Forging is an important part of most of the manufacturing processes, especially those that involve metal molding.
In forging, metal is molded or re-shaped, no part is cut away. This involves rearranging the grain structure while keeping its consistency intact.
From Aerospace to Transportation, forging is used extensively. To better understand and implement forging in your manufacturing process, you must read this in-depth forging guide.
Why Forging is Beneficial in the Manufacturing Process
As a result of forging steel, you improve the grain structure by manipulating and kneading the steel a bit like rolling dough, consequently increasing steel’s quality. Forging effectively removes fine inclusions or impurities within the steel, such as gas pockets or even laminations.
The forging of shapes is another beneficial advantage. Due to this, forged products are more resilient, longer-lasting, safer, and more cost-effective.
Once the forged process is completed, it is important to carry out the correct heat treatment processes. When a forged product is complete, the steel is closest to a normalized state, meaning it is soft and can be bent easily. This is then followed by quenching the steel that causes a highly refined grain structure. Lastly, the steel is put through the tempering process that decreases the hardness of the alloys, which is usually accompanied by an increase in ductility.
Casting Vs. Forging: Which One is Better?
There is a lot of confusion regarding these two processes. In this section of the article, we will try to understand through facts which process stands out.
Cast parts are weaker because they have many voids in them. They have no grain structure & no organization. The grains are arranged haphazardly.
If you were to study the grain structure of a cast iron through a microscope, you would see that it’s very porous and it looks like a sponge.
Why does this happen?
Let’s imagine a perfect mold – one side is not cooling faster than the other side, and the & viscosity of the steel that’s being poured in here is perfect. Basically, we’re referring to a casting process at its highest possible quality. As the steel is cooling from the outside to the inside, things called dendrites will form, and they look like snowflakes. As they cool down, they’re going to form grains, but the grains won’t be in any order.
Remember, even if you have everything perfect, there will still be voids due to inconsistent grain structure. This is why casting doesn’t create a very strong product.
So, for metal parts that are under high stress, casting is not the best decision. This is where a billet comes into play.
Forging Through Billet
The process starts by putting the liquid steel into the billet. Instead of pouring liquid steel, it is cooled off & slid down a chute so that it is in the shape of a rectangular tube. As it goes down, the hot roll is going to squeeze that steel straight through. The grains get into a straight line, and the voids are eliminated.
The best part about forging is that the manufacturer can easily create the desired shape without forming any void due to the consistent grain structure. Forging can also be done through cold rolling, though that would increase the billet cost and require more expertise. However, the grain strength will increase, and the voids’ formation will be eliminated by 99%.
Forging vs. Casting: The Conclusion
If you’re creating low-stress materials like figurine, you can go with casting. The pricing will be cheaper, and you can be more detailed in the structuring part.
For materials with high-stress applications, forging is preferred.
Forging is a widely used metal molding process in various sectors like Aerospace, ball bearings, Car Parts, Industrial Machinery, etc. We hope this article on forging would have helped you understand it better.