CNC Prototyping
Getting a product from the blueprints to the visual stage is a key part of the product design process. It makes it possible for the design to be tested and validated before it goes into mass production. In this article, we are going to talk about one of the processes commonly employed in bringing those designs to life.

The process we are going to talk about is called CNC Rapid Prototyping. We are going to take you through five important things you need to know before you use this method. So, if you’re looking for information about a prototyping method for your project, keep reading.

What Is CNC Prototyping?

CNC prototyping is a combination of two commonly used words in the industry, CNC Machining, and Rapid Prototyping. To understand what it is all about, we need to define these two terms separately. Let’s look at their definitions.

Rapid Prototyping Definition

Rapid prototyping is the process of creating a scalable, pre-production model of a part or parts assembly from a 3D model or a CAD file. It refers to the fabrication methods or techniques used in creating the model. Rapid prototyping is done to either provide a visual representation of the design, or a functional prototype to test out the features of the design.

There are many methods used for rapid prototyping, among them are 3D printing(additive manufacturing) and CNC machining. Today we are going to be focusing on CNC machining. So, what is CNC machining?

CNC Machining Definition

CNC machining is the process of using a set of instructions from the computer to control and guide the movement of the cutting or machining tool. CNC machining is an umbrella term comprising different types of machines. We can have CNC lathe machines, CNC metal bending machines, and CNC milling machines.

The CNC machining process starts when the computer converts the CAD file containing the design or the 3Dmodel into a file called the GCODE. The GCODE is then transmitted to the machine where it is used to program and control the motion of the cutting tool.

Definition Of CNC Prototyping

Now that we have defined both terms, we can reasonably define what CNC rapid prototyping is.
This is the process of fabricating or creating a part of a part assembly from a CAD or 3D model using a computer-controlled cutting tool. Simple enough.

What Can You Do With CNC Prototyping Services?

CNC prototyping revolutionized the way products used to be designed when they first came out. It has shortened the design cycle considerably and given life to a new form of low volume, high-quality production. A new user might ask some questions about what can be done with CNC machining or how broad its range is. Let’s answer some of those questions.

1. What Materials Can You Create With?

You can create with almost all materials when using CNC machining. As long as the materials can withstand the stress and heat of the process, they can be machined.

Popular materials used are metals like aluminum, titanium, and steel. Plastics like ABS and polypropylene can also be machined. Even unlikely materials like wood and foam can also be machined to create your prototype.

2. What Machining Methods Can You Create With?

CNC prototyping makes use of many different types of machining processes like milling, turning, and even laser cutting. Like we mentioned before, CNC machining is an umbrella term for various computer-controlled machining and cutting processes.

Different machining processes can be used per the desired part geometry. We’ll talk more about that in a later section.

3. What Can You Create?

This process is primarily used for creating high-quality prototypes for functional testing.

It can also be used to create molds or casts for creating prototypes using other production processes like injection molding. This process is known as Rapid Tooling.

Why Should You Choose CNC Prototyping?

Two main options exist for creating prototypes from 3 models in the industry- 3d printing and CNC prototyping. Although 3D printing is steadily emerging as the preferred variant, CNC prototyping is still steadily holding down its share of the market. Let’s take a look at some of the reasons why it is still preferred over 3D printing:

1. CNC Machining Is fast

CNC prototyping is a fast method for making prototypes. Working with little human supervision, CNC machines can bring 3D models to life in a matter of hours. The short lead times help get the final products into the hands of the user faster than other prototyping methods.

2. CNC Prototyping Is Accurate

Accuracy is an area where this process beats out other prototyping means by a wide margin. It can be used to make parts with an incredible accuracy of up to 50 Microns tolerances. The surface finish can be improved by using advanced finishing methods. This makes it perfect for making parts for scientific and engineering use that require tight tolerances.

3. It Works With Many Of Materials

CNC prototyping can be used with a wide range of materials. Most prototyping methods like 3D printing are limited to a select range of materials due to their technology. With this manufacturing method, you can create prototypes with the same material you intend to use for your final product with ease.

4. CNC Machining is Easy To Modify

In the product development process, corrections sometimes need to be made to the design after flaws are observed. With CNC prototyping, it’s very easy to do this. All it takes is just to correct the initial CAD design and reprogram the machine. This speeds up the design time and gets the product to market faster.

5. CNC Machining Requires No Fixed Tooling

Most prototyping process often requires specialized tools that have to be prepared in advance eg. Hardened dies for injection molding. This can add to the cost of production and increases the lead time. None of that is needed in CNC prototyping. In this method, a wide variety of tools are available in the turntable. These tools can be cycled through or swapped out as needed to perform the job.

6. Quality And Consistency

Since it’s computer-controlled, CNC machines can reproduce the same part many times without significant deviation in quality. Successive batches come out of the CNC machines with very tiny dimensional variations. This particularly makes it useful for the production of assemblies where tight tolerances are required between mating parts.

7. Similarity To Final Part

With CNC machining, you can create functional prototypes. Rapid prototyping methods like 3D printing sometimes can only create visual prototypes. The prototypes they make cannot withstand the stresses encountered by the part during service. But with CNC prototyping, you can create prototypes that look, feel, and perform like the real thing.

Why Shouldn’t You Choose CNC Prototyping?

We’ve seen many reasons above why CNC machining would be the right option for creating prototypes. But, there are still some limitations that can make this process unsuitable for some projects. Let’s go through some of them.

1. Cost

Creating prototypes with CNC machining is expensive compared to using alternative methods like 3D printing. The cost of running the large CNC machines coupled with the additional skilled labor they required makes them more expensive. Even the raw materials used, like metals, are far more costly than their 3D counterparts.

This is why engineers and product designers should conduct appropriate cost studies before choosing a rapid prototyping method.

2. Waste

CNC prototyping is a subtractive manufacturing method. This means that creating the prototype involves gradually removing the excess material from a block until the final product emerges. Naturally, this creates a lot of waste which, apart from being environmentally undesirable, also increases the cost of the manufacturing process. Recycling is a solution used by some machine shops to recoup some of the lost material’s gain.

3. Geometrical Restrictions

Modern CNC machines like 5-axis milling machines are so advanced that they can cut or shape complex parts with ease. But, there are still some types of designs that these machines would struggle with significantly. An example of a problematic prototype is that with complex internal geometries. It can just be impossible to get the cutting tool in there in those cases. In cases like this, other prototyping methods are more suitable.

Three Things to Consider When Choosing the Right Machining Methods for Your Prototype

How To Choose The Best CNC Machining Process For Your Prototype

A lot of things go into choosing the right machining process for your project. Like we mentioned earlier, CNC machining is an umbrella term for the different machining processes that go into creating your prototype. To fabricate your prototype, you’ll have to choose one of these processes. We have put together some factors for you to consider when selecting a machining process.

1. Material

The type of material can determine the sort of machining process to be employed. For example, cutting sheet metal can require a CNC laser cutter or a water jet cutter, while creating 3D parts might need a milling machine. It is important to understand each material and its strengths and limitations.

2. Part Geometry

The geometry or the final shape of the part can determine the sort of prototyping method used. CNC machines like lathes create parts with circular cross-sections, drills bore precise holes in the workpiece, while CNC lasers and mills create 3D surface designs. Study the product’s design and choose the best method accordingly.

3. Intended Use

What the part needs to be used for also plays a huge role in selecting the CNC prototyping method. If the part is going to be used in an application that requires little in the way of tolerance then it doesn’t make sense to use an expensive method like laser cutting. If the part created is going to be used for a visual presentation,  it is advisable to save money and go for a less expensive prototyping method.

How To Find A Reliable CNC Machine Shop For Your Prototype

How To Find A Reliable CNC Machine Shop For Your Prototype

After deciding to go with CNC Prototyping for your project, the next step is to choose the appropriate service to create your design. Choosing a good machine shop can influence the success of the project to a great extent. When selecting a CNC machine shop, here are some things to look out for:

1. Top-class Equipment

Choosing a CNC machine shop with top-class equipment is very important. Top-of-the-line machines like 5-axis milling machines often produce better cuts and tolerances. Also, using better equipment can reduce lead times and get the product into your hands faster.

2. Competitive Rates

Like we’ve mentioned multiple times above, CNC prototyping can be a bit expensive. To reduce costs, it’s better to get quotes from different vendors. Doing this lets you compare their rates to see which one is best for your budget.

3. Industry-Specific Experience

A machine shop with experience in creating prototypes for your industry can make a whole world of difference. The standards and codes required for products vary from industry to industry. A machinist who has experience creating for a specific industry would do a better job than one who doesn’t.

4. Proper Certifications

The different quality and safety certifications owned by a machine shop say a lot about it. Machine shops with highly rated quality certifications will deliver top-notch service. ISO 9001 is an example of a certification that every shop should have.


At RapidDone, we can provide all this for you. With our line of top-notch CNC machines operated by our qualified and experienced professionals, we are sure we can offer the best CNC machining services for your projects. Contact us today to get the best quotes and technical advice on your prototype. We’re at your service!

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