Knitting Technology

Introduction

By using the three methods of needle manipulation, namely knitting, tucking and missing (described in the introductory module, Introduction to knitting), together with stitch transfer and racking it is possible on V-bed machines to produce the four fundamental fabric structures already described:

• Plain knitted fabrics
• Rib knitted fabrics
• Purl knitted fabrics
• Interlock knitted fabrics.
  
  Plain knitted fabric can be manufactured on either the front or rear beds of the machine, or two plain knitted fabrics may be produced at the same time on both front and rear beds, these may be joined at the selvedge if required, as in tubular knitting.
   
• Rib fabrics are conventionally produced by arranging the needles in rib gaiting and knitting on both beds simultaneously.
  

  • Purl fabrics can be manufactured by knitting on all needles on one bed and then transferring all the loops to empty needles on the opposite bed before knitting the next course (row).

  • Interlock fabrics can be manufactured by arranging the needles in interlock gaiting or half rack (see racking below) and knitting on even needles on one bed and odd needles on the other for one course and then reversing the needle selection for the second course and so on. Care must be taken to make the selection so that needles from the front and rear beds do not collide.

  • By using different combinations of the four basic structures together with the patterning and structure modification techniques described below it is possible to use a V-bed machine to manufacture an infinite variety of fabrics with an amazing range of appearances, properties and performance. 
  • The modern V-bed machine is the most flexible knitting system (other than ‘hand-knitting'), that has ever existed and its full potential is only just beginning to be explored by the industry.

  Click this link to view picture of Rib Knitted Fabric:

  http://www.knitepedia.co.uk/browse/knit_tech/knit_tech/V_bed_patterning/viewer/K_3_1_Vbed_machine_fabric_structure_and_patterning_img_2074_1.htm
  
  

  Use of the four basic structures

  The overwhelming majority of V-bed machines installed around the world are used for making garment lengths or garment panels. The overwhelming majority of garments produced on these machines are made-up of combinations of the first three of the four basic structures described above.
  
  

  Plain knit fabric

  Plain knitting is most frequently used for the ‘body' of garments because it is rapid to knit and, due to its light weight, cheap to produce. It is a flat uniform fabric with good stretch and moderate recovery properties. Because of the unbalanced torsional forces in the loop structure plain knit fabrics curl and roll from the edges, especially when cut, making sewing and linking more difficult than for balanced fabrics such as rib.
  
  

  Rib structures

  A whole sequence of different rib structures can be made depending on the number of adjacent needles that knit together before the yarn moves to the other bed. For example 1 x 1 rib knits on only one needle before the yarn moves to the other bed. 2 x 2 rib knits on two needles, 3 x 3 rib on three needles and so on. Non symmetrical ribs such as 2 x 4 may also be used. The lower orders of ribs such as 1 x 1 and 2 x 2 show very good stretch and recovery properties and are therefore much used for the waist and cuffs of garments. The higher order ribs such as 5 x 5 and 6 x 6 are progressively closer to plain fabric and their properties are closer to those of plain fabric. Higher order non symmetrical ribs such as 6 x 2 may be used for the body of the garment as they are much closer to plain fabric in their properties and cost but with an interesting vertical stripe effect.
  
  

  Purl structures

  In a similar way to rib structures a whole sequence of purl structures may be produced from the basic 1 x 1 purl where stitch transfer takes place after every course (row) to higher order purls such as 4 x 4 and 6 x 6 which behave increasingly like plain fabric but with pronounced horizontal stripes. Purl structures, especially the lower order structures, do not have good stretch properties but they do have good recovery properties and are therefore suitable for the body of garments.
  
  

  Interlock structures

  Interlock structures are not frequently manufactured on V-bed machines largely due to their slow rate of production as they require two rows of knitting for every horizontal row in the fabric.
  
  

  Knitted loop transfer

  
  

  
  

  The direct needle loop transfer stitch is produced by the transfer of a loop from one needle to another in the opposite bed.
  1. The transferring needle is at knitted loop transfer height.
  2. The hook of the receiving needle is penetrating the knitted loop.
  3. The knitted loop has opened the latch of the receiving needle.
  4. The transferred loop is in the receiving needle hook.

  
  Loop transfer may be used to:
  

  1. Produce shaped garment panels
  2. Produce a design or pattern
  3. Change the stitch structure
  4. Knit purl structures

  
  

  • The question of shaping and garment manufacture will be addressed in the module, Garment manufacture on v-bed machines.

  • The knitting of purl structures is the straightforward use of loop transfer to remove the loop from the needle on which it was knitted and place it in the hook of the opposing needle in the opposite bed so that the next stitch can be drawn through the structure in the opposite direction.

  • The use of loop transfer to change the structure most frequently applies in changing from rib knitting to plain knitting when the loops from one bed are transferred to the other bed so that knitting can continue on one bed only. 
  • This most frequently occurs when the body of the garment is to be produced in plain knit and the welts and rib is produced in rib. Equally loop transfer may be used to change from a plain knit structure on one bed to a rib structure on two beds by transferring every alternate needle loop from the plain knit bed to the other bed.

  • The use of loop transfer to create pattern and surface or structural effects can vary from the very subtle drop-stitch patterning where a loop is transferred out of the wale where the drop stitch will be selected to stop the drop stitch laddering, to large complex structures such as cables and to all over transfer patterning as seen in Aran designs.

  
  

  Jacquard knitting

  • Individual needle selection enables colour jacquards to be produced, either as single fabrics (with floats on the reverse, linking each colour area, which can be quite long and can snag, or can be tucked in to the face at regular intervals to limit the float length) or as rib fabric jacquards. The latter are more stable and have a variety of backings, including striped, birds-eye or ladder-back.

  • It is important to remember that in jacquard knitting the colours that do not show on the face of the fabric are floating either in the middle of the structure for rib jacquards or on the back of the fabric for single jersey jacquards. For this reason as the number of colours in the design increases the weight and thickness of the fabric rapidly increases and for reasons of cost and fabric properties the number of colours is usually limited to 2 or 3. 

  • A more detailed description of jacquard knitting will be given in the module Graphical representation of knitting.

  • The use of jacquard patterning within V-bed garments has been infrequent during the last 30 years and is driven by fashion trends.

  
   The following illustration shows the hidden colours floating within a three colour rib jacquard structure with a striped back.

   http://www.knitepedia.co.uk/browse/knit_tech/knit_tech/V_bed_patterning/viewer/K_3_1_Vbed_machine_fabric_structure_and_patterning_img_2103_1.htm
  
  http://www.knitepedia.co.uk/browse/knit_tech/knit_tech/V_bed_patterning/viewer/K_3_1_Vbed_machine_fabric_structure_and_patterning_img_2102_1.htm
  
  
   The following knitting modules progress from the basic concepts necessary to understand the essential features of knitting machines and knitted structures through to the advanced knitting principles required to understand and influence the design and development of sophisticated engineered technical products. Click on the link below to start the course.
   http://www.scribd.com/doc/53515189/Knitting-Technology