Question

Steel Structures

The rolling process is one of the most frequently used forming processes for producing steel sections. Nonetheless, other forming and fabrication processes can be used to create a range of section shapes in the steel production process. For this assignment, you are required to review the other four types of steel forming/fabricating processes including drawing (manufacturing), extrusion, casting and forging.

Task 1(IN YOUR WORDS) : answer in 250 words)

Review the drawing (manufacturing) process and mention the type of section(s) produced from this process. You should also mention the limitation(s) of this process.

Answer 1

Steel Forming Processes:-

1.Drawing:-It is a metal working process which uses tensile forces to pull or stretch the material either metals,plastics etc. The material is pulled and transformed into a desired shape and thickness. It is further classified into several types: sheet metal drawing, wire drawing, bar drawing and tube drawing.For wire, bar, and tube drawing, the raw material is drawn through a die to reduce its diameter and increase its length. It is usually called cold working process because of its working temperature i.e room temperature,however it is sometimes performed at elevated temperatures to reduce forces.The raw material of cold drawing is hot-rolled stock of a suitable size.

2.Extrusion :- It is a metal forming process in which the work piece is forced to pass through a die to reduce its cross section or convert it into desire shape.Different types of extrusion are Direct Extrusion,Indirect Extrusion,Hot Extrusion & Cold Extrusion.This process is similar to drawing with difference as it uses compressive forces to push the material through the die.The compressive force allows large deformation compare to drawing in single pass and it is most commonly used to extruded plastic and aluminum.

3.Casting:- It is a manufacturing process in which the material in liquid form is poured into the mold made up of clay and sand which contains a hollow cavity of the desired shape and then the liquid is allowed to solidify.This solid part is also known as a casting which is ejected out of the mold to complete the process.Different types of castings are Centrifugal casting ,Die casting,Molding,Sand casting.The materials are usually metals or epoxy, concrete, plaster etc.This manufacturing process is mostly used for making complex shapes which are difficult or uneconomical to make by other methods.

4.Forging :- It is a manufacturing process in which the shaping of metal is done using localized compressive forces.The blows are delivered with a power hammer or a die.Different types of forging are cold forging,warm forging or hot forging.Forged parts can be of weight from less than a kilogram to hundreds of metric tons.It has been done form past many centuries ,the traditional products were kitchenware, hardware, hand tools, edged weapons, cymbals, and jewellery & now it is used in mechanisms and machines wherever a component requires high strength.

***The sections which can be produced from drawig process are:-

1.Sheets

2. Bars

3. Rods

4. Tubes

5. Square hexagonal

etc. and many other profiles can be drawn from this process.

Limitations of Drawing Process :-

1. Only a constant cross section products can be made through this process.

2. Lubrication is necessary.

3. Close tolerance can't be achieved.

4. No refined grain structure .

5. Material homogenity is poor.

6. It is a discontinuous process.

7. Lower production rate.