SKIN PASS AND DEFECTS

By | February 20, 2016
Skin pass mill

                                 fig 1. Skin Pass Mill

In this article we will discuss skin pass and defects.

Rolling is used to reduced the thickness and to make the thickness uniform.

Skin pass is another type of rolling process.

Skin pass rolling is defined as a process in which fine structure give to the newly generated grain

After annealing process so that it become useful for forming operation.

In case of skin rolling also known as a skin pass having less reduction around 0.5-1 %.

It produced smooth surface, uniform thickness, and reduced the yield point.

It is used where ductility is required.

DUCTILITY  is a material that can be stretched thin wire when tensile stress is applied.

skin pass mill fig.

                           Fig 2. Mill

Skin pass rolling is done for following parameters:

To achieve the optimum mechanical properties

(Hardness, YS, —–)

To prevent occurrence of stretcher strains in annealed steel

To impart desired surface finish – “matte” on the strip surface

To improve strip shape

To reduced the yield point

Mechanical Properties are controlled by regulating the % elongation during skin passing

% Elongation depends on the grade of the CR steel.

Range –

Stretcher Strain removal is achieved  through suppression of the yield point elongation during

skin passing

 

Before SkinPass

                     Fig 3. Before SkinPass

After Skin Pass

                    Fig 4. After Skin pass

                                                                             

SKIN PASS AND DEFECTS

  • Hole mark
  • Wrinkle
  • Roll mark
  • Wavy
  • Sliver
  • Edge cut
  • Sticky
  • Pick up mark(use of rubber pad)
  • Seam line
  • CBL(COIL BRAKE LINE)
  • RIS(ROLLED IN SLAG)

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