The Electronic Needle Selection V-bed System

1. The Electronic Needle SelectionV-bed System Jimmy Lam Institute of Textiles & Clothing

2. Learning Objectives • Disadvantages of mechanical needle selection • Advantages of electronic needle selection • Comparison between mechanical and electronic V-bed machine • Ref:Knitting Handbook Vol. 9, Jacquard Mechanism on V-bed pp38, by K.H. Yue

3. Disadvantages of Mechanical Knitting • Can you name any limitation of mechanical V-bed machine for jacquard fabric ?

4. Disadvantages • Restriction on pattern area, and freedom of design • Pattern time and cost is directly proportional to the pattern size • Machine with more than double systems is almost impossible • Prolonged time is required in pattern correction and modification

5. Electronic Needle Selection • V-bed machine with electronic needle selection is known as electronic V-bed knitting machine • It builds with computer system to control all machine operations according to the knitting instruction. • Needle selection is only part of the programme for jacquard knitting • Can you name any other operations for electronic jacquard selection ?

6. Advantages of electronic needle selection • 1) Huge pattern size • The electronic V-bed machine can have pattern areas of 125 X125 stitches, 256 X 256 stitches; 512 X 512 stitches and 1024 X 1024 stitches. In fact, the pattern areas are governed by machine memory and is expandable.

7. Advantages • 2) Fast and low pattern cost • Patterning for electronic V-bed machine has to be done on specific Computer Aided Design (CAD) System. To produce a jacquard pattern on CAD system is fast and simple. The pattern can be input to system by keyboard, free-hand drawing on the graphic tablet or through scanner. Together with the instruction in specific computer language.

8. Advantages • The jacquard pattern is then transferred to a data carrier for knitting machine to read and store. If overhead of the CAD system is not involved, the patterning cost is data carrier cost (tape or floppy disk) plus the few hours labor cost. • In addition, for mechanical V-bed machine, the patterning cost is multiplied by number of machine involved. For electronic V-bed, this cost id divided by the number of machines of the same model, gauge and width.

9. One CAD Design Centre can serve a number of computerized knitting machine

10. Advantages • (3) Multi-System machine. • Modern electronic V-bed m/cs are built-with compact cam to reduce weight and width of cam carriage. This allows more knitting systems to be installed and higher production rate. • However, increasing the number of knitting systems will increase the weight of carriage which will cause difficulty on repairing when it is getting to heavy. In addition, it will increase the costs of knitting machine.

11. Advantages • (4) Pattern correction and modification • All modern V-bed m/c has built-in computer and monitor as standard equipment. The input data (pattern/design) from independent design system can be adjusted or modified right on each individual m/c. These correction and modification only require work on the m/c keyboard and store on computer.

12. A simplified CAD/CAM process for computerized knitting machine

13. Comparison between Mechanical and Electronic V- Bed machines

14. A German Stoll Design Workstation Note that the input process can be done via keyboard, graphic tablet and digital camera

15. Tape is used as • a storage device A German Universal Design Workstation

16. Comparison • (1) Knitting Speed • With the exception of machine down time for pattern change, .both systems have similar machine speed. However, the electronic V-bed m/c has stroke reduction for narrow panel. In addition, the pattern change for e-m/c is about 15 mins., about 30% of the mechanical machines with jacquard steels.

17. Comparison • (2) Overheads • The overhead for electronic V-bed machine is a lot higher- than mechanical one. In addition, a design centre (CAD) must be used with the electronic machine. Therefore, this high capital costs limits the manufacturers to produce high profit knitwear only.

18. Comparison • (3) Pattern preparation time & cost • The electronic machine with design centre is superb in this area. Both the preparation time and cost of design is less than mechanical one. See Figure • (4) Freedom of Design • The modern electronic V-bed with extra functions like stitch presser, comb take down, intarsia yarn carriers allows the machine to knit far more complicated pattern with huge pattern data.

19. Knitting cost increases with number of mechanical machines. But it remains the same for computerized machines

20. Pattern time increases with number of mechanical machines but decreases with computerized machines

21. Comparison • (5) Training of new hands • All modern machines are design with one common goal, to build a machine easy to use and difficult to go wrong. Therefore, training of new hands is lot easier for new machine. • (6) Technician and machine operator • No problems on human resource for electronic V-bed -industries as all young people prefer to work on modern hi- -tech industries with better working condition and higher paid than the mechanical one.

22. Comparison • (7) Maintenance • The modern practice on maintaining the electronic parts. is to replace instead of repair when malfunction occurred; thus it is lots easier but the costs is higher.

23. Discussion • What are the major advantages of electronic needle selection knitting machine ? • What are the limitation of electronic needle selection knitting machine?