A. Barella

26—A NEW HAIRINESS METER FOR YARNS

The fundamental principles on which a new electronic digital hairiness meter is based are described; an example is included to show its application to the study of the hairiness of a cotton yarn.

34—AN APPLICATION OF MINI-COMPUTERS TO THE OPTIMIZATION OF THE OPEN-END-SPINNING PROCESS. PART I: CONSIDERATION OF THE CASE OF TWO VARIABLES

The application of the technique of the central compound rotatable designs of Box and Hunter to the optimization of an open-end-spinning process is studied, and the advantages of using a minicomputer for such an analysis are discussed. The influence of the rotor diameter, rotor speed, and yarn twist on the characteristics of open-end-spun cotton yarns is studied. In each case, the optimum conditions within the industrially acceptable limits of the process are established.

51—RECENT DEVELOPMENTS IN YARN-HAIRINESS STUDIES

This paper is a further contribution to the series, begun in 1966 and continued in 1970, surveying the literature on yarn hairiness. The review of the literature is brought up to date at the time of writing.

51—AN APPLICATION OF MINI-COMPUTERS TO THE OPTIMIZATION OF THE OPEN-END-SPINNING PROCESS. PART III: THE EFFECT OF THE ROTOR DIAMETER ON THE PROPERTIES OF OPEN-END-SPUN YARNS

This third part of the series of papers dealing with the optimization of the open-end-spinning process clearly justifies some of the results obtained in the course of experiments reported in the first and second parts relating to the influence of the rotor diameter on the unevenness, tenacity, and breaking elongation of open-end-spun yarns.

46—NEW FEATURES OF YARN-HAIRINESS STUDIES

This paper is the fifth contribution to the series begun twelve years ago in which the literature on yarn hairiness is surveyed. The review of the literature is brought up to date at the time of writing, and an outline of a new electronic hairiness meter at present being developed closes the report.

41—AN APPLICATION OF MINI-COMPUTERS TO THE OPTIMIZATION OF THE OPEN-END-SPINNING PROCESS PART VIII: THE INFLUENCE OF THE INPUT-SILVER LINEAR DENSITY AND OF THE PARTIAL DRAFTS BETWEEN THE FEED AND THE ROTOR ON THE PROPERTIES OF COTTON YARNS: CONDITIONS AND RESULTS

The optimum conditions for the rotor-spinning of a given type of cotton, with the entry speed, total draft, and speed of production kept constant and the linear density of the input silver (and of the yarn produced) and the partial drafts between the feed and the rotor (feed–opening roller and opening roller–rotor) varied are established for yams of 26–40 tex.

18—AN APPLICATION OF MINI-COMPUTERS TO THE OPTIMIZATION OF THE OPEN-END-SPINNING PROCESS PART IV: THE INFLUENCE OF WINDING TENSION ON YARN PROPERTIES

The winding tension and package mass can affect the characteristics of rotor-spun yarns. The properties most affected are the elongation at break and yarn imperfections, particularly thick places, so that the yarn irregularity is also affected. Increases in winding tension above a given value reduce the yarn quality quite independently of the package mass. When the winding tension is low, however, this mass exerts some influence, the yarn quality deteriorating as the package mass increases.

39—YARN-HAIRINESS STUDIES TO-DAY

This paper is a further contribution to the series begun in 1966 and continued in 1970 and 1973, surveying the literature on yarn hairiness. The review of the literature is brought up to date at the time of writing.

19—AN APPLICATION OF MINI-COMPUTERS TO THE OPTIMIZATION OF THE OPEN-END-SPINNING PROCESS PART XI: THE OPTIMIZATION OF THE OPENING-ROLLER SPEED AND TWIST FOR PROCESSING CONDITIONS REMOTE FROM THE OPTIMUM DURING THE ROTOR-SPINNING OF COTTON YARNS

The optimum values for both the opening-roller speed and the yarn twist, in operating with near-extreme values of both the total draft and the rotor speed, are studied. These values of draft and speed are, nevertheless, not uncommon in industry. For a total draft of 173 and a rotor speed of 45 000 r/min, and with a Sussen Rotorbox machine, it was found that the optimum values of yarn twist and opening-roller speed did not coincide with each other when either the yarn regularity or tenacity was considered as the most important parameter, a phenomenon that had, in fact, been observed earlier when all the operating parameters were optimized. In this instance, the best quality indices are obtained for opening-roller speeds above 6000 r/min and twist multipliers, a, of about 160 for a 23.57-tex yarn (N e = 25).

18—AN APPLICATION OF MINI-COMPUTERS TO THE OPTIMIZATION OF THE OPEN-END-SPINNING PROCESS PART X: THE INFLUENCE OF TWIST AND TOTAL DRAFT ON THE PROPERTIES OF OPEN-END-SPUN POLYESTER-FIBRE YARNS

A study of the effects of the twist and the total draft on the properties of polyester-fibre rotor-spun yarns is reported. For a given fibre quality and for twist factors (a) between 94 and 148 and total drafts ranging from 85 to 165 (corresponding to a range of from 39 to 20 tex), it is found that the influence of the total draft on the yarn regularity is evident only from a certain twist level onwards; the same occurs in relation to the effect of the twist on the tenacity, which manifests itself only from a certain total draft onwards. For high twists, the yarn irregularity increases with the total draft, and for fine yarns the tenacity increases when the twist decreases, which indicates that in many practical instances, operation is in a hypercritical zone of twist. Elongation at break is influenced less by the variables in question, and the quality index presents an optimum region that goes from coarser and more highly twisted yarns to finer, lower-twist yarns.