Forging vs CNC Machining: which one should you choose?

CNC machining undertaken by our team at Challenge Engineering

 

There are some things you need to get right when deciding how to get metal parts manufactured. How should they be made? Do you go for cast, forged or machined parts?

 

If you’re not sure, we’re going to explain and compare two specific ways of making metal parts, forging and CNC machining.

 

Hopefully, by the end of it you should be able to decide which is going to work best for your situation and specific requirements.

 

What are the differences between Forging and CNC Machining?
 

Let’s start by looking at each process.
 

Forging metal involves using a mould made from very tough steel. The mould comprises of two parts; the ‘tool’ which is the movable part, and the ‘die’ which is the stationary part. A press that exerts tons of force pushes the two halves of the mould onto a sheet of metal, creating the desired shape. The process can be done hot or cold, depending on the metal being forged. The part normally needs a little finishing, and that’s it.
 

CNC (Computer Numeric Control) machining, involves passing a lump of metal (or a billet as it’s known in the trade) into a machine tool. The machine has sensors built in to position and guide the billet. It is fully motorised and is controlled by a computer panel. A rotating tool cuts away unwanted metal to form the part. The computer interpolates the design to give smooth curves and circles.
 

What are the pros and cons of forging?
 

Advantages
 

If you are making tens of thousands of replicas of the same shaped piece of metal, simple nails for example, then forging is ideal as you create a single tool and die and off you go.

Forging changes the microstructure of the metal considerably, creating a finer grain and improving the fatigue resistance.
 

One way to think of it is that forging compresses the metal into having a similar structure to wood, so the resulting part is very str