Yarn Doubling – types, objectives, and application

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

• 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.

Doubling Applications

• Jeans sewing thread
• Type Cord
• Cable yarn
• Cutting yarn

Types of Doubling

1. Ring 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

2. 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

• 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%)