Product designers and engineers who consider CNC machining vs. 3D printing need to evaluate the capabilities, lead time, and cost of each production workflow before deciding on the best course. CNC is one of the most popular manufacturing methods for low-, medium- and selective high-volume production. In contrast, 3D printing is growing more popular due to speed, cost, design freedom, and scaling agility.
Both technologies have their advantages and disadvantages in product development and prototyping or production environments. The differences combined with the final application are crucial to consider when choosing the right manufacturing workflow for your business. Manufacturers can better serve their clients if they understand how additive processes work compared to subtractive ones like CNC milling.
Comparing CNC Machining vs. 3D Printing
The main distinction between 3D printing and CNC machining is that 3D printing is an additive manufacturing process, whereas CNC machining is subtractive. CNC machining begins with a block of material and removes it with cutting tools to generate the finished product. Cutting, milling, routing, and lathes ultimately form the object. After cutting, CNC machined parts require further post-process including deburring, grinding, polishing, and rework or replacement if dimensions do not meet the required specifications.
3D printing, also known as additive manufacturing, creates products by layering materials such as plastic filaments, resins, and plastic or metal powders. Using an energy source such as a laser, UV light source, or heated extruder solidifies the material layers.
Overall advantages of 3D printing include its geometric freedom allowing designs that are not CNC machinable or injection moldable and the ability to produce highly complex parts with no additional production time or cost. In addition, improvements in 3D printing accuracy, speed, and ability to cut costs and weight in parts furth separate it from CNC machining. In contrast, general advantages of CNC machining include high dimensional accuracy and compatibility with a wide range of materials, including wood, metals, and plastics.
The following factors give a more in-depth comparison of the two:
Simplicity and Convenience
3D Printing: This process is simpler than CNC machining overall not requiring highly-skilled labor. After preparing the CAD file, you can begin printing after choosing the part orientation, fill, and support structures as needed. 3D printing does not require a highly-skilled operator to set up or operate a machine. Anybody in an office can be trained to use a printer. No supervision is necessary once printing has begun, and post-processing is typically very minimal. Manufacturing batch design can be created remotely and then sent directly to the printer for the operator to print.
CNC Machining: This is a far more labor-intensive process and requires highly-skilled labor to produce quality products. It requires a skilled operator for tooling choices, rotation speeds, cutting paths, and any necessary repositioning. CNC machines must be programmed by an engineer to run safely and accurately. There are also much more significant post-processing steps.
Accuracy and Geometric Complexity
3D Printing: 3D printing is well-known for its advantages in creating parts with high geometric complexity. 3D printing can create parts with geometries that no traditional manufacturing method can replicate, with extremely high accuracy when using advanced 3D printers.
CNC Machining: This process is also highly accurate, but it takes a lot of time to achieve this accuracy and has product design limitations ed due to the following constraints: tool access, holds or mount points, and square corner geometry.
3D Printing: On average 3D printing is cheaper, but costs depend on part requirements and how quickly you need them. For low volumes and quick turnaround, 3D printing is more appropriate and cost-effective. 3D printing is also a more economical route for rapid prototyping.
CNC Machining: For larger quantities and large parts, CNC may have more cost-effective. However, CNC machining incurs higher labor costs due to setup time, tool path programming, and machine management while the subtractive process produces a significant amount of waste. For example, large, lightweight parts can result in up to 90% waste material with CNC machining.
3D Printing: Since additive manufacturing forms a part from material fed into the machine, voxel by voxel, there is little material waste. Outsourcing to Smart Factories on-demand production services ensures the lowest material use with optimized workflows that minimize support structure, reclaim unused resin, and regenerate detergents to maximize production sustainability and minimize material and consumable costs.
CNC Machining: Since CNC involves cutting material away from an original block, there will always be material waste and, at times, an excessive amount. Post-processing steps also add to waste. CNC machining requires the material being cut to be bathed in coolant during the machining process. This coolant has a limited life cycle and can only be used a few times before being discarded.
The table below gives a brief comparative overview of the two processes:
|CNC Machining||3D Printing|
|Speed/Workflow||Requires extensive time to understand the product requirements, setup, and program the CNC machine. Once programmed, it can be highly automated.||Production speed depends on the printing volume and z-axis speed. Programming is very simple and can be done by people with very little training.|
|Post-processing||May require sanding and additional post-processing steps such as coatings or painting.||Post-processing depends on the additive manufacturing process. It can include removal of support structures, curing, sanding, etc.|
|Materials||Aluminum, plastics/polymers, wood, and some composites. Very limited support of elastic materials.||Supports a range of standard and advanced materials, including metals, plastics/resins, and biocompatible materials.|
|Accuracy||Highly accurate.||Highly accurate enables greater design complexity.|
|Cost||Tooling, programming, and machine time are amortized across production volume. Per-unit cost is lower with higher volume production.||Per-unit cost is dependent on the amount of material used to produce the product and machine time. The cost per part is consistent regardless of the number of parts made.|
|Waste||Starts with a large block of material and removes material leading to more material and post-processing waste.||Uses only material required to produce the part, which involves very little waste.|
|Labor||Requires specialized, highly skilled laborers to program the CNC and troubleshoot issues.||Advanced 3D printing solutions require less labor and a lower skill set.|
Which is Better?
When we compare CNC machining vs. 3D printing, we can see that additive manufacturing simplifies the production workflow, delivered parts faster, lowers part cost, and supports greater design freedom and business models. Because 3D printing does not require tooling, it is ideal for one-off prototyping and high-mix, low-volume, or on-demand production. For products like medical equipment, footwear/orthotics, and dental appliances, it also enables customization that is unattainable with traditional manufacturing processes.
In contrast, subtractive manufacturing can provide high throughput for a single product fabricated from common materials. This high throughput makes subtractive manufacturing processes ideal for high-volume manufacturing of simple parts. However, subtractive processes with large MOQ (minimum order quantities) are financially risky for new product introduction in an untested market and cannot produce complex designs. With greater flexibility and design freedom, lower manual overhead, and support for elastic materials, additive manufacturing may be the better choice for rapid prototyping, greater production agility, and high customization.
Regardless of which route is best for your company, LuxCreo can help. LuxCreo’s integrated Smart Factory industrial 3D printers, Smart Factory on-demand production services, high-performance materials, and intuitive software simplify manufacturing allowing you to deliver accurate, high-performance parts quickly and efficiently.
LuxCreo’s advanced Smart Factory 3D printing solutions use LuxCreo’s LEAP (Light Enabled Additive Production) platform to deliver next-generation additive manufacturing capabilities that support medical, dental, industrial, consumer, and many more industries. If you decide additive manufacturing is right for your needs, contact us to learn more about how LuxCreo’s Smart Factory 3D printers can help you scale with rapid innovation and on-demand production to simplify and lower the risk of bringing your new innovated products to market. For more information on how our services can improve your manufacturing processes, visit our contact page or call (650) 336-0888.