Knitwear Technology Part One : Simple V-bed CAM selection Jimmy Lam Institute of Textiles & Clothing

Learning Objectives n V-bed machine CAM geometry n Double System Machines n Needles and Jacks selection n Pattern and limitation

Simple V-bed CAM geometry n All cams in V-bed machine are symmetrical on both side (Why?) n These cams include raising cam for moving the needles to tuck or knit position; and n Lowering cam and guide cam to control the stitch length

V-bed Cam geometry Sl :LHS Stitch Cam Sr :RHS Stitch Cam Al :LHS Raising Cam Ar :RHS Raising Cam B :Clearing Cam C:Guide Cam Can you tell the function of raising cam and stitch cam ?

Function of raising cam n For high and low butt needles, if raising cam is in full position –All needles will move up; n If in half position, only the long butt needles will move upward, short butt needles will miss n If the raising cam is out of action, all needles will miss

V-bed machine with transfer cam Transfer cam is used to push the needle to the highest position so that opposite needle can draw the loop from one needle bed to the other.

Transfer cam n The requirements for loop transfer are –Transfer cam; –Receiving cam; –Needle racking in ½ or ¼ pitch; and –Special transfer needle

Transfer action Loop is transferred from one needle bed to another needle bed via transfer cam and transfer needle

Double System Knitting with high/low butt needle

Double System Knitting n Double system means two knitting courses can be produced on one stroke of cam carriage. Two cam boxes are housed in the same carriage so two knitting courses can be produced

Can you name the following structure in double knit systems ? I I I I RR F F A A RH RR: All needles knitRH:high butt knit, low butt miss F: All needles tuckFR: high butt knit, low butt tuck A: All needles missFH: high butt tuck, low butt miss

Patterning n Knitting pattern on jacquard knitting machine depends on n Yarn carrier change (colour change); n Needle sett out; n Stitch selection; n Needle bed racking; and n Cam function selection (knit/tuck/miss/transfer)

Please explain why the following pattern cannot be produced on high/low butt needles

Needle and Jack selection

Needle and Jack n To increase the pattern scope, we can put jacks under the needles, and have the option to select pattern via needles and jacks

Needle and Jack selection Both needles and jacks are used to make this pattern

Discussion n Why knitting cam is normally symmetrical on both side ? n What is the limitation of simple needle and jack selection ? n How can multi-jack selection increase the pattern size ?