A novel technique for assessing the frictional properties of fibers

A new test apparatus, in which compression force variation is measured by employing a full bridge strain gage load cell, has been developed for the assessment of the surface properties of textile fibers. The primary objective of the research was to establish a technique which could be routinely used to determine the frictional characteristics of textile fibers, from measurements carried out on fiber "bundles" rather than individual fibers. Hence, this should lead to information that is more meaningful in the prediction of processing performance and quality. The response time of the load cell was critical; therefore, customized load cell was manufactured by using strain gages. The prototype machine consists of a PC system with a data acquisition (DAQ) and a motion control card. At the beginning, the instrument had a considerable amount of unwanted noise that was superimposed with the signal coming from the load cell. Extensive noise reduction techniques were used to identify the source of the noise and resolve the problem. It was found that the sources were both electrical and mechanical. Mechanical noise was eliminated by using rubber-like materials as a damper in the system and it was necessary to separate the data acquisition and the motion control system in order to eliminate the electrical noise from the signal. Separating the motion control card and the DAQ card significantly increased the signal to noise ratio. Strain gages give a non-linear output, and it was necessary to establish calibration curves for each type of load cell.; In order to investigate the factors affecting the amount of compression force measured from the unit, a 2k factorial experiment was performed. The design was a full factorial with four factors at two levels and two replications at each level of the test. The factors were the test speed, fiber type, the amount of displacement, and the weight of fibers. Fiber types were raw cotton and cotton with no finish to serve as high and low levels of the factor. Statistical analysis showed that the speed of the instrument had no effect on the amount of compressive force obtained from the specimen in the testing intervals. The investigation showed that the measurement technique is a powerful sensitive aid to characterize between different fibers.; Additionally, 22 colors of dyed cotton fibers were chosen for testing. The QuickspinRTM system was used to provide a rapid assessment of the likely processing problems associated with different fibers. It was found that a higher load was necessary to compress the dark colored cotton samples. Examining the figures showed that the "bouncing effect" of the compression curve was related to change in fiber morphology due to color of the fibers. Light colored fibers usually had a linear compression while the dark colored ones showed nonlinear compression behavior. Polyester and Nylon 6 fibers were also tested. It was found that fiber finish and the shape of cross section of fiber were the driving components on the compressive force and the shape of the compression plot. The research work proved that it is possible to distinguish between different types of fibers by using the friction tester. The instrument also seems promising in predicting potential problems during different spinning processes. Such technique could be beneficial to technologist in predicting potential problems and avoid unnecessary costly trials.