The methods to evaluate the pilling classes of clothes by the computer image analysis were investigated. The results obtained are as follows. 1. Threshold T_a in the distribution of pill sizes must be estimated to exclude noises in the distribution curve, when pilling feature values are calculated to evaluate the pilling class of a sample . The T_a can be estimated in the following three methods : (1) estimating the T_a interval from the distribution curve of pill sizes for the sample ; (2) estimating the T_a by comparison between the distribution curves of pill sizes for the sample and JIS judgment standard photographs of pilling ; (3) using the T_a of the group in Japanese Industrial Standard (JIS) photographs which is selected by comparison between the mean area of pills-T_a curves for the sample and JIS standard photographs.
2. Pilling class of a sample is evaluated from its total number or total area of pills. In some sample, however, the results evaluated from the above two methods do not coincide. Therefore, two dimensional expression of pilling feature values are proposed. In this expression, the feature values of a sample are represented by the point whose ordinate is the total area of pills and abscissa is the total number of pills. Pilling class of a sample is easily evaluated by plotting its feature values in the figuredivided by the lines which connect the points representing pilling feature values for the same class using JIS standard photographs.
3. Pilling classes evaluated by visual inspection in JIS are scattered, but the average of pilling class of each sample agrees with the result obtained by the two dimensional expression.

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Effects of the geometrical configuration and dimension of an abrasion tester on the frictional fatigue behavior of spun yarns were investigated experimentally. Spun yarns of 63 tex were made of polyester staples of 51 mm length and 2 denier, and were examined by the abrasion tester which was developed by the authors. The wear and breakage of yarns result from the cutting and /or pull out of fibers.
(1) In the region where the diameter D of the frictional pin is smaller than 2.5 mm, the yarn breakage depends on the fiber cutting. With the increase of D the frictional energy E_b consumed up to the yarn breakage increases, because it becomes harder for the pin to cut the fiber.
(2) In the region of D
≥2.5 mm, the yarn breakage is dominated by the pull out of fibers. The wear and tear of yarns is partially suppressed by the transmission of twist from the thicker part to the abraded thinner part. Therefore, the large tention W applied to the yarn results in a large abrasion resistance E_b.
(3) When the stroke S of the frictional pin is too small (S = 12 mm), the yarn breakage depends on the fiber cutting. which brings about remarkably large E_b for the pin with D = 2.5 mm.

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A lock stitch sewing machine for industrial use has been fitted with a quartz transducer and one or two specially designed attachments which analyze the motion of the needle thread to measure the thread dynamic tension of the needle side and the feed lenghth and the feed velocity of the thread at the outlet or the outlet and the inlet of the tension regulator during the sewing operation at about 200 to 2500 rpm.
The attachment consists of a rotary angular meter, a rotary encoder a V-pulley. The needle thread was wound around the pulley.
Two kinds of sewing experiments were carried out under constant force of 30 g to pull the bobbine thread through the shuttie tension spring.
The experimental results are summarized as follows :
1) Motion open angle of the needle thread, θ_s at the outlet of the thread tension regulator isalmost independent of the sewing speed. Values of the θ_s range about from 30° to 40°.
2) The extent of the motion angle of the thread θ_s-e expands with the increase of the sewing speed.
And, the time required for the motion of the thread becomes short.
3) The mean feed velocity of the thread in creases with the increase of the sowing speed.
4) From the above results, if the rotational speed of the arm shaft increases, the intermittent supply of needle thread at the inlet of the ten sion regulator will be transformed into the con tinuous supply.
5) In the case of high speed sewing, the needle

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