Time to read: 5 min

In simple terms, prototyping is the process of physically building a model or draft of an idea. As engineers, prototyping is a crucial step in the product development process whereby a solid model comes to life and we can touch, see and interact with it. Historically, prototyping has been a lengthy and expensive process, but modern, rapid prototyping allows ideas to take shape in a matter of days. 

CNC machining is excellent for large, aerospace prototype parts

Traditional vs Rapid Prototyping

Traditionally, prototyping for product development has involved the following steps: 

  1. Spending days or weeks designing a product with solid modeling software to create a 3D CAD model and a set of 2D drawings.
  2. Get quotes to fabricate the necessary components from several manufacturers 
  3. Wait weeks or months to receive your machined prototype, usually without much communication

This old style prototyping relied upon sand casting and mock-ups using clay molding, wood, wire and tape. Although claymation movies may be amazing, those antiquated methods are best left to filmmakers. With the invention of CNC machining, 3D printing and rapid prototyping methodology, today’s engineers can fabricate prototypes far faster than ever before.

rapid prototyping utilizing 3D printing additive manufacturing is beneficial in many instances

Rapid prototyping utilizes many processes, including: 

One concern with rapid prototyping is that 3D printing creates something that looks like the 3D model, and may even be able to move or function as intended, but is dimensionally inaccurate. That’s why 3D printing is an excellent and cost-effectiv option when you’re looking for a prototype for display purposes only.

Rapid prototyping with 3D printing also yields parts that are a different density with different material properties than the final product. This is due to the narrow range of available materials for 3D printing — though the number of materials that can be utilized in additive manufacturing is continuously growing. For instance, metal 3D printed parts are often more porous, which can cause mechanical failures and variable density if not subsequently processed. 

CNC rapid prototype machining is the optimal choice when you need an engineering prototype or production prototype that looks, feels and functions as the finished product. And, with digital manufacturing infrastructure, like Fictiv’s platform, you can get instant quotes for CNC machined prototypes with turnaround times as little as a few days.

Benefits of CNC Machined Prototypes

Structural Integrity

CNC machined components offer a higher degree of strength and similarity to desired finished product mechanical and material properties than 3D printed parts. Among these desired properties, structural integrity is arguably the most important — structural integrity in this case can be defined as the material’s strength, stiffness and hardness. 

With additive manufacturing methods, layer fusion is not always 100% successful, which results in voids, porosity or layer shifting. These inconsistencies in the resulting part can have adverse consequences on the structural integrity of the finished product. With subtractive manufacturing (CNC machining), your prototype is carved from solid, homogenous material stock, which reduces the possibility of geometric discontinuity. 

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CNC machining is one of the most reliable manufacturing methods for parts with tight tolerances. CNC machining can maintain tolerances as tight as one ten thousandth of an inch, whereas 3D printing can only hold a few thousandths of an inch (about an order of magnitude of difference).  

Dimensional Accuracy

Regardless of whether you’re CNC machining a prototype out of plastic or metal, you get a higher level of dimensional accuracy with CNC machining over other rapid prototyping methods. CNC machining can easily produce parts with complex geometries at a high level of accuracy.

fast CNC prototype machining results in high-quality parts with excellent accuracy

Material Selection

Simply put, CNC machining can be performed on a variety of materials ranging from soft and ductile to hard and rigid, and from metal alloys to wood to plastic. CNC machining is so versatile, in part, because it is a solid manufacturing method that can be utilized with virtually all solid materials. You can even machine vinyl, fibreglass and carbon fiber materials, laminates, fibreboard, and corrugated plastic! 

Product Size

Take a look at this massive CNC machine touted as the largest in the world. It’s capable of producing parts that are up to eight feet tall! The Thermwood M400 weighs an impressive 51 tons and has a head that can generate speeds of up to 20k RPM. While this particular CNC machine isn’t available for purchase, it shows just how big of a part you can manufacture with CNC machining. For prototyping, that capability can be an important feature if you need to avoid extensive assembly steps to get a prototype. 

Of course, there’s the the self-proclaimed world’s largest 3D printer — a University of Maine’s Advanced Structures and Composites Center creation — that has a 100 foot bed. Still, large part production is optimal with CNC machining. 

Prototype CNC machining is an ideal process for mid-stage functional prototypes. Fictiv can help you accelerate development cycles with rapid prototyping by providing instant online quotes, intelligent DFM feedback, and quick lead times.

  • Finishing, masking & hardware installation
  • CNC Milling, CNC turning, gear hobbing, EDM
  • Tolerances as tight as +/- 0.0002″

Considerations for CNC Machined Prototypes

The following are key limitations to consider when choosing between CNC machining and other methods for prototyping: 

  • Other rapid prototyping methods may result in shorter turnaround times (Note: This is unique to prototyping runs as larger volume production lead times are typically shorter with CNC machining)
  • With additive manufacturing, you can create lightweight prototypes for display purposes because you can leave the internal cavity hollow. Achieving the same with CNC machining is much more complex. 
  • As far as material waste is concerned, additive manufacturing is a more sustainable choice, due to the layer building nature of additive manufacturing (Though you can often recycle the chips that result from CNC machining). 

CNC Machining Prototyping with Fictiv

Fictiv has a proven track record for providing our customers with high quality, precision prototypes for a variety of industries. Check out what our customer, Honeywell, has to say about their experience working with Fictiv for product development. 

Additionally, here are some of the benefits we offer customers to ensure a successful CNC machining prototype result: 

Regardless of the type of CNC services you need, Fictiv makes it faster, easier, and more efficient to source and supply quality mechanical parts. Head to Fictiv.com to learn more about our CNC Machining Service, then create an account and upload your designs to get an instant quote and free DFM feedback today!