Regardless of the type of machine being used, the instructions are typically provided in one of two ways, either; 1) via manual data input (MDI) using some kind of human interface built into the CNC machine, or 2) by producing a digital file using offline CAM (computer-aided manufacturing) software.
In recent years, there has been a substantial increase in part complexity. This, combined with an increasing pressure to improve part quality and increase overall operations effectiveness (OOE) has resulted in the most manufacturers moving away from manual (MDI) CNC programming and investing in CAM software.
CAM software, such as Autodesk Fusion 360, is used to create a digital file (NC program) that contains instructions necessary to control how the machine will function. The CAM software is used to define the entire machining process and often uses a digital twin of the machine, cutting tools, and work-holding that will be used. This "offline" programming allows the machining process to be developed away from the physical machine – meaning problems can be simulated and avoided long before they're run on the actual machine. The use of CAM software plays a major part in helping manufacturers to make better use of their CNC machinery, and to avoid costly machine down-time that would otherwise be caused by unnecessary data input.