A new torsional testing apparatus has been developed to measure the torsional property of single fibers and yarns with high accuracy and easy operation.
The torsional properties of spun, textured and filament yarns were measured under different yarn tension by this new apparatus, and the torsional property of single fibers. which were sampled from the yarns were also measured in order to investigate the interrelation between the properties of yarns and fibers.
The torque is measured by detecting the twisted angle of a thin steel wire connected with a specimen by means of a linear differential transformer.
When each of the fibers which compose a yarn is twisted without any interaction between fibers, the torsional rigidity of the yarn must be equal to the sum of the rigidity ofeach of the fibers. Here, α is defined as :
α=Rigidity of yarn/Sum of the rigidity of each single fiber
The α values for some of actual yarns were examined and observed that α depends on yarn tension and yarn structure, and represented by the experimental formula :
α=α₀+α₁W_t+α₂W_t²
where, α₀, α₁, α₂ are constants and W_t is (yarn tension) / (tex). The results show that although the values of α₀ for polyester and nylon multifilament yarns are almost unity, those of polyester spun yarns and textured yarns are value of 3 or more. On the other hand, α₀ of a worsted yarn, even though it is a spun yarn, is also unity.
Thus α is significantly related to fiber property as well as to yarn structure. Hysteresis in torsional property of these yarns are also examined and discussed in relation to the value of α.

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Slivers were separated into small fiber assemblies with several separating devices under various conditions, and the sizes of separated fiber assemblies were detected and recorded continuously. The weight distributions of separated fiber assemblies were analyzed using the analyzing method for particle size distribution in fracture process.
The cummulative weight distribution of fiber assemblies are similar to Rosin-Rammler distribution, and the probability density distributions to Weibull distribution p (x), where,
P (x) =β/αx^β-1e^-1/αxβ
The effects of separating devices, conditions and the sliver structure on these distributions can be expressed by simple parameters α and β.

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The possibility of practical development of an automatic fabric inspection system depends upon the following two points. One point is what kind of detector should be used, how to use the detector, and then, what degree of fabric defects can be detected. The another one is how to process the detecting signals from the fabric defects in order to recognize defects. Therefore, it is important to select the kind of detectors and to make the ability of the detector clear.
In this paper, the detectability of 23 kinds of defects on nylon filament plain fabrics was discussed using a photomultiplier tube and two kinds of light sourses, tungsten and He-Ne lasser.
The properties of reflected and transmitted light through the fabric defect differed according to the kinds of defect. The change of reflected light of laser was larger than that of tungsten. The detecting condition of 45-degree lighting and vertical reflecting were better than another conditions to detect fabric defects.
Fabric defects such as slippage, hole, crack, etc. are easily detected by transmitted light, and those such as tight pick, warp falling, double picks, etc. are easily detectable by vertical reflected light.

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Two kinds of ring spinning frame for worsted yarns have been experimentally developed to decrease the number of yarn breakages during spinning process. The first f rame was characterized by an extremely small spinning angle and snail wires were replaced by the“spinmasters”. The distance between“spinmaster”and the nip point of the front roller was almost equal to the average fiber length. The second frame was also characterized by the“spinmaster”and the distance stated above was a little shorter than the longest fiber. The number of yarn breakages was decreased to 1/48 by using the first frame and to 1/12 by using the second frame comparing with those of the existing frames.

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