1. Warp Knitting

2. Warp Knitting
Warp knit fabric is produced from a set of warp yarns, normally using at least one yarn per wale, knitted parallel to each other down the length of the fabric.

3. In warp knit yarns run vertically
It involves the preparation of warp beam
Yarns zigzag from side to side along the length of the fabric
One yarn for each needle
Yarns to be wrapped around the needle to form loops and stitches

4. Weft Knitting vs Warp Knitting

5. Weft Knitting vs Warp Knitting
Yardage, shaped garments, garment parts and finished products can be produced.
Fabric tends to stretch in width and length.
Fabric may run or ravel
Rapid changeover to new design
Production may be flat or circular
Produces yardage only
Limited stretch. Some in width, less in length
Do not run or ravel easily
Slower and more costly changeover to new designs
Flat only

6. Warp Knitting

7. Warp Knitting Machine

8. Warp Knitting Machine

9. Warp Knitting Machine

10. Warp Knitted Fabric
The warp knitted fabric is formed by knitting the warp yarns on adjacent needles course by course and intermesh the loops with the neighbouring yarns to form fabric.

11. From the diagrams below, it is clear that if a warp knit fabric
required 1000 wales, then there must be 1000 warp yarns on the
beam and slightly more than 1000 needles on machine

12. Made of two parts: The overlap The underlap
Warp Knitted Loop
Made of two parts:
The overlap
The underlap

13. Guide Bar Movement

14. The Overlap
Formed by the yarn being wrapped around the needle and drawn through the previous loop.

15. The Underlap
The length of yarn connecting the loops is called an underlap. It is formed by the shogging movements of the ends across the needles.

16. The Course
A course (2) is a horizontal row of loops formed by the needles during one knitting cycle. In warp knitting, all the needles perform the knitting action simultaneously so that one knitted course is formed across the whole width of the knitting machine for every turn of the main shaft.

17. The Wale
The wale (3) is vertical column of loops formed by a single needle. The number of wales in the fabric equals to the number of needles

18. Knitting Elements
Warp beams : to supply yarn to warp knitting machine. Controlled by shaft for even tension
The guide bar: Threading yarn to produce lapping movement. Minimum number : 2, move at opposite direction

19. Continue…
Yarn Guides: thin metal plates with hole which the yarn passes thru it, held together as a single unit in a metal lead
Metal lead attached to the guide bar
Guide has the same gauge as the needles

20. Knitting Elements in Units
The knitting elements (needles, sinkers, guides) are usually cast in units, 1 inch long which in turn are screwed into their respective bars (needle bar, sinker bar and guide bar).

21. Pattern Control Unit
The development of a pattern on warp knitting machine is a combination of
colour yarn pattern on warp beams;
warp thread setting on guide bars; and
lapping movement of the guide bars
For a simple single guide bar, single colour fabric, the structure is based on the lapping movement of the guide bar.

22. Guide Bar Movements
Lapping motion:
Swinging motion
Shogging motion

23. Swinging Motion
Arc from front of machine to the hook side and a later return swing
Occurs between adjacent needles
Is a collective movement for all the guide bars as they pivot on a common rocker shaft
The two swinging movements produce the two side limbs of the warp knitted loop

24. Shogging Motion Occurs parallel to the needles bar
Extent, timing, direction of underlaps and overlaps controlled for each guide bar by its own pattern chain links or pattern wheel
Produces underlaps and overlaps

25. Chain link: control the guide bar either right and left or front and back. Numbering: 0,1,2,3….or 0,2,4,6….
Different Height of
Links control the lapping
movement

26. COMPARISONS OF TRICOT AND RASCHEL KNITS
Machinery : use spring beard, latch or compound needles
Fine gauge only
Fine denier filament and textured filament
Simple design and small geometrics
Uses: Lingerie, swimwear, sleepwear, bonded backnig fabric, sportwears, upholstery, skirt n blouses
Latch needles
Fine to course gauge
Spun and filament, all count and denier
Large and intricate designs, but not as versatile as weaving or weft knitting
Uses: laces and trim, nets, dress fabrics, sweater fabrics, thermal kint for underwear, blankets, curtains

27. Example Lapping movement of Half Tricot: 1-2/1-0
“1-2” indicates the guide bar is doing overlap from needle
position “1” to “2” ie. From right to left for one needle
“1-0” indicates the yarn is fed to the needles from the left to
right for one needle space.

28. The last example only shows one warp thread on one guide bar
for a repeat structure. When thousands of warp threads are on the same
guide bar, and all the warp threads are doing the same movement, a
knitted fabric is formed

29. Basic combination of overlap and underlaps
All warp knit fabric structures are composed of both overlap and underlap

30. 1) Overlap Only
In this group, the guide bar only feed yarn to the same needle all the time.
The result is that each needle knits a chain of stitches.
Example: 1-0/01, known as pillar stitch
A pillar stitch is not a fabric, but is commonly used with other lapping movements to form a fabric.

31. Pillar Stitches
Formed when needles are lapped continuously by the same guides. Since the guides do not lap the adjacent needles, there are no sideways connections and no fabric is formed.

32. Two types of Pillar Stitch
Closed Pillar Stitch
1-0/1-0
Open Pillar Stitch
1-0/0-1

33. 2) Underlaps Only
Underlap alone cannot form into a fabric and is commonly used with other lapping movements.
If a guide bar only made underlaps in a multi-guide structure, this guide bar is called inlay bar and the warp are called inlay yarn, which never form into loops but only “tie-in” at the back of the fabric.

34. 3) Overlap with underlap When overlap and underlap are worked together, two type of fabrics can be formed
1. When overlap and underlap are moving the same direction, an open lap fabric will be formed.
2. When overlap and underlap are moving in opposite direction, closed lap will be produced

35. 1 X 1 Open Lap Fabric
1 X 1 Closed Lap Fabric

36. 4) Only underlap no Overlap
This seems to be warp float in the fabric.
The guide bars give no lateral movements for a few courses in the repeat, laying the warps straight in the fabric.
For a multi guide bar fabric, it is used to hide colour warps at the back for a colour pattern.

37. 5) Neither Overlap Nor Underlap (miss-lapping)

38. Single Guide Bar Fabric

39. Warp structures with a single set of guide bar
Half Tricot

40. Half Tricot Also known as 1 X 1 closed lap
The 1 X 1 lap is the basic formation of warp knit fabric.
The guide bar feeds yarn on a needle in the first course, and then it moves sideways to feed yarn on the neighbouring needle in the second course and repeat
All the warp knit fabrics are formed in the similar manner, except that there might be more guide bars used, more courses per repeat, or different underlaps and different direction of guide bar shogging.

41. Modification of Half Tricot
The difference between these three fabrics is the amount of guide bar shogging for underlaps.
Fabric weight: 3x1 > 2x1 > 1x1
Finished Width: 3x1 < 2x1 < 1x1

42. Disadvantages of single guide bar structures:
Low strength,
Lack of stability,
Poor covering power,
Distortion caused by loop inclination.

43. Warp structures with two sets of guide bars:
More balanced structures are achieved by having two sets of warp threads underlapping in opposition from each other so that underlaps of each enter and leave from opposite sides of the head loop.

44. Warp structures with two sets of guide bars

45. Examples : Full Tricot
This structure is actually knitting two “half tricot” together with two bars moving in opposite direction.
This is a balanced structure, the two set of warp yarns are doing their overlap in opposite direction. This result in perfect upright loops in the fabric surface.
BGB: 1-2/1-0
FGB: 1-0/1-2

46. Technical face: fabric side with the loops showing on the surface.
Full Tricot
Technical face: fabric side with the loops showing on the surface.
Technical back: fabric side with the underlaps showing on the surface.

47. Locknit Most two guide bar structures are not balanced.
Although all structures have their overlap and underlaps in the opposite direction, but the underlap displacements of the two bars are different.
Locknit is one of the examples.
The FGB makes a longer underlap than BGB, and the result is the fabric will give lower sideway elasticity than tricot.
BGB: 1-2/1-0
FGB:1-0/2-3

48. Reverse Locknit
FGB: 1-0/1-2
BGB:2-3/1-0

49. Sharkskin FGB: 1-0/1-2 BGB:4-5/1-0
The Sharkskin which has a longer underlap
4-5/1-0 on the BGB, will be even heavier in weight

50. Queen’s Cord Queen’s cord is a very stable structure.
The pillar stitches act as warp yarns and the long underlaps act as weft yarns in the fabric.
Therefore, its dimensional stability should be near to the woven fabrics.
FGB: 1-0/0-1
FGB: 2-3/1-0

51. Write down the lapping movements, chain notations for the given loop diagrams

52. Single Atlas
A typical single guide bar fabric with horizontal stripe effect
The lapping movement of guide bar moves in one direction for a number of courses and then return; this changes the direction of inclination of loops.

53. Double Atlas
Combination of two pieces of single atlas knitting together with opposite lapping direction.
The two guide bar (double atlas) will give a solid vertical wales and is more stable than single atlas.
Normally double atlas is knitted with colour patterns.

54. Eyelet Formation Vertical dotted lines = location of holes
FGB=2-3/2-1/1-0/1-2
BGB=1-0/1-2/2-3/2-1

55. Marquisette Curtain Net
The 2 bar Marqiosette os a see through net fabric composed
of square cells, is used for low cost curtain net.
FGB:1-0/0-1
BGB:0-0/1-1/0-0/3-3/2-2/3-3

56. Raschel Lace

57. Examples (Laces)

58. Examples (Laces)

59. Examples (Laces)

60. Raschel Warp Knit Lace, pantyhose