to their perceived lower environmental impact. There will be a marked increase in the use of stitched fabrics, at the expense of traditional unidirectional and woven formats, primarily because stitched fabrics allow higher deposition rates of material, hence faster cycle times and lower costs.
In manufacturing, there is a clear trend in the reduction of hand lay-up and the uptake of higher-skill, more capital intensive processes such as resin infusion and resin transfer moulding (RTM). Other increases in processes such as pultrusion, injection moulding and filament winding reinforce the trend towards higher levels of sophistication, cleanliness and automation.
Whilst composites offer an exceptionally flexible design alternative to traditional materials, there are still some barriers that restrict the faster uptake of composites in new products: <BR>Environmental and regulatory issues: whilst the use of lightweight composite parts improves the environmental performance of vehicles, there are concerns over emissions in the workplace and recycling of composite components.<BR>Cost-effective manufacturing: because of the limited control over raw material prices and high labour costs, cost-effective manufacturing processes are seen as vital. <BR>Skills shortages: most companies have this issue high on their priority lists. <BR>Awareness and education: lack of awareness amongst potential clients is expected to have a continued impact on the accelerated development of new composite parts. <BR>Standards and design codes: the lack of standards for composites restricts their uptake, whist the pre-existence of some standards precludes the use of composites. <BR>
As none of these barriers are insurmountable, the main composites industry bodies are working together to coordinate future activities.
The future of the composites industry looks exceptionally bright, with new composites products being developed continually.
By working to address the few limitations associated with composites, it is expected that composite materials will play an ever more important role in the development of future products.
Gordon Bishop runs NetComposites, a business dedicated to developing and providing knowledge on composites <A HREF=’http://www.netcomposites.com’>NetComposites</A>