ROLLING TYPES AND DEFECTS

By | February 20, 2016

In this article we will discuss rolling types and defects.

  • FOIL ROLLING
  • RING ROLLING
  • FLAT ROLLING

FLAT ROLLING

In rolling types and defects topic, first of all here is flat rolling.

In this material is fed between two rollers that rotate in opposite direction.

Gap between rollers is less than the thickness of material, which cause it to deformation.

Due to decrease in thickness of material cause it to elongate.

The friction between material and rollers cause material to pushed .

Amount of deformation in a single pass is limited by friction between rollers.

Rollers can be slip if there is change in thickness is more.

In this the final products are

  • Sheet
  • Plate

The thickness of product is less than 6mm thickness.

Where as a heavy plates can be formed by using press, which is known as a forming

Rather than rolling.

Lubricants is also used to keep work piece from sticking to rolls.

FOIL ROLLING

it is special type of flat rolling and used to formation of foil. It consist of sheet metal material having thickness less than 200 µm. in this type of rolling the rolling is prefer in cluster mill because small thickness required small rolls diameter.it is an another part of rolling types and defects.

Mostly commonly product are aluminium foil.

RING ROLLING

Ring rolling is special type hot rolling ,increase the diameter of ring.

In this work piece is passed through two rolls called idle rolls and the ring  pressed from the  outside

With another roll called driven roll.  In this rolling the formation of  grain structure is circumferential

That gives better mechanical properties.

Application of ring rolling include

  • Rockets
  • Tubes
  • Pipes.

 DEFECTS

In hot rolling if the temperature is great cause cracking and tearing of material.

Surface defects during cold rolling

  • Lap
  • Mill shearing
  • Scabs
  • Seams
  • Slivers

 

Scab

                            Fig 1. Scab

Sliver

                          Fig 2. Sliver

 

 

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