cold drawn steel bars

How Cold Drawn Steel Bars are made?

Steel rods involve multiple steps of manufacturing, from converting the raw steel to the finished products. One of the processes is called Cold Drawing Process, widely used in the steel industry for stretching the metal at room temperature. Amongst the other cold finished steel bars, these cold drawn bars are majorly used in the steel industry. These bars are versatile in nature, they are used in high volume productions. 

Cold Drawn Process

The cold drawing process is one of the most common methods used by the steel manufacturing industry. This process involves multiple drawings from the single wire to obtain top-notch ultrafine fibers. In short, this is a method of pulling a hot steel bar via a die that is much smaller in size. There are various other methods involved in this; we are going to list down all of them for detailed knowledge about cold drawn steel. 

Cold drawn steel bars

a) Shot Blasting

The initial part of the process, where the material is cleaned to ensure there is no rust or dust left on the surface. This procedure helps to ensure a neat and smooth surface to carry the drawing lubricant into the die. 

b) Coating

The next step after cleaning the metal is to coat it for further steps. The metal is coated with lubricants to ensure there is no hurdle in the drawing procedure. 

c) Cold Drawing

The prime process of obtaining the ultrafine fibers from the cross-sectional shape is called cold drawing. A heavyweight drawn bench is used for the formation of heavy steel bars. The robustness of the die ensures that there’s no disturbance caused by moving due to the operation. A pusher mechanism is incorporated to grab the bar through the die. 

If we consider the outcomes, the productivity is low, and the cost of the die is high. To reduce the production cost, we can switch to cluster drawing. This process helps to draw a lot of wires at one single time that increases productivity. 

d) Extrusion

Extrusion is a process that involves the force through a bell other than the end of the die. This process is incorporated majorly with large diameters and shorter lengths. Extrusion produces better results as compared to cold drawing in terms of the outer diameter of the material. This method involves the elongation of the wire. Typically this is used for bars, wires, rods, and tubes. Tube production via this process requires more additional tools like non-deformable & deformable mandrels. Once extrusion is over, annealing starts, lubricants are required throughout the whole process for a smooth finish.  

e) Annealing

The process of softening the material being drawn is known as annealing. Majorly this is used to modify the microstructure, mechanical properties, and characteristics of the steel bars. It is a heat treatment, used to increase the ductility and reduce the hardness of the metal. 

The atoms migrate during the heat process in the form of a lattice; it changes the ductility and hardness of the material. This process is essential to reverse the hardening effect. If the material is hard, it might break product due to cracking.

After the annealing process, wires are straightened and cut after they have achieved the desired diameter. This is a widely used method by steel fabricators for complex designs and better quality outputs. 

f) Straightening 

Once the drawing process is over, the bars undergo a straightening process. There are various tolerances in straightening that depend upon the grade and sizes of the material. This process is beneficial for the smooth surface; it also works to modify the size slightly. 

g) Saw Cutting

The second last step is where steel bars are cut according to the required size. This process is done with the help of the end gripper that marks the bars from the left and cuts them into various sizes as per the market standards. 

h) Packaging

The final stage is packing; the bars are packed in huge amounts as per the requirements. Before these bars are out of the manufacturing unit, there is a final step of result preventive coating which enhances the life & the quality of the product. 

Benefits of Cold Drawn Steel Bars

There are numerous benefits of using cold-drawn steel bars; the prime is that they offer tighter tolerances and section properties. These bars have improved straightness and a better surface finish. The surface is exceptionally smooth and the difference between hot rolled bars and cold rolled bars can be easily depicted from its appearance. Another great benefit of these bars is that they have better mechanical properties and higher tensile strength. These bars are more robust than the hot-rolled bars due to which this process is highly used in the industry. The benefits aren’t over yet; these bars are economically more feasible because of less mechanism, less scrap, and better surface finish. 

Industrial Use of Cold Drawn Steel Bars

Many industries like- automotive, power, aerospace, fluid engineering, and water treatment are using this method. The cold-formed steel bars are utilized for dental, nautical, and medical tools. These bars are widely used because of their properties and high surface finish. The high tolerance offered by these bars makes them perfect for industrial use. 

Conclusion

To meet the increasing demands of the industry, we need to move with the new technology to increase productivity. Incorporating these modern methods help to make production more economically feasible by reducing wastage. The steel industry is continuously evolving by using these methods for higher production. 

Read here, How steel is the most eco friendly material.

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