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Green composites technologies to revolutionize electrical industry
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composites technologies to revolutionize electrical industry
Green technologies being developed by Pera International will enable manufacturers of electrical products to meet critical EC legislation on electromagnetic (EMC) radiation. John Hill, of Melton Mowbray, UK based Pera, says that the legislation, which takes effect in four years time, states that electrical products must not interfere with other electricalgoods. They must therefore have in built shielding, which today means an additional metal coating. This is an expensive for example to process bring a telephone case up to EC standards could double its cost. Pera’s research team has spent seven years identifying three single-process moulding techniques using materials which can be recycled completely. These techniques produce shield components costing just a fraction more than unshielded products, says Hill. One area of study has investigated the incorporation of a copper coated nylon cloth into dough moulding compound (DMC) compression mouldings. It has been found that adequate wetting of the cloth can be achieved if moulding parameters are optimal. Subsequent EMC testing has shown that the resulting components provide excellent shielding characteristics. However,” the process was found to be labour intensive and operator sensitive. The cloth was also found to be somewhat delicate, so any development work in this area would also involve a metal mesh or gauze.
REINFORCED
PLASTICS
APRIL
1992
In order to increase the production rate and improve quality several modification may prove necessary, says Pera. Firstly, an automated preform manufacture process could be adopted. This would involve cutting of the mesh to size and subsequent pressing of the material to make a preform. The second improvement would incorporate robotic handling equipment to place the preform into the mould. The third area of development could combine thermoplastic injection moulding technology with the automation. This would permit the use of hot ‘liquid’ systems for the manufacture of composites rather than room temperature viscous DMC. The benefits of this approach would be improved cycle times, and complete wetting of the mesh with little or no rupture of the shielding material. The study has also assessed nickel coated graphite libre filled polymers and found them to be an excellent shielding system. The primary advantage gained from the use of this
filler material is that the final moulded components can be manufactured with shielding levels near to that of solid metal enclosures. However, the filler colours the surface of the mouldings with a grey tone. In an effort to redress this limitation, Pera believes that sandwich moulding could be adapted to produce shielded mouldings. The technique involves the simultaneous injection of differing materials so that a skin of one material is formed around a core of another. Pera says that the technology developed gives the functional and aesthetic benefits of injection moulded enclosures at much lower costs, and avoids using any environmentally unfriendly processes. The company has initiated a three-year collaborative project to refine the processes for industrial use. The aim is to involve manufacturers of electronic equipment and materials suppliers. John Hill, Peru Intmational, Melton Mowbray LE13 OPB, UK; tel: + 44 (0) 664-501501.
composites technologies to revolutionize electrical industry
Green technologies being developed by Pera International will enable manufacturers of electrical products to meet critical EC legislation on electromagnetic (EMC) radiation. John Hill, of Melton Mowbray, UK based Pera, says that the legislation, which takes effect in four years time, states that electrical products must not interfere with other electricalgoods. They must therefore have in built shielding, which today means an additional metal coating. This is an expensive for example to process bring a telephone case up to EC standards could double its cost. Pera’s research team has spent seven years identifying three single-process moulding techniques using materials which can be recycled completely. These techniques produce shield components costing just a fraction more than unshielded products, says Hill. One area of study has investigated the incorporation of a copper coated nylon cloth into dough moulding compound (DMC) compression mouldings. It has been found that adequate wetting of the cloth can be achieved if moulding parameters are optimal. Subsequent EMC testing has shown that the resulting components provide excellent shielding characteristics. However,” the process was found to be labour intensive and operator sensitive. The cloth was also found to be somewhat delicate, so any development work in this area would also involve a metal mesh or gauze.
REINFORCED
PLASTICS
APRIL
1992
In order to increase the production rate and improve quality several modification may prove necessary, says Pera. Firstly, an automated preform manufacture process could be adopted. This would involve cutting of the mesh to size and subsequent pressing of the material to make a preform. The second improvement would incorporate robotic handling equipment to place the preform into the mould. The third area of development could combine thermoplastic injection moulding technology with the automation. This would permit the use of hot ‘liquid’ systems for the manufacture of composites rather than room temperature viscous DMC. The benefits of this approach would be improved cycle times, and complete wetting of the mesh with little or no rupture of the shielding material. The study has also assessed nickel coated graphite libre filled polymers and found them to be an excellent shielding system. The primary advantage gained from the use of this
filler material is that the final moulded components can be manufactured with shielding levels near to that of solid metal enclosures. However, the filler colours the surface of the mouldings with a grey tone. In an effort to redress this limitation, Pera believes that sandwich moulding could be adapted to produce shielded mouldings. The technique involves the simultaneous injection of differing materials so that a skin of one material is formed around a core of another. Pera says that the technology developed gives the functional and aesthetic benefits of injection moulded enclosures at much lower costs, and avoids using any environmentally unfriendly processes. The company has initiated a three-year collaborative project to refine the processes for industrial use. The aim is to involve manufacturers of electronic equipment and materials suppliers. John Hill, Peru Intmational, Melton Mowbray LE13 OPB, UK; tel: + 44 (0) 664-501501.