CNC Machining for Rapid Prototyping

CNC Machining

CNC Machining and Rapid Prototyping

Prototyping, also known as prototype manufacturing, is the process where a manufacturer creates a small batch of products from digital design drawings. Manufacturers can use these functional prototypes to find flaws in the design and fix them before producing large numbers of parts. Companies can also use prototypes to participate in exhibitions and do market testing.

Traditionally, prototypes are mainly created by hand, which is time-consuming and labour-intensive. Currently, the development of CNC machining has allowed engineers to produce prototypes more quickly and inexpensively than ever before.

CNC machining uses computer control equipment like drills and lathes, so it’s fast, precise, versatile and consistent. In addition, it can process a wide range of compatible metal and plastic materials. It is used across almost all industries for various prototype and end-use parts.

Contact RpProto to get quick quotes for CNC machining prototyping.

CNC Machining Suitable for Prototyping?

Compared to other methods, CNC prototype machining is an excellent option since it can produce small quantities of a prototype quickly. In addition, it can process almost all solid metals and plastics, such as the most commonly used aluminum alloys, stainless steel, ABS, etc. CNC machining can be an ideal solution for product developers who need small volumes of high-quality appearance or functional prototypes.

CNC prototyping machining can make all kinds of prototypes easily. For instance, presentation prototypes might visually represent the product’s appearance or functionality. On the other hand, functional prototypes need tight tolerance and focus on the product structure. CNC machining is always the best option for these functional prototypes that require tight tolerance, mechanical structure, or other characteristics that additive techniques cannot provide.

Advantages of CNC Machined Prototypes

CNC Machining is Rapid

CNC machining with a sophisticated computer system can build final parts from the design idea quickly. In addition, CNC prototype machining does not require any mold or time-consuming preparations. Its ability to modify design files also gives the machining centers the option to make adjustments to the prototype in time. It is a fast procedure suited for short lead times and delivering items to market as soon as possible.

CNC Machining Needs No Tooling

Unlike pressure die casting or plastic injection molding, CNC machining does not require separate tools and molds. This effectively reduces the cost of product development and shortens the time to launch new products to the market.

It takes a few months to make and test the injection and die-casting mold. In comparison, vacuum casting uses silicone molds, which also take days to complete. This is worthwhile for many tasks, particularly when duplicating fine surface textures reproduced from a master design. However, CNC machining does not need these preparations.

CNC Machining is Easy to Adjust

With CNC prototype machining, the manufacturer saves money in the long run. This is because the defects and errors can be rectified in the small prototype batch instead of carrying out the defect in large quantities of the final part in the production stage.
Improvements and modifications to the original design are easy with CNC machining, where altering digital instructions is simple and only takes a few minutes. Additionally, future changes require minor modifications to the CAD designs instead of creating a new design from scratch.

Structural Integrity

CNC machined prototypes offer superior structural integrity than 3D-printed items. The material’s strength, stiffness, and hardness might be referred to as structural integrity. These properties are crucial.

Geometric discontinuity is less likely to occur since CNC machining is cut from solid, consistent material stock. In contrast, 3D printing may result in voids, porosity, or layer shifting. Therefore 3D printed parts can adversely affect the structural integrity of the finished product.

High Precision

Compared to other rapid prototyping techniques, CNC machining is one of the most reliable manufacturing processes for parts with tight tolerances, whether the prototype is made of plastic or metal.

Computer-controlled machine tools using modern cutters are accurate and precise, reliably making parts tolerances of+.05 mm or better. Therefore, CNC machining can efficiently and accurately make parts with complex geometries. Additionally, this is a repeatable tolerance, easily achieved over unlimited part numbers production runs.

It is precise enough for the great majority of prototypes and commercial applications.

Material Selection

CNC machining is so versatile. It can be performed on virtually all solid materials ranging from metal alloys to wood to plastic. You can machine vinyl, fibreglass and carbon fiber materials, laminates, fibreboard, and corrugated plastic!

Metal materials commonly used in CNC machining are Aluminum, Steel, Stainless Steel, Magnesium, Titanium, Zinc, Brass, Bronze, and Copper.

Commonly used plastic materials for CNC machining are ABS, PC, PP, PS, POM, PMMA, PAGF30, PCGF30, Teflon, LDPE, and HDPE.

Prototype CNC machining is an ideal process for mid-stage functional prototypes. RpProto 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″

Disadvantage of CNC Machining

cnc machine

When deciding between CNC machining and alternative prototype techniques, you should consider following limitations.

  • Compared to 3D printing, CNC prototype machining is more expensive since producers have to pay more for materials. CNC machining is a subtractive process. It produces the final product by removing material from a larger beginning block. So more material may be used as a result than with 3D printing. However, it is important to note that the higher cost comes with added precision and the ability to work on a wider range of materials.
  • Processing intricate interior geometries, like internal cavity hollows, using CNC machining is challenging. Certain geometries cannot be produced with CNC prototype machining because it operates from the outside to the inside. In contrast,  3D printing makes interior geometries more effective since it manufactures objects from the inside to the outside.

Applications of CNC Machined Prototypes

CNC prototype machining is used in practically every industry. Most of these sectors require a functional or appearance prototype to demonstrate how the actual product operates. Machined tooling is generally prefered for these functional prototypes that require strength, mechanical stability, or other features that additive techniques cannot provide.

Medical Industry

Medical device firms must create a prototype while creating new medical equipment because it helps them know that the product will perform the desired function. All of these medical devices need precision and strong materials. Because alternative technologies lack the requisite precision, the CNC machining process will produce the highest quality working prototypes for such equipment. CNC prototyping is most suitable for making this equipment. Examples include orthotic devices, safe enclosures, implants, MRI machines, research equipment, and other similar items.

Automotive Industry

CNC machining is widely used to develop automotive prototypes, such as bumpers, headlights, and dashboards. Automotive companies develop and test these prototypes to see if they’ll function and fit well into the car before mass production.

Aerospace Industry

The aerospace industry needs prototypes that help test the part’s functionality before it is used in an actual aircraft. The CNC prototype machining process is responsible for making many components in this industry, such as landing gear ports, bushings, manifolds, airfoils, etc. CNC machining is used in the aerospace industry.


Prototypes are used in the production process to avoid design issues, and CNC-machined prototypes are an excellent technique in the prototype stage. It uses a rapid procedure and has shorter cycle times. Also, it has some similarities to the final product compared to methods.

CNC Machining Prototyping with RpProto

RpProto provides our customers with high-quality, precision prototypes for various industries. We inspect all CNC-machined parts with CMM or laser scanners. Don’t hesitate to contact RpProto to get CNC-machined prototypes when you need prototypes. Let’s find out if CNC machining prototyping is the right option for your project.

Regardless of the type of CNC services you need, RpProto makes it faster, easier, and more efficient to source and supply quality mechanical parts. Head to and upload your designs to get an instant quote today!


When you need to manufacture tight tolerant, sturdy prototypes rapidly with various materials, CNC prototype machining is one of the best options.

CNC machine prototypes are relatively cheaper as you do not have to spend any cost on making the mold.

The cost of a CNC prototype depends on the requirements of the prototypes, like the complexity of geometry, materials, finishing, etc. Some prototypes can be made by 3-axis machines which are relatively cheaper. In contrast, some of the prototypes can only be made by 5-axis machines, which could be expensive.

Scroll to Top