Knitwear Technology Part Two : Multi-jack, jacquard steel selection Jimmy Lam Institute of Textiles & Clothing
Learning Objectives n Multi-step jack selection n Pattern drum selection n Jacquard steel selection
Multi-step jacks selection n The earlier selection based on simple needle and jack (high/low butt) principle can only produce a very small pattern size. n To expand pattern, we have to put more jacks under needles. n Multi-step jacks selection (with 6 to 8 jacks) is an example. (Universal MC-410)
Multi-step jacks selection More jacks are put under the needles to increase the pattern size
Summary of pattern n No pattern costs, pattern jacks are set manually n Pattern jack setout cannot be saved, re- arrangement is needed for new pattern n Pattern time is jack set out time n Pattern width is narrow; n Pattern height depends on number of control card used.
n So far, we have discussed pattern (jacquard) selection by: –Hi/lo butt needles; –Hi/lo butt jacks and needles; and –Multi-step jack selection n To increase pattern size, we can use –Pattern drum ;and –Pattern steel selection
Pattern Drum and Jacks n Universal MC-M is the only machine offers pattern drum selection n The machine has two pattern drums, each drum has 72 pattern keys and each key has 36 tooth n The pattern height is 144 (2X72) courses and the pattern width is 36 wales (jacks are in diagional set out)
Principle n The drum will be lift up and give forward and backward racking for new selection when the carriage reaches the right or left end of the needle bed n If teeth remains in the pattern key, it will push the pattern jack to sunk below the needle bed, results in miss loop. n Only when jack in upward position, the jack butt can select by needle bed for knitting action.
Techno-economics of pattern drum selection n We concern with pattern preparation time and pattern cost n Pattern Drum Selection –Pattern size 144 courses X 36 wales –Cost of 144 courses gives 144 pattern keys –If each key is @5.00, total cost is 144X5=$720 n Pattern time –One pattern key takes 25 seconds –144 pattern keys take 25 sec X 144 = 1 hour
n If produce by jacquard steel selection n Pattern cost is equal to labour cost n Pattern time –One jacquard steel takes 20 min, a 144 jacquard steels take 48 hours –About 6 days wages, roughly $1500-2000 n Therefore, for small pattern, pattern drum uses one hour and half the money on jacquard steel. In addition, storage of pattern drum/keys are lot easy
Example : Four colour pattern on jacquard steel
Jacquard Steel (single system) n Hole in the steel = needle miss n No hole/bolcked= needle selected n For a 3 colour rib jacquard pattern with 30 surface courses on single jersey, it will take 90 jacquard steels
Jacquard Steel (Double System) n Requirement : Two rows of holes on jacquard steel, one for each knitting system; n Three cam tracks for each knitting system, one for the needle, and two for the jacks n The jacquard steel selection is done when the cam carriage is away from the needle bed. n The time available is only a fraction of second, therefore, vibration from the heavily jacquard roller and steel could cause a wrong pattern on fabric.
Discussion n Discuss the advantages of pattern drum selection n Discuss the advantages and limitation of jacquard steel selection