When product designers need to make metal parts, they will find a variety of manufacturing methods to choose from. Among them, the two most popular options are casting and machining. But how do they compare? This article provides an overview of these two valuable metal manufacturing processes, and you will learn how casting and machining compare and which process is likely to be the best for your manufacturing application.
What is casting?
Metal casting is a manufacturing technique in which molten metal is poured into a mold (sometimes called a die) where it is cooled until fully solidified. The solid metal parts are then removed from the mold. In most cases, secondary finishing processes are used to further refine cast metal parts into finished products.
Depending on the material chosen, the size of the casting, the shape of the casting, and various other characteristics, many different metal casting techniques can be used. Some of the most popular casting methods include die casting, sand casting, pressure casting, and investment casting.
CNC machining is a reduction manufacturing process in which a milling machine, lathe, or other processing equipment is input into a computer program that controls its operating parameters to selectively remove materials from base metal stocks. After zeroing relative to the part to determine the origin, the CNC machine gradually removes a small amount of metal until the final shape is reached.
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 usually utilize a variety of equipment so that they can use the best tools to get the job done. If this is the most efficient process, it is not uncommon for parts to move between multiple equipment stations.
Casting and Machining: Choose the best method
When comparing casting with CNC machining, both are very valuable metal manufacturing methods. This means that choosing the right method depends on your project constraints and final part requirements. In general:
CNC machining is the preferred method for prototyping unique parts or quickly producing small and medium-volume products. When you have very strict tolerance requirements for part accuracy and surface finish, choose machining.
Metal casting is the preferred method for producing large quantities of identical products. It can also be used to produce complex internal cavities that are difficult or impossible to recreate using other methods.
In some cases, a combination of casting and precision CNC machining may be the most efficient and reliable method for producing parts. When you produce parts by this method, they are called machined castings.
