Living in a materials worldThe next quarter century will undoubtedly see an acceleration of the existing trend towards the use of advanced composite materials in junction and control boxes, thinks Graham Fox of electrical engineers CEE Norm. Stronger and lighter than steel enclosures, plastics are cheaper to manufacture, cheaper to install, and in the case of the second- and third-generation materials now being used, at least equal in safety.
Plastics have been employed for enclosures for the last 50 years or so, being introduced in the 1960s. The first generation materials used then were mainly PVC, and nylon, which offered significant advantages over traditional metal boxes, but these materials are already being superseded by more advanced plastics and composites.
In the last decade or so in particular, we have seen the adoption of more sophisticated and higher-performance materials in the industrial enclosures market just as in other industries. Many developments have been led by the aerospace sector, notably in such high-profile projects as the Space Shuttle and the development of stealth aircraft. These materials filtered down to the civilian aerospace and automotive industries - the A380 superjumbo for example, the biggest airliner yet built and the world's first double-deck passenger aircraft, employs advanced composites for 20% of it's airframe including large sections of wing, fuselage, tail, and doors.
The materials used in these applications were once considered exotic and out of the reach of humble industrial application. But that is changing, as manufacturing production scales up and the benefits of the materials become more widely appreciated. The high-performance materials of the current era include carbon-fibre reinforced plastic, glass-fibre reinforced plastic, and quartz-fibre reinforced plastic.
It seems clear that the advantages of plastics - including capital cost savings, installation savings, ease of fitting, corrosion resistance, and double insulation - will continue to make them the materials of choice for enclosures of all kinds.
Safety is of course paramount, and it should be noted that in the specific case of fire performance - which might be thought by the inexpert observer to favour metals - modern composites can actually have better performance. Metal enclosures may expand, deform, and open under extreme heat, while plastic composites remain dimensionally stable. A current development at Hensel UK is a new material that produces zero smoke when caught in a fire. This of course is a potentially live-saving property in many applications, such as tunnels and mines, tall buildings, and offshore installations.
Looking further ahead, we are likely to see the development of third-generation plastics based on biological rather than fossil feedstocks. Anybody who has bought petrol recently will be aware that oil is a finite resource, and is no longer the cheap raw material it once was. Future developments will doubtless involve 'bioplastics' made from algae or vegetable matter. These are already becoming available, but are still in early development. Many of the bioplastics in production today are intended to biodegrade, but this is not necessarily an inherent property of the materials. Clearly the plastics used in industrial applications would have longevity as a prime requirement.
The enclosure of the year 2036, then, will be a lightweight, robust, and corrosion proof box made of a bioplastic from a renewable resource, offering colour fastness, electrical insulation, and fire resistance as well as the capacity to be drilled and sealed. It will, of course, also be fully recyclable.
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