Staffing
RP: Minimal
With the exception of secondary operations (benching), RP requires little labor. Within a few minutes, it is possible to prepare files for part production and start the build. During the build, there is little or no operator attendance.

CNC: Significant
CAM software applications have improved, but in most cases, they have not eliminated the need for human intervention. Machine setup and operation require an experienced machinist and it is rare that prototypes are made in a lights-out mode.
Skilled Labor

RP: Minimal
The technology is certainly not a minimum-wage position, but when compared to machining, the demand for highly skilled talent is much less. This is true in part because less labor is required. Additionally, RP has improved in ways that take the art out of the process.

CNC: Moderate to high
Machining takes skill, creativity and problem-solving abilities. From designing toolpaths and machining strategies to operating and monitoring the cutting, machining is the work of experienced craftsmen. With organizations getting leaner and the availability of machinists declining, there could be a lack of available resources for prototyping work.

Leadtime
RP: Short to moderate
With less labor, fewer steps and an insensitivity to design complexity, RP reduces leadtimes not only for the physical build, but also for the entire process. Overall, the RP process is more efficient in both time and labor. With RP, data can be received at 4:30 p.m. and parts delivered the next morning; this is unthinkable for CNC machining unless there is more than one shift. Yet, this does not mean that RP is the fastest for all parts.

CNC: Moderate
A lot goes into machining. Labor, toolpaths, fixturing, machine time and materials are required. The result is that many jobs will take longer than those done in RP. However, CNC can be faster when the design is simple and straightforward, and when high spindle speeds and feedrates are an option.

Practically speaking, the selection of the best technology may come down to machine time availability. Often, a looming deadline will override any accuracy or material property requirements. This, in turn, reveals the true measure of what is important to the prototyping application.

So, what is important to that next prototype – time, quality or cost? Balancing these factors requires a thorough knowledge of both RP and CNC. With it, informed decisions – not biased opinions – can be made for the selection of the best technology for the application.