Both CNC machining and 3D printing have sped up the manufacturing process. Both can be used in a variety of applications. Advancement in technology for both types of manufacturing has also added to their capabilities. So, the question you may be wondering about is "which process is best for my application?"
While both types of manufacturing are exceptional tools in the arsenal of an engineer, their unique benefits make each more suitable for different situations. Let's take a look.
Cost and Time Considerations
1. Setup cost: The setup time for producing a part on a CNC machine requires expert manual input, whereas startup planning for a 3D printer is highly automated. Therefore, for a single part or small volume production runs, using a 3D printer is generally the cheaper option.
2. Material cost: CNC machining is a subtractive process. 3D printing is an additive process. That means if a part is milled on a CNC machine, a specified size of a blank has to be used where the material will be removed to make the part. You will have to pay for the complete amount of material needed to start the process.
In contrast, on a 3D printer, a part is made by adding material. Material is added layer by layer until the part is complete. This means that less material is needed to manufacture the part. Therefore, the material cost may be cheaper using a 3D printer as opposed to a CNC machine.
3. Amount of time needed: Turnaround time for 3D manufacturing is generally 2 to 5 days. If necessary, parts can be delivered within 24 hours. Turnaround time for a part made on a CNC machine is generally five days plus.
Dimensional Accuracy and Part Complexity
1. Dimensional accuracy: CNC machining provides tighter tolerances than 3D printing. These tolerance levels can be maintained on very large or very small parts. Modern 3D printers can provide good tolerance levels, just not as strict as a CNC machine.
Getting a 3D printer and a CNC quote and doing a cost comparison to a tolerance level needed should help in making a good process decision.
2. How complex is your design?: CNC machines are limited on how the geometrically complex of a part it can produce. Oftentimes, complex parts are broken into units, produced, and assembled to get the complete part. A 5-axis CNC machine can make more complex parts than a 3-axis machine, but it still has limitations and comes at a higher cost.
The ability to produce highly complex geometries is one of the key strengths of a 3D printer. It has very few geometric restrictions when compared to a CNC machine.
Quantity of Parts Needed
A decisive component as to whether it would be better to use a 3D printer or CNC machine to have your part(s) made is the number of units you need.
1. If using a plastic material: For quantities of one to a few hundred, using a 3D printer may be the best choice. For quantities of a few hundred to a thousand, then a CNC milling machine may be the best choice.
2. If using metal materials: Both processes can be considered, but for more than ten units, having them produced on a CNC will probably be more cost-effective unless the geometry is too complex for a CNC.
You will also need to consider that some metals are too hard to be tooled. In those cases, a 3D printer will need to be used.
3D Hubs is available to help you make the right decision. As an expert in this field, and has produced more than 3,000,000 parts, we can help you determine the fastest and most economical way to manufacture your parts. Get a CNC quote from us today.