CNC Machining vs 3D Printing:10 Considerations Before You Choose Between the Two

Material

The first consideration is perhaps the most important one as the material is still the biggest technological constraint for 3D printing.
As stated before, it’s possible today to 3D print different materials ranging from metals to ceramics.
However, there are still many limitations when it comes to the overall mechanical properties of your part.

For instance, 3D printed metal parts don’t come with that much fatigue strength and may also need a lot of heat treatment before they are ready to use. This can cause the overall cost to skyrocket and make the process unfeasible for your business.
CNC machining would be a better choice in this regard as it can quickly process metal and doesn’t require any heat treatment.

Production Volume

This is another important consideration that determines the right manufacturing process for you. The manufacturing industry has relied on the economies of scale concept for the longest time. This means that the more parts you produce, the more cost-effective your production will be. Today, both CNCs and 3D printing play a part in volume production.

On one side, CNC machines automatically create the required part with minimal human input while working 24/7. On the other hand, 3D printing is a common choice for creating prototypes and even complex molds for further volume production using methods like casting. However, if volume production is the deciding factor, most go with CNC machining because of the cost overheads and the fact that there is no other process involved.

Size of the Part

Another essential consideration while deciding between CNC vs 3D printing is the size of the part. Generally, CNC machines can handle bigger parts because of their size. 3D printers have so many associated costs that make going beyond a certain size unfeasible. In this case, the best approach is to consider the specifics of the project. However, the general principle that CNC is a better choice for larger parts holds true in most cases.

Design Complexity

This is an area where 3D printers shine. Since they develop directly from the CAD model, there are almost no designs that 3D printers can’t handle. Machining, whether traditional or CNC design requires a lot of input from experts to ensure that there are no hindrances to the cutting tool.
Thereby making a lot of complex designs either impractical or impossible.
On the other hand, 3D printing is not only free from all these restrictions.
It can also go a step above and handle hollow designs and other features that are not possible for other manufacturing techniques.

Dimensional Accuracy

The dimensional accuracy you need will also have an effect on the right technique for you.
Both CNC machines and 3d printers are quite accurate and deliver consistent results.
However, CNC machines still depend on the initial input from the operator and the G/M codes.
3D printers don’t have that issue and give you consistent results.
Their difference is, however, quite small and negligible for most common applications.
Therefore, CNC and 3D printing stand toe-to-toe in this regard.

Surface Finish

This is one area where CNC machines are the clear winner.
Given the right conditions, CNC machines will deliver a better-quality surface finish when compared with 3D printers.
The main reason behind the difference is the fact that 3D printers are designed for prototypes and parts that need further processing.
CNC machines are made to create final products that are ready for the market, so their surface finishing capabilities are much more advanced.

Speed

Generally, CNC machines can cut out pieces much faster than 3D printers.
However, the overall time is not dependent on the cutting rates only.
The machine’s starting time and other pre-processing requirements along with other factors determine the overall speed of the process.
The size also plays a part. The general rule of thumb is that for smaller pieces, 3D printers are a quicker option as they start making the part immediate.
However, CNC is the right choice for larger parts.

Post-Processing Requirements

Generally, CNC machines deliver a part that is 100% ready for the market. 3D printers are a little different.
Their common applications are related to prototyping or assisting in mold creation.
For both cases, a rough surface finish works just fine. Otherwise, you’ll have to further process the part before it’s ready for any other application.
Apart from that, metal 3D printed components even have another requirement of heat treatment.
Because of how 3D printing works, the developed part doesn’t have much fatigue strength and impact properties.
Heat treatment allows the internal structure to set better and deliver better performance.
However, it still doesn’t work as well as CNC parts.

Eco-Friendliness

Both CNC and 3D printing materials can work with a plethora of materials.
The CNC process is generally free from harmful materials while 3D printers use more thermos plastics for prototyping.
If used correctly, they can be a great way to recycle the plastic that would otherwise remain in circulation for the longest time.
Therefore, depending on your application and commitment to the environment, both CNC and 3D printing can potentially be eco-friendly options.

Manufacturing Budget

Both CNC and 3DP have some associated costs.
For smaller one-off parts, 3D printers are the best choice.
However, volume production requires consistent operations and CNCs are the better options for it.