Detailed Introduction to Casting and Machining

When product designers need to manufacture metal parts, they will find that there are various manufacturing methods available. Among them, the two most popular options are casting and machining. But how do they compare? This article outlines these two valuable metal manufacturing processes, and you will learn about the comparison between casting and machining, as well as which process may be the most suitable for your manufacturing application.

What is casting?

Metal casting is a manufacturing technique that involves pouring molten metal into a mold (sometimes referred to as a die) and allowing it to cool until it solidifies completely. The solid metal part is then removed from the mold. In most cases, secondary finishing processes are used to further refine the cast metal parts into finished products.

Depending on the chosen material, the size of the casting, the shape of the casting, and various other characteristics, many different metal casting techniques can be employed. Some of the most popular casting methods include die casting, sand casting, pressure casting, and investment casting.

CNC machining is a subtractive manufacturing process in which milling machines, lathes, or other machining equipment input computer programs to control their operational parameters, selectively removing material from a stock of base metal. After zeroing the part to determine the origin, the CNC machine gradually removes small amounts of metal until the final shape is achieved.

CNC machining can refer to several different types of machining. This includes traditional machining processes such as CNC turning, milling, drilling, boring, and sawing, as well as modern unconventional machining processes such as laser cutting, wire cutting, and abrasive water jet cutting.

Machine shops typically utilize various equipment so that they can use the best tools to complete the work. If this is the most efficient process, it is not uncommon for parts to move between multiple equipment stations.

Casting and Machining: Choosing the Best Method

When comparing casting and CNC machining, both are highly valuable metal manufacturing methods. This means that the correct method depends on your project constraints and the requirements of the final parts. Generally:

CNC machining is the preferred method for creating unique part prototypes or for the rapid production of small to medium-sized batches. Choose machining when you have very strict tolerance requirements for part accuracy and surface finish.

Metal casting is the preferred method for producing large quantities of the same product. It can also be used to create complex internal cavities that are difficult or impossible to reproduce using other methods.

In certain cases, a combination of casting and precision CNC machining may be the most efficient and reliable way to produce parts. When parts are produced using this method, they are referred to as machined castings.