This document provides information about dimensional stability and geometry in weft knit fabric. It was presented by 7 students from the Textile department of Bangladesh University of Business & Technology. The key points discussed include how knitted fabrics are prone to changes in size and shape from wear and washing. It also discusses dimensional stability states, loop length, areal density, fabric cover, tightness factor, and spirality - defined as dimensional distortion where wale rows are not perpendicular to courses. Formulas are presented for factors that influence the angle of spirality, such as the number of feeders, loop shape, and number of active needles.

1. WEFT KNIT FABRIC GEOMETRY
PRESENTATION ON

2. PRESENTED BY
• Name with ID:
• Md. Enzamul Haque (022)
• Shawan Roy (023)
• Ahmmed Sharjin Sharif (024)
• Pankaj Roy (025)
• Kohinur (027)
• Saiful Hasan Sakib (030)
• Textile 5th Intake
• Section 1
• Bangladesh University of Business & Technology

3. DIMENSIONAL STABILITY
• Knitted fabric is so notorious for its tendency to
change size and shape in wear and washing that
to many people the phrase ‘ the dimensional
stability of knitted fabrics’ will be contradiction
in terms.
• The different dimensional stable states to which
the knitted fabrics are imposed, and
• The loop length of yarn in the knitted loop.

4. DIMENSIONAL CHARACTERISTICS
•

5. DIMENSIONAL CHARACTERISTICS
•

6. DIMENSIONAL CHARACTERISTICS
Constants for geometry of plain worsted knitted fabrics at different stable states (imperial unit)

7. DIMENSIONAL CHARACTERISTICS
Constants for geometry of plain worsted knitted fabrics at different stable states (SI unit)

8. AREAL DENSITY
•

9. FABRIC COVER
•

10. TIGHTNESS FACTOR
•

11. SPIRALITY
• Spirality is dimensional distortion in circular plain knitted
fabric.
• The lengthwise rows of stitches, called wales or needle
lines, should occupy a truly vertical line in the fabric &
should always be at right angles to the cross-wise course
of stitches.
• This perpendicularity of wales to the courses is frequently,
not the case & many times the wales may skew to the
right or left forming an angle, which appears in the form
of a twilled surface.
• This geometrical defect has termed spirality of knitting in
circular fabrics.
• The following fig. shows the fabrics with normal loop
position & with spirality having wales skewness.

12. THEORY OF SPIRALITY
•

13. THEORY OF SPIRALITY
•

14. THEORY OF SPIRALITY
• The above relationship shows that the angle of
spirality depends on
• 1.Number of feeders of the machine
• 2.Shape of the loop in a particular state of
relaxation and
• 3.Number of active needles in the machine
which depends on machine gauge and diameter

15. MEASUREMENT OF SPIRALITY
•