Forming Fabric Design

Question 1

List some design criteria for forming fabrics

Answer 1

Machine sketch
Speed range
Weight range
Paper grade
Information on previous fabric…

Question 2

What is the weft ratio? (forming fabrics)

Answer 2

Describes ratio of CD yarns on paper vs bottom side
More CD yarns on paper side = higher fibre support and retention
Less CD yarns on bottom side = lower wear potential

Question 3

Should the top side of a forming fabric be fine or coarse

Answer 3

Fine to allow more fibre support points and higher retention

Question 4

On a forming fabric what yarns wear first and how can we help this

Answer 4

Bottom CD yarns (weft). Should be thick

Question 5

What yarns on the bottom of forming fabric should be protected?

Answer 5

MD yarns (Warp). Structural integrity

Question 6

What are design requirements for hybrid former forming fabric?

Answer 6

Initial drainage needs to be correct. Too wet = crushing. Too dry before top unit = poor formation
Low internal bond so not too strong dewatering at start

Question 7

What are design requirements for gap former forming fabrics?

Answer 7

Often run at higher speeds causing misting and dirtiness so fabric should have low void volume to avoid carrying too much water.
Need high fibre support to improve retention