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Additive Manufacturing vs. CNC Machining – Which is Best?

In today’s world of advanced manufacturing technology and processes, consumers have a variety of options to choose from to bring their designs to life. 

With how fast limitations and opportunities can change in these industries, it may be difficult to keep up with or even comprehend the differences. However, metal additive manufacturing is rapidly growing and uncovering potential applications every day. 

Let’s take a closer look and compare additive manufacturing and CNC machining.

The Difference Between Additive Manufacturing and CNC Machining

While both processes have the ability to work with metal and produce components, there are significant differences.

Additive manufacturing is the process of creating a component through the distribution of powder material and an adhesive binder. Metal AM has the ability to handle nearly any complex design whether through mass-production or rapid prototyping. While at the same time, maintaining a low cost of production.

CNC machining (computer numerical control machining) is the process of using automated machining tools via the power of a computer. The operator programs a specific design into the software, translates it to the machine, and then makes the part. This process is one of the most effective machining processes that manufacturers can use and reduces the need for highly-trained experts.

Pros & Cons of Additive Manufacturing

Now that you have a basic understanding of additive manufacturing and CNC machining, we can dive into the pros and cons of each. Let’s start with additive manufacturing.

Additive Manufacturing Advantages

The pros of additive manufacturing far outweigh the cons, and the process only continues to improve. Advances in manufacturing technology allow the process to become more relevant and strengthen its current advantages.

Three advantages of additive manufacturing include:

  1. Reduced, minimal waste
  2. Makes cost-effective, complex parts
  3. Vast material choices available

1. Reduced, Minimal Waste

Unlike other manufacturing processes, additive manufacturing only uses what’s needed to produce a particular product. There’s very minimal waste, with the only excess consisting of any support structures that were made during the manufacturing process. 

In some cases, these support structures are added to help ensure that the part being created maintains the shape it was designed to have.

2. Makes Cost-Effective, Complex Parts

If you took an extremely complex design to a CNC machining manufacturer, you’d most likely turn it down after receiving the cost estimate. 

On the other hand, the additive manufacturing process starts from ground zero (as opposed to starting with a raw block/slab and removing material), so it’s much easier to create complex parts at a reasonable cost.

3. Vast Material Choices Available

Although APG focuses on metal additive manufacturing, there are several other material choices that can be used for an AM component to meet design requirements. These include:

  • Thermoplastics
  • Ceramics
  • Biochemicals

Each one of these categories has several material subtypes. Even if you need an extremely lightweight material that’s durable enough to withstand impact, additive manufacturing can handle it. 


Additive Manufacturing Disadvantages

While there are several benefits to additive manufacturing, there are two main cons:

  • Employing AM is capital-intensive
  • The build rate is slower compared to other processes

Employing AM is Capital-Intensive

Certain technology needed for this additive manufacturing can cost upward of $2,000,000. Although the process is cheap to run, the machinery needed is very capital-intensive.

Pro Tip! Instead of providing a large, upfront expense, seeking out a metal additive manufacturing company that already has the equipment in place can drastically reduce your costs.

The Build Rate is Slower Compared to Other Processes

One of the most unfortunate additive manufacturing disadvantages is that the build rate is a bit slower than other processes. Most printers lay down chosen material at a speed of 1-5 cubic in. per hour. Therefore, bigger parts may take a bit longer than desired

However, certain AM machines can produce components much quicker, with some able to achieve speeds of 732 cubic in. per hour. However, these types of speeds are still slowly trickling into the industry. 


Pros & Cons of CNC Machining

Similar to the additive manufacturing process, there are also pros and cons of CNC Machining.

CNC Machining Advantages

CNC machining offers two many advantages:

  • Ease of operation
  • Minimal supervision necessary

Ease of Operation

CNC machines take the headache out of manufacturing with ease of operation. Once a design is programmed into the machine, it does the rest of the work by itself (mostly). 

This is beneficial because highly-trained operators don’t need to run the machines, reducing the total cost of production labor.

Minimal Supervision

Once a CNC machine is programmed, it can run continuously until it needs maintenance. CNC machines can run for 24 hours a day, 7 days a week, giving it the ability to handle high-volume orders with ease. 

CNC Machining Disadvantages

Depending on who you ask, the cons of CNC machining can far outweigh its pros. Some of the biggest disadvantages of CNC machining include:

  • Material waste
  • High cost of operation

Material Waste

Unlike additive manufacturing, CNC machining is a subtractive manufacturing method that starts with a block of raw material and removes it bit by bit using rotating tools until it achieves the desired shape. 

It’s not uncommon for CNC machining to produce a 50% scrap rate -- which you ultimately have to pay for.

High Cost of Operation

Although having constant run time can be beneficial, the amount of energy needed to run these machines, CNC machines tend to have a much higher cost of operation.

Which Method Should You Choose?

The manufacturing method that you should choose will depend a lot on the type of part being produced, and what its application will be. Taking the pros and cons of each method into consideration is necessary.

Finding a Manufacturer

Fortunately, at Alpha Precision Group our team has experience across several manufacturing methods to find the best solution for your application.

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