Latch needle | Characteristics & Uses of Latch needle

Latch needle were used on raschel and crochet machines. The latch needle is composed of a curved hook, a latch, or tumbler, that swings on a rivet just below the hook, and the stem, or butt. It is sometimes called the self-acting needle because no presser is needed; the hook is closed by the pressure of a completed loop on the latch as it rises on the shaft. Needles differ greatly in thickness, in gauge, and in length. Pierre Jeandeau patented the first latch needle (also known as the tumbler needle) in 1806 but there is no evidence of its practical use.There is also no evidence that the pivoting of a broken pocket knife blade led to the development of the latch spoon.

Latch Needle Characteristics:

1. Most widely used in weft knitting.
2. More expensive needle than the bearded needle.
3. Self acting or loop controlled.
4. Work at any angle.
5. Needle Depth determines the loop length.
6. Variation of the height of reciprocating produces knit, tuck or miss stitch.

Uses of Latch Needle: Latch needle are widely used in –

1.  Double Cylinder Machine,
2.  Flat Bar Machine,
3.  Single Jersey Circular Knitting Machine,
4.  Double Jersey Circular Knitting Machine.

The elements which characterise this type of needle are the following:

• the stem: the stem is the main part of the needle and its thickness is proportional to the machine gauge; the stem is arranged between the rods and the pockets of the needle bed, which acts as a guide; the stem can be bent to allow the needle to keep the position set by the selection mechanism.
• the butt: the butt is the stem section in contact with the cams or the selection mechanism; cams and selection mechanism generate the upward and downward strokes of the needle: the height of the butt can vary according to the different operating possibilities. A latch needle can have one or more butts, arranged at different levels.
• the hook: the hook is the upper end segment of the stem. It picks up the yarn fed by the thread guide to form the stitch. Height, diameter, length, thickness, shape and position are the main parameters of a hook.
• the latch holder: the latch holder is the part of needle carrying the latch pin. The latch can be assembled in three different ways:
  1. it can be screwed (this manufacturing technology is rather complex);
  2. it can be “R” standard pressed (when it has a straight hole);
  3. it can be “A” angle pressed (when it has a slant hole).
• The latch: it is shrunk on the pin and it can freely rotate in both directions; its length determines the stroke the needle must cover to form the stitch. At the latch end there is a recess (the “spoon”), which allows the thickness resulting from the mating of the latch and the hook to be reduced. The yarn must fit under the open latch but the surface on which the loop must slide must not be too thick; for this reason, a special pocket, or “throat”, is machined on the needle stem.

- See more at: http://www.textileschool.com/articles/341/knitting-needles#sthash.EOJglenX.dpuf

The elements which characterise this type of needle are the following:

• the stem: the stem is the main part of the needle and its thickness is proportional to the machine gauge; the stem is arranged between the rods and the pockets of the needle bed, which acts as a guide; the stem can be bent to allow the needle to keep the position set by the selection mechanism.
• the butt: the butt is the stem section in contact with the cams or the selection mechanism; cams and selection mechanism generate the upward and downward strokes of the needle: the height of the butt can vary according to the different operating possibilities. A latch needle can have one or more butts, arranged at different levels.
• the hook: the hook is the upper end segment of the stem. It picks up the yarn fed by the thread guide to form the stitch. Height, diameter, length, thickness, shape and position are the main parameters of a hook.
• the latch holder: the latch holder is the part of needle carrying the latch pin. The latch can be assembled in three different ways:
  1. it can be screwed (this manufacturing technology is rather complex);
  2. it can be “R” standard pressed (when it has a straight hole);
  3. it can be “A” angle pressed (when it has a slant hole).
• The latch: it is shrunk on the pin and it can freely rotate in both directions; its length determines the stroke the needle must cover to form the stitch. At the latch end there is a recess (the “spoon”), which allows the thickness resulting from the mating of the latch and the hook to be reduced. The yarn must fit under the open latch but the surface on which the loop must slide must not be too thick; for this reason, a special pocket, or “throat”, is machined on the needle stem.

- See more at: http://www.textileschool.com/articles/341/knitting-needles#sthash.EOJglenX.dpuf

The elements which characterize this type of needle are the following:

The stem: The stem is the main part of the needle and its thickness is proportional to the machine gauge; the stem is arranged between the rods and the pockets of the needle bed, which acts as a guide; the stem can be bent to allow the needle to keep the position set by the selection mechanism.

The butt: the butt is the stem section in contact with the cams or the selection mechanism; cams and selection mechanism generate the upward and downward strokes of the needle: the height of the butt can vary according to the different operating possibilities. A latch needle can have one or more butts, arranged at different levels.

The hook: the hook is the upper end segment of the stem. It picks up the yarn fed by the thread guide to form the stitch. Height, diameter, length, thickness, shape and position are the main parameters of a hook. The latch holder: The latch holder is the part of needle carrying the latch pin. The latch can be assembled in three different ways:

• It can be screwed (this manufacturing technology is rather complex);
• It can be “R” standard pressed (when it has a straight hole);
• It can be “A” angle pressed (when it has a slant hole)

The latch: It is shrunk on the pin and it can freely rotate in both directions; its length determines the stroke the needle must cover to form the stitch. At the latch end there is a recess (the “spoon”), which allows the thickness resulting from the mating of the latch and the hook to be reduced. The yarn must fit under the open latch but the surface on which the loop must slide must not be too thick; for this reason, a special pocket, or “throat”, is machined on the needle stem.

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