Basics of rolling operation and nomenclature of rolled products
INTRODUCTION
Lamination is classified according to the temperature of the laminated metal. If the temperature of the metal is above the recrystallization temperature, the process is called hot rolling. If the temperature of the metal is below the recrystallization temperature, the process is called cold rolling. In terms of utilization, hot rolling processes more tonnage than any other manufacturing process and cold rolling processes the most tonnage of all cold working processes.
Rolling Operation
There are many types of rolling processes, including ring rolling, roll bending, roll forming, profile rolling and controlled rolling.
In a rolling mill coupled to a steel mill, the starting point is a molten steel ingot that is progressively decomposed into blocks, billets and plates. The slabs are subsequently hot rolled into sheets, plates, rods, bars, rails and other structural shapes such as angles, channels, etc. The conversion of steel into commercially important sections is usually done in another rolling mill called a commercial rolling mill.
Lamination is a very convenient and economical way to produce commercially important sections. In the case of steel, around three-quarters of all steel produced in the country is sold as rolled products and the remainder is used as forgings, extruded products and castings. This shows the importance of the lamination process.
NOMENCLATURE OF LAMINATED PRODUCTS
Rolling Nomenclature
The following nomenclature is in common use:
(i) Flowers:
It is the first product obtained from breaking down Ingots. A flower has a cross section that varies in size from 150 mm square to 250 mm square or sometimes 250 × 300 mm rectangle.
(ii) Slip:
A billet is the next product rolled from a flower. Billets range from 50mm square to 125mm square.
(iii) Slab:
The slab has a rectangular section with a thickness ranging from 50 to 150 mm and is available in lengths of up to 1.5 meters.
(iv) Plate:
A board is usually 5 mm or more thick and 1.0 or 1.25 meters wide and 2.5 meters long.
(v) Sheet:
A sheet is up to 4mm thick and is available in the same width and length as a board.
(vi) Plan:
Flats are available in various thicknesses and widths and are long strips of material with a specified cross-section.
(vii) Sheet:
It is a very thin sheet.
(viii) Bar:
The bars are usually circular in cross-section and several meters long. They are common stock (raw material) for capstan and turret lathes.
(ix) Thread:
A wire is a length (usually coil-shaped) of a small round section; whose diameter specifies the size of the wire.
