Textile & Fashion World

There are three methods of forming the newly-fed yarn into the shape of a needle loop: 

1. (Fig. 1) – by sinking the yarn into the space between adjacent needles usingloop forming sinkers or other elements which approach from the beard side.Theaction of a straight bar frame is illustrated. (Other obsolete circular bearded needle machines such as the sinkerwheel and loopwheel frame employ the sametechnique.) The distance SL, which the catch of the sinker moves past the beardside of the needle, is approximately half the stitch length,

The Under Lap

The underlap shog occurs across the side of the needles remote from the hooks on the front of single-needle bar, and in the centre of double-needle bar, warp knitting machines. It supplies the warp yarn between one overlap and the next (Fig.A).The underlap shog generally ranges from 0 to 3 needle spaces, but it might be 14 needle spaces or more depending upon the design of the machine and the fabric structure (although efficiency and production speed will be correspondingly reduced with long underlaps).

A.Under lap shog

Underlaps as well as overlaps are essential in warp knitted structures in order to join the wales of loops together but they may be contributed by different guide bars.

The Closed Lap
A closed lap is produced when a subsequent underlap shogs in the opposite direction to the preceding overlap, thus lapping the same yarn around the back as well as around the front of the needle (Fig.B).

B.Closed Lap

The Open Lap
An open lap is produced either when a subsequent underlap is in the same direction as the preceding overlap (Fig.C) or an underlap is omitted so that the overlap of the next knitting cycle commences in the needle space where the previous overlap finished. Closed laps are heavier, more compact, more opaque, and less extensible than open laps produced from the same yarn at a comparable knitting quality. 

 

 

http://textilelearner.blogspot.com/2012/03/introduction-of-under-lap-closed-lap.html#ixzz2OGnRZJdZ

The needles are the most important stitch forming elements. They are displaced vertically up and down and are mounted into the tricks or cuts of the knitting cylinder.
There are three types of needles namely:
1. Latch needle
2. Spring bearded needle 

3. Compound needle.

We can divide a needle into three main parts:
A. the hook, which takes and retains the thread tube looped;
B. the hook opening and closing device, that allows the hook to alternatively take a new thread and release the previous one;
C. a system allowing the needle to move and form the loop.