unilay stranding
unilay stranded copper wire
TYPES OF STRAND CONSTRUCTION
Unilay concentric stranding consists of a central wire surrounded by one or more layers with lay direction same for successive layers, and with the length of the lay is also same for each successive layer. Normal direction of lay of the outer layer is left-hand.
Unidirectional concentric
Unilay concentric stranding consists of a central wire surrounded by one or more layers with lay direction same for successive layers, and with the length of the lay is different for each successive layer. Normal direction of lay of the outer layer is left-hand.
Equilay concentric (reversed lay stranding or SZ stranding) stranding consists of a central wire surrounded by one or more layers with lay direction reversed for successive layers, and with the same lay length for each successive layer. Normal direction of lay of the outer layer is left-hand.
Conventional concentric
stranding consists of a central wire surrounded by one or more layers with lay direction reversed for successive layers, and with different lay length for each successive layer. Normal direction of lay of the outer layer is left-hand.
19-WIRE COMBINATION UNILAY conductors are 19 strand constructions with a straight central wire, an inner layer consisting of six wires of the same diameter as the central wire, and an outer layer of six wires of the same diameter as the central wire alternated with six smaller wires. The smaller wires have a diameter of .732 times the diameter of the central wire. The 12 wires in the outer layer and the six wires of the inner layer all have the same length of lay and direction of lay.
The following strand constructions are possible:
concentric 7 Strands. Fig(1)
concentric 19 Strands. Fig(2)
concentric 37 Strands. Fig(3)7 Strands Unilay = 1 + 6 Strands as per shown in Fig (1)
19 ends = 1 + 6 + 12 Strands as per shown in Fig (2)
37 ends = 1 + 6 + 12 + 18 Strands as per shown in Fig (3)
etc.
7-end and 19-end strands are the preferred choices for cables used in electronics. The precise positioning of the individual wires makes for a smooth and even surface as well as an unvarying diameter.
Reversed lay direction / SZ stranding
S ➔ left hand lay
Z ➔ right hand lay
Strands with the same lay direction are generally called unilay.
Strand with opposing lay direction (SZ stranding) are called true concentric.
The roundness of a strand is driven by its lay length as well: