A lot of people are wondering about the difference between cold forging and hot forging. Before you know the difference, you have to understand what forging is and what the process entails. Forging is simply a manufacturing process that shapes solid metal when compressive forces are applied.
There are several reasons why a manufacturer would choose a process. But one major difference between hot and cold forging is the temperature used. Let’s take a look at each of these processes and spot the differences.
Cold forging
As mentioned earlier, forging shapes a metal workpiece via compressive forces. The cold forging process is done at room temperature. The metal workpiece is compressed between two dies till the shape is attained. The techniques involved in this process include spinning, rolling, pressing, drawing, extruding, heading, etc.
One of the commonest manufacturing processes is cold forging extrusion. It is often used to produce automotive parts.
Why do manufacturers prefer cold forging?
A lot of manufacturers prefer cold forging over hot forging because parts produced from cold forging need little to no finishing. The bars are often annealed before being forged, so there is no need to treat them via secondary heat before machining.
Another advantage of cold forging is that it saves material. At the end of the process, the initial workpiece weight is the same as the forged material weight. These forged parts have accurate dimensions and premium surface quality.
Furthermore, cold forging has several economic advantages in terms of products and sales. It also has high production rates and long die life.
Does that mean that there are no disadvantages? Of course, there are.
The manufacturer can only shape products in high volumes. The level of deformation and shaping that can be carried out on that part is very limited. If they have a customer that is looking for a specific customized part, they can’t manufacture it through cold forging
Furthermore, cold forged parts are not very ductile, so you can’t use them for certain configurations. Also, residual stress can occur in these parts because of their grain structure.
Let’s take a look at hot forging
Hot forging
Just as the name implies, this process is done at extremely high temperatures. This temperature is important because it helps the part to avoid strain hardening during the deformation process. The high temperature also allows the highest level of material deformation and complicated 3D geometries.
One of the most popular hot forging processes is the stamping process. This involves squeezing the material in a press between a die surface and tool. Some manufacturers go for hot forging because it allows for more flexibility, as customized parts are easier to make with the process.
Are there disadvantages? Yes, there are. The properties of hot forged metals can be gotten by additional heat treatment which involves additional costs.
The difference between hot forging and cold forging
Cold forging manufacturing processes enhance metal strength via strain hardening, while hot forging manufacturing processes protect metals from strain hardening when subjected to high temperatures.
