CNC machining is a tried-and-tested manufacturing process for all kinds of metal parts across a range of industries. It’s also widely used for both production and prototyping, with machine shops around the world frequently taking orders for visual, mechanical and final-stage metal prototypes. Advantages of CNC machining include strong parts, scalability and tight tolerances, making the process preferable to additive in many situations.
Where are processes like Selective Laser Melting (SLM) build parts layer by layer from melted powder, CNC cuts material away from a chunk of extruded metal known as a “blank.” The extruded metal blank is physically consistent and requires no adhesion between layers. It is a solid block, and it can, therefore, be used to make strong, rugged prototypes with minimal deformities.
In general, CNC machining is far more accurate, which means metal prototypes can be machined with much tighter tolerances using a CNC machine. CNC tolerances can be as low as ±0.025 mm. Metal parts are also highly repeatable when made with a CNC machine. This is more important during production, but can also be advantageous when creating multiple prototypes for mechanical testing.
For anything more than a handful of units, CNC becomes cheaper and more efficient than the alternative. CNC machining may be much more economical in the long term. Because if the project needs to be scaled up and more units are required, it is easier and faster to increase the order size using CNC machining.
When creating metal prototypes, it is generally preferable to use CNC machining, since the process creates repeatable, precise parts with excellent mechanical properties. However, choosing the ideal process depends on your situation and specific requirements.