Die casting or CNC machining? from luis huang's blog

Two of the most popular industrial processes for creating metal parts are die casting and CNC machining. Both processes can even be combined for the best possible finish. However, when it comes to choosing one process over the other, there are several important factors to consider. Read on to find out when you should use die casting and when you should use CNC machining.

What is the difference between die casting and CNC machining?

Die casting involves melting metal and injecting it into a steel mould (the die). The metal is then cooled down so that it hardens in the shape of the part. CNC machining, or Computer Numerical Control machining, automates the process by using a robot to sculpt the part from the metal. Both of these processes are frequently used to manufacture metal components and fittings for objects that we use every day – such as car and computer parts.

Should you choose die casting or CNC machining?

CNC machining tends to be more expensive than die casting, but this depends on the type of parts and level of production. Often, CNC machining is used to create the die, and/or to add more intricate features after a part has been die cast.

If you want to compare the separate processes for forming a part, here are several of the major deciding factors:

Volume

If you are only producing a low volume of parts, CNC machining has the advantage because it doesn’t require tooling costs. On the other hand, when it comes to high volume production, die casting is the better choice for consistent quality and quantity. Die casting is best for durable mass production, while CNC machining is best for small runs of particularly complex or oddly shaped parts.

Speed

Die casting is much faster than CNC machining and easily repeatable. Even if machining is required post-casting, it will still take far less time than machining a detailed part from a solid block of metal. This speedier production cycle makes die casting more reliable for producing large batches. That said, CNC machining can create a faster lead time when it comes to producing smaller volumes, as long as you have the digital model ready. It can also be faster when testing prototypes.

Precision

Die casting can precisely form complicated geometrical shapes, but can sometimes result in surface defects such as burrs or flashes which require machining to clean up. CNC machining can create finished parts with great precision and tolerance, especially if they are highly customised small parts. However, die casting is still a great choice for creating identical parts when the surface detail can be engraved into the master mould.

Waste

There is very little scrap metal left after die casting, which makes it more affordable. CNC machining can leave a lot more scrap behind when carving away layers of a metal block. If you are concerned about minimising waste, but would prefer to use CNC machining, it is important for a recycling system to be in place in order to reuse the scrap metal.

Maximising your returns

It is sensible to be cautious about initial investment in a project, especially if there is a strict budget. If you are unsure which is the optimal method for you, it is best to discuss this with experts. Lupton & Place are leaders in die casting throughout Europe, and also offer in-house CNC machining.