1. Jimmy K.C. Lam The Hong Kong Polytechnic University
CAD/CAM in Knitting (II) Advanced development in flat bed knitting machine
Jimmy K.C. Lam
The Hong Kong Polytechnic University

2. Learning Objectives Advantages of Schedule Knitting
Whole Garment Production
Digital Stitch Control System

3. Schedule Knitting
In shaped knitting, each piece (front body, back body, and both sleeves) must be knit separately and sewn together afterwards.
Normally, machine is programmed to knit one item at a time, first for body panel, back panel and sleeves.
This results in much wasted lead time for the sewing stage

4. Schedule Knitting (2)
Schedule knitting or sequential knitting, allows an entire set of fully fashion pieces to be knitted sequentially, for one garment at a time.
Machine is programmed to knit front, back and two sleeves at the same time for one garment piece.
In this way, post-knit sewing can be done immediately after the first garment is knitted, reducing the total time taken for an entire job.

5. Comparison between
Conventional Production
and schedule knitting

6. Whole Garment Knitting
Evolutionary Process in Knitwear Production

7. Whole Garment Knitting
As machines improved with evolving technology, the knitting methods started to change to yield higher productivity, increased efficiency, lower labour and material costs, and better consistency and quality.
The knitting production methods, have evolved for four major stages
Stage One: Cut and Sewn
Stage Two: Shaping
Stage Three: Integral Knitting
Stage Four: Whole Garment Knitting

8. Stage One Cut and Sewn Panel Knitting
This cut & sewn production involves knitting an entire panel of knit
Fabric to accommodate the front body, back body and sleeve.
This conventional method requires the patterns for the bodies and sleeves
To be cut out from the fabric and sewn together, involving seversal
Tedious post-knit operation.
Up to 40% of the original fabric may go to waste as cut-loss

9. Stage Two Shaping/ fully fashion knitting
Shaping allows the front and back bodies and sleeves to be knitted
According to specific pattern shapes for each piece.
Each pattern is shaped using only the amount of yarn necessary to knit that piece and seam allowances, so cut-loss is eliminated.
Trimmings and pockets still must be knit separately and post-knit linking and sewing are required

10. Stage Three Integral Knitting
Integral knitting uses shaping technology to knit pattern-shaped piece.
It improves shaping by “integrating” trimming, pockets and other accessories such as buttonhole to avoid sewing together these items. Great saving can be had in post-knit processing.

11. Stage Four Whole Garment Production
Whole garment or “complete garment” production is an entire garment is knit on the machine without any linking or sewing. Incredible cost-savings can be had as a result of eliminating all post-knit labour.
On demand knitting capability shrinks production lead time considerably.

12. Development in computerized V-bed machine (2)
Special needles development (compound needle and slide needle) to facilitate pattern flexibility and production efficiency
Special transfer jack and stitch presser development to knit complicated design and fabric
Development of new take down tension device for sequential knitting
Digital control loop length device to control fabric quality (so loop length will be the same for different panel)

13. Digital Stitch Control System
Before the invention of digital system, analogue knitting methods yielded inconsistent loop formation which resulted in variation in fabric size (length and width and fabric weight).
With digital stitch control system, tolerance is quoted to within +/- 1% which is crucial to shaping, integral knitting and whole garment production.
Uniform quality is achieved among different production batches, as well as for repeat orders.

14. Digital Stitch Control System (DSCS) Principle
As shown in the figure, the DSCS-equipped machine is programmed with the desired loop length, it monitors yarn consumption continuously and adjust yarn feed and tension through each course to yield consistency throughout the fabric.

15. Digital Stitch Control Device
It is located on both the RHS and LHS of V-bed machine.
The yarn consumption is monitored continuously so that any variation in loop length and knitting tension can be adjusted immediately.

16. 3-D Collar Knitting

17. 4-System Computer Flat Knitting Universal, Germany

18. Examples of Whole Garment Knitting

19. Collar Knitting
Seamless
Knitting
Hem Knitting

20. Whole Garment
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Variety