End-breakage is assumed to occur in the fiber bundle which forms a triangle zone between a front roller nip line and a twisting point.
On the this assumption a theoretical investigation into end-breakage encountered during spinning has been made together with such factors as tension, yarn irregularity, number of fibers and fiber strength.
The following equation for calculating absolute values of end-breakage rate during spinning has been derived:
where R is the end-breakage rate for a predetermined spun length; Q is the stationary end-breakage rate; τ is the average spun length during end-breakage; m is the number of fibers which are caught simultaneously between the front rollers and the twisting point; n is the cross sectional number of fibers; λn is the probability that fibers n are caught between the front rollers; T is the tension exerting on the triangle zone, k(T) is the probability density function of T;p=1-q, q is the probability that a fiber is caught simultaneously between the front rollers and the twisting point; and g(x) is the probability density function of X in which X=T-S-R where S is the strength of the fiber bundle in the triangle zone and R is a mutual resistance against slippage.
Since the values calculated by the equation lie substantially within the scope of the empirically known end-breakage, it has been proved that the equation can be of practical use.

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The most characteristic features of the open-end spinning compared to the ring spinning are in the drafting and twisting mechanism. In the present paper, some discussion will be made on the analysis of the drafting and twisting processes in MS-400 open-end spinning and their relation to the properties of its spun yarn.
The mechanical characteristics of MS-400 are;
(1) Roller drafting device
(2) Ejector for fiber separation
(3) Special eyelet, a yarn guide attached to the axis of the drum.
These mechanisms make MS-400 a suitable spinning machine for man-made fibers.
In the first part of this paper, the behaviour of fibers in the ejector separated into individuals from a fiber bundle by the air stream will be considered. The discussion will be extended on the degree of fiber separation and the state of fibers, such as straightness at the outlet of the ejector.
The second part deals with some mathematical analysis of the process of fiber collection in the drum and its self-doubling effect on the yarn irregularity. It is shown that the self-doubling effect is extremely useful for decreasing the yarn irregularity of short wave length and for improving the blend uniformity of fibers in the yarn.
In the third part, the effect of the eyelet equipped in the drum is considered. The eyelet is shown to have a great influence on the yarn strength and on the end down in spinning.
In the last part, a brief mention will be made on the spinning features obtained by the practical production in MS-400.

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