Compared vnth corresponding speeds in other textile sectors, carding speeds in worsted processing have remained relatively static. Studies reported here reveal that carding speeds almost douhle those currently practised hy the industry may be readily used either to raise card productivity or to improve fibre length in the top and reduce comhing losses while maintaining production levels. Power consumption* wool regain, and selection of wool lubricant are discussed, as are preliminary results obtained by using carding speeds of up to three times conventional levels.
INTRODUCTIONIn converting raw wool to top, the major needs are to remove impurities, to individualize the fibres, and to reconstitute them in a parallel array as sliver in preparation for spinning.During this conversion, there is much fibre brefikage', particularly in carding, and many of the fibres are never completely fi"ee of entanglement. The result is that fibre is lost as waste in combing, there are unwanted impurities or neps in the final top, and top mean fibre length will be reduced. Top length is next only to micron value or diameter in determining top value so that the mechanisms that affect entanglement and fibre breakage in early-stage processing warrant careful study.The worsted card plays a vital role in this conversion process and is a major determinant of product quality and process economics. Together with combing, it is the most expensive process in topmaking. The productivity oi" the card is therefore of fundamental importance to the topmaker, provided that any increases in productivity are not at the expense of product qu.ality.The card productivity can be increased in three ways: (i) by increasing the feed rate; (ii) by increasing the card width; {iii)by increasing the card speed.Raising the production rate of the card by increasing the feed rate without increasing card speed increases the fibre-layer density on the surfaces of the cylinders in the card and results in reduced fibre length in the tops and an increase in combing waste or noil^-^. This deteriorating effect of increased production rate is mainly associated with increased loading on the swift of the card.The effect might be reduced if the efficiency of transferring fibres from the swift to the doffer could be increased, so that the density of fibres recycled round the swift past the doffer was reduced. This should enable the fibre-layer density to remain reasonably constant as the card production rate increases. Unfortunately, as recent studies by Eley et al.* have shown, this strategy is not effective, since the effect of increasing the density of fresh fibres being constantly fed to the swift is considerably greater in reducing fibre length and increasing noil than any benefits obtained by decreasing the number of fibres recycled past the swift/ doffer interface.
