Yarn Doubling – types, objectives, and application
Two-For-One or TFO for strengthening and reducing unevenness of ring yarns
Doubling reduces unevenness of single yarns and the strength of the doubled yarn is correspondingly better than the single yarns. In this article Ring Doubling, Two-For-One (TFO) twister, quality required by yarn to get best-doubled yarn are discussed.
Two-For-One (TFO) is a two-stage process where the yarns are doubled and then twisted. In TFO process two or more single yarns are twisted in order to enhance the properties of the end-products such as strengthening the yarns.
Generally, the wax is applied to yarns before the first twisting stage in order to reduce the friction on yarns.
Objectives of doubling
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- To increase the strength of the yarn
- To increase smoothness, evenness, lusture, uniformity, and compactness of yarn.
- To obtain the better deposition of a twist.
- Jeans sewing thread
- Type Cord
- Cable yarn
- Cutting yarn
Types of Doubling
The difference of ring doubling from the ring is:
- No drafting
- Creel in a system is different & creel contains yarn(No rove)
- Roller combination is different
Doubling Yarn is designated as follows:
Ends up with 40 Count 2/40 Ends up with 10 Count 3/10
Two For One twister (TFO)
Here yarn is transferred to a cone, then two ends yarns are combined (Doubled) and wound on a cone without twisting. Then the yarn is supplied to twister machine where the twist is applied in such a way that one revolution of rotating disc inserts two round of twist. The twisted yarn is then wound on a cone.
Qualities of Single yarn to get best-Doubled yarn
- The elongation of the yarn under lea strength tension should be uniform of the same count.
- The twist should be uniform throughout
- The breaking strength of yarn should not vary too much
- 4% tolerance on either side should be allowed.
The formula for Double Yarn Count
Single yarn of the same count
|Final count =||Single yarn count|
|No. of doubling|
- Resultant count of component thread
- Count: 1/N = 1/N1+1/N2 (N = Resultant counts, N1, N2= of same count yarn)
- TPI of doubled yarn = TPI of single yarn (60-70%)