Things which are Important to avoid Strip Waviness defects:

"I" Unit

A Measure of Flatness

The Unit of measurement for Flatness is the "I" Unit.

One I Unit is a measure of the amount of elongation gaugation against the shortest measured
segment and is measured as a 1/100000th part.

One I Unit is defined as the Flatness error caused by differential length (of different fibers of strip)
of 0.001% or one part in 100,000.

For Example


If a 1,000mm long length of strip (at the centre) is rolled
with its edge 1000.01mm long, then the Flatness error between
centre and edge would be 1 'I' unit.



Shape Control Methods

  • Skewing Control
  • +/- Roll Bending Control
  • Intermediate Roll Shifting
  • S Roll Type Flatness Control
  • Thermal Crown Control
  • Selective Cooling







Some Strip Defects/Edge Waviness

Centre Buckles

Edge Waves

Long Center & Edge Waves
Piecrust Edge

Edge Wave
Flat Strip
Center Buckle