CNC machining is most suited for creating precise parts be it large or small components. They are routinely used in
• creating master patterns for molds
• Large sample parts before using in production to verify the fit and form
• Display models
• Inspection fixtures for assembly jigs
• Production components for low volume use
• Engineering models
• Injection mold creations
Aerospace applications witness widespread use. Testing parameters in aircraft design is very stringent in the sense that components cannot be allowed to fail when operational. Prototyping allows quick development and performance improvement on the fly meaning parts can be improved constantly. The advantage of the CNC applications is the G code language technology that can save existing parameters, which allow minute changes in the tool path altering the configuration of the component ever so slightly. Most satellites are prototyped as there is no possibility of large volume production of satellites. The example of Cassini and recently Juno which is orbiting the planet Jupiter are excellent examples. The Rosetta spacecraft is already on its way in a controlled descent to meet its end on the Comet 67P/Churyumov–Gerasimenko from orbit; this is another fine example of a prototype manufactured on a CNC machine. The Rosetta space craft has so many instruments onboard that space is perhaps the costliest in terms of real estate. Without CNC machining capability this mission by the ESA (European Space Agency) could not have created history and our knowledge of the cosmic origins would have remained static.
The best example of prototyping via CNC modeling is the latest iPhone 7 model. Countless software simulations were carried out to see how the removal of the headphone jack would make space more efficient. Once the software froze the design validating the design was turned over to 3D modeling. Technologies such as fused deposition in 3D systems simulated the iPhone 7 housing design. The next step of actually machining the housing from the material that would be used in volume production happened resulting in the iPhone7 still retaining the simplicity of design as envisaged by the late Steve Jobs with additional form and function. The net result of this prototyping has resulted in a larger battery and twin camera lenses which make the iPhone 7 perhaps the best camera phone just short of a top-of-the-line DSLR (digital single-lens reflex).
CNC machining for prototyping is preferred for the following attributes
• Speed
• Tolerance precision akin to large volume manufacturing
• Accuracy pertaining to original 3D design parameters
• Capability of machining wide variety of materials
• Concept stage to prototyping with fast turn-around times
• Simulation helps in pointing to problems in final part production
Types of materials used in prototyping via CNC Router machining
• ABS
• Polychromatic
• All type os plastics
• Polypropylene
• Acetyl
• HDPE
• PTFE
• Radel
• PVC
• Aluminum
• Brass
• Steel
• Titanium
• Brass
• Foams
• Modeling board
CNC machining allows precision parts prototyping that cannot be done by any other machine. The process also allows excellent finishing by removing machine marks, edge breaks and if required be ready for plating, priming or painting operations to obtain textures or high polish as required by the design.
