Linking Farming Systems to Fibre Quality and Textile Performance

Abstract

There is evidence the nep and short fibre content of Australian cotton is too high compared with other growths of similar quality. These characteristics are a result of the productive and efficient harvest and ginning practices utilized by the Australian industry but the problem is exacerbated by current lint cleaner design. In particular, the combination of lint cleaner elements, i. e. the feed rollers and feed bar, grid bars and the doffing brush around the lint cleaner saw, and the transfer ratios between these elements affect fibre quality. The broad aim of this project was to adapt and re-engineer the widely used fixed batt saw lint cleaner to reduce short fibre and nep content. The main adaption proposed at the start of this project was an auto-levelling system for the lint cleaner feed such that the weight of fibre transferred onto the saw would always be constant. Typically the unit is powered by a single 30kW motor, which regardless of the rate of fibre flow runs at fullspeed. Currently in lint cleaners there are no sensors to regulate fibre flow or draft settings. Excessive speed and large draft or combing ratios, ie. a high saw surface speed to feed roller speed, increase damage to the lint. Implementing an auto-levelling system requires sensors and variable seed devices to maintain a consistent flow of material. It has been shown in previous work that low combing ratios reduced short fibre content and improved fibre length and length uniformity. Introducing constancy to the batt weight requires a greater degree of control of this combing ratio effect. Thus, the initial focus in this project was to test the possibility of sensor control of mechanical elements, in particular the feed mechanism, in the standard fixed batt saw lint cleaner and CSIRO's Modified Lint Cleaner (MLC). As well as testing fibre and batt weight variation through the lint cleaner machine, work also concentrated on the application of additional mechanical elements, eg. a combed grid bar heel, designed to even the transfer of fibre onto the saw. Once achieved, the objective was then to link this mechanical control to moisture control systems being developed as part of New Ginning Technology for Australian Cotton: Part H (Moisture & Contamination) project. However, observations from flow and mass sensors applied to a commercial gin in the first year of the project, showed the delivery of fibre from the gin by the current system was too fast and too uneven to be controlled. Work on the project subsequently defaulted to proving and extending the veracity of the MLC to industry, with a view to commercialismg the MLC technology. Alternate fibre conveyor designs to give a more even feed and allow time for the batt to be levelled and humidified were drawn up towards the end of this project. These designs require greater intervention to the ginning system than was originally foreseen in this project. A new project around these designs was proposed to the CRDC in a FRP in January 2009.