Friday, December 16, 2016

Knitting Action of Latch Needle | Loop Formation Techniques of Latch Needle

Knitting Action of Latch Needle:
Knitting action or loop formation techniques of latch needle is illustrated following figure. The loop forming process is divided into nine operations.
  1. Clearing
  2. Yarn laying or feeding
  3. Under lapping or yarn drawing
  4. Pressing
  5. Landing
  6. Joining
  7. Casting-off or knocking-over
  8. Loop forming and sinking, and
  9. Loop draw -off
Knitting action or loop formation techniques of latch needle
Fig: Knitting action or loop formation techniques of latch needle
1. Clearing (a): The process of stitch formation is started by the clearing operation. Its aim is to draw the old loops behind the needle latch. Clearing is effected during needle lift. The old loop is retained by the beak of the sinker shifted to the cylinder center so as to avoid its displacement together with the needle. At the time of clearing, the sinker remains immobile. Clearing is completed when the needle reaches its upper position.

2. Yarn laying or feeding (b): In the course of needle downward motion, the hook takes hold of yarn coming from the yarn guide and effects it's laying. At the moment when laying is started, the sinker beak must retreat a little from the cylinder center so as not to further impede the loop forming process.

3. Under lapping or yarn drawing (c): Further movement of yarn just laid and its forwarding under the needle hook is called under lapping or drawing. Actually, drawing is performed simultaneously with the yarn laying when the needle starts to move down.

4. Pressing(c): The aim of pressing is to close the needle hook with the yarn laid in it. When the needle lowers, its latch contacts the old loop lying near the knock-off plane and retained from lowering by the sinker chin. The old loop interacts with the latch and closes it.

5. Landing (d): The essence of this operation consists in shifting the old loop on the closed latch. The landing operation in latch needle machine begins simultaneously with pressing.

6. Joining (d): At joining, the new yarn comes in contact with the old loop. Joining is accomplished simultaneously with the beginning of casting-off.

7. Casting-off or knocking-over (e): The casting-off operation consists in the retreat of the old loop from the needle hook.

8. Loop forming and sinking (e & g): Loop forming consists in drawing the yarn grasped by the needle through the old loop retained by the sinker chin. The lower the needle moves in respect to the knock-off plane at kinking, the longer is the formed loop and the less the stitch density.

9. Loop draw-off (f):
The aim of this operation is to draw the old loop behind the needle back. Draw-off of new loops is effected by sinker throats. At the same time, exercising their action on the knitted fabric, the chins of sinkers with draw the old loops from the knitting zone. The machine take-down mechanism promotes this operation.

Loop draw-off is completed when the apex on the interior side of the hook head reaches the knock-off plane level, which corresponds to the initial position for the described loop forming process.