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What is twist S and twist Z for yarn?

Time : 2023-03-30 Hits : 8

Twist is an important factor in yarn quality. It determines how hard and strong a fiber is.

Almost every yarn that we use in knitting and crochet has twist (with the exception of flat man-made yarns). It is important to understand what twist is for yarn.

Most manufactured singles are spun with a Z twist, then plied together with an S twist to give a balanced ply yarn.

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Twist is the spiral turns given to fibers or yarn to hold them together and impart strength. It’s not a secret that twist is important to the way yarn works; it can make or break your knitting or crochet.

There are two main twist directions, left and right. A single strand of fibres in a yarn can have either an S or Z twist.

Most manufactured yarns have a Z twist if they’re single ply and an S twist if they’re plied. This is because of the mechanical design of a ring spinning system. Sometimes an S twist is used for special technical reasons, but most of the yarns we use as knitters and crocheters are Z twisted.

Increasing twist is an effective way of increasing the tensile strength of a yarn, and as this increases it becomes harder for the fibres to pull apart lengthways. This is why yarns with a low twist are more suitable for weaving and those with a higher twist are more suitable for knitting.

For dty textile yarns, twist is a key factor in predicting breaking tenacity and elongation at failure. The effect of twist on tensile properties is difficult to predict and current models.

To assess the impact of twist on yarn properties, a variety of dry textile yarns were subjected to different levels of twist in tension. Chord modulus, breaking tenacity and elongation to failure were measured for each sample.

It was found that both S and Z twist had a significant effect on the stiffness of dry textile yarns. A th model based on the helix angle performed poorly in predicting the effects of twist, while Rao and Farris’ stiffness matrix was slightly better.

As a result, a linear model that accounts for the entire rotation of the stiffness matrix was recommended as a more accurate approach to predicting the effects of twist on textile yarn properties. This model also did a better job of predicting the stiffness of dry textile yarns at low angles of twist, where existing models did not perform well.

In addition to affecting yarn properties, twist is also important in determining how the yarn behaves when it is worked. It can affect how the yarn splits during a stitch, and can influence how the fabric feels.

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