Modern Manufacturing requires precision, repeatability and reliability. With 3D printing and CNC machining being adopted by those in a broad range of industries, it has become considerably easier for designers and machinists to deliver accuracy and reliability time and time again.
Each produces offers unique strengths, but which is the best for your project?
What is CNC machining?
CNC precision machining (Computer Numerical Control machining) is a manufacturing process that uses computer-controlled tools to create parts with exceptional accuracy and repeatability. For jobs that require constant precision, it’s invaluable, as once the code has been generated, the process can be repeated an infinite number of times, delivering consistent high-quality results. Furthermore, CNC precision machining can also be used in the production of complex 3D shapes, something manual machining often finds difficult to achieve.
CNC machining is a subtractive process. The machine begins with a solid block of the required material, typically metal or plastic. A CAD model is created, and CAM software converts the design into toolpaths. Using the created G-code, the machine cuts away at the material until the final part is created.
What is 3D printing?
3D printing is a manufacturing process that, like CNC machining, creates complex designs with repetitive accuracy and precision. First rising to prominence in the 1980s, it was initially considered suitable for functional or aesthetic prototypes; however, technological developments now see many 3D printing techniques considered ideal for industrial production.
Its ability to produce complex shapes or geometries that are considered impossible to execute by hand has seen it utilised by many industries.
Where CNC machining works as a subtractive process, 3D printing is additive. It creates an end product by carefully building thin layers of material. With a 3D model created on CAD software, it is then sliced into thin horizontal layers. The printer then follows instructions, depositing materials onto a build platform, layer upon layer, until the object is complete.
What are the benefits of CNC machining?
CNC precision machining provides design and manufacturing teams with an efficient, reliable and cost-effective way to construct items repetitively, for use in a range of industries.
Many choose CNC machining as their optimal manufacturing solution because:
Exceptional precision and surface quality
CNC machines consistently achieve tight tolerances, making them ideal for high-performance applications including aerospace, medical and automotive parts.
Compatible with a range of materials
CNC machining can be used on metals such as steel, titanium and aluminium as well as engineering plastics. The finished result remains just as strong as the material used, resulting in a high-quality end product without structural integrity compromised.
Suitable for load-bearing parts
CNC machining is adopted by manufacturers whose products are put under intense strain. Aerospace components, automotive parts, medical equipment and industrial machinery can all be created through CNC precision engineering.
Fast turnaround and optimised productivity
CNC machining is fast, enabling a consistent and reliable production of hundreds, even thousands of parts, much quicker than if they were fashioned by hand or by alternative manufacturing methods.
What is CNC precision machining best used for?
CNC precision machining really comes into its own when used for the creation of:
- High-precision parts
- Metal components
- Parts requiring tight tolerances of strength
- End-use components rather than prototypes
Additionally, it’s a preferred method of manufacture when production runs require mass fabrication within very short deadlines.
What are the benefits of 3D printing?
3D printing offers manufacturing teams an efficient way of bringing a product from concept to functional prototype or low-volume component. Many teams choose 3D printing because:
Versatile designs
3D printing can create shapes, structures and internal channels that are difficult, and in some cases, impossible to machine. This helps reduce wastage, speed up productivity and deliver consistent results.
Its fast
3D printing is ideal for rapid prototyping. It’s easy to go from the initial design to a physical part in just hours. This allows teams to test sooner and refine if necessary. Furthermore, where visual models or demonstration products are required, 3D printing delivers a rapid scale-out of prototypes or dummy products at low cost and at rapid speed.
Low cost
3D printers do not require tooling or fixturing. A simple installation and integration with CAD software means you can be up and running in no time at all.
Waste-efficient
A 3D printer only uses the materials it requires for the part. This means no wastage, which means reduced overheads and an enhanced bottom line.
What is 3D printing best for?
Where CNC precision machining is typically used for end products, 3D printing perhaps lends itself more to early-stage design or products built in low volume. It’s often chosen as a manufacturing tool for:
- Prototypes
- Complex or lightweight designs
- Low-volume custom parts
- Concept models
How does CNC machining compare with 3D printing?
We’ve created a handy table demonstrating some of the key features of both CNC machining and 3D printing. Whilst both deliver exceptional quality, some features outweigh others and may make one more preferable than the other for your manufacturing processes.
| Feature | CNC Machining | 3D Printing |
| Process | Subtractive | Additive |
| Best materials | Metals & engineering plastics | Plastics, resins & some metals |
| Strength | Very high | Moderate |
| Precision | Excellent | Good |
| Costs | High for prototypes, low for production | Low for prototypes, high for large parts |
| Speed | Fast for production | Fast for prototypes |
From this brief table, it appears that CNC machining delivers a higher quality of production, but depending on your industry and the requirements of your design, 3D printing can be extremely beneficial.
You should choose CNC machining for projects that require:
- Tight tolerances
- High mechanical strength
- Smooth finishes
- Metal parts
- High production volumes
This would include brackets, housings, gears, manifolds and medical components.
3D printing becomes preferable if your project is for:
- Prototypes
- One-off custom designs
- Lightweight items
- Complex internal geometries
Examples benefiting from 3D printing would include concept models, custom enclosures and fixtures.
Can CNC machining and 3D printing be combined?
Yes, they can, although not at the same stages of production. To ensure costs are kept down and the end result matches the exact spec, many businesses use 3D printing for early prototypes and then CNC machining for final production.
This enables a much more efficient process, as any necessary tweaks to the final design can be made before the product is sent to the CNC team. With a quick printout from the 3D printer, design teams can finesse the product, tackling any issues that may arise upon review of the prototype.
So which process should I choose?
Whether you choose 3D printing or CNC machining depends on the complexity of your design, your budget, the production volume and the materials being used. Both technologies offer powerful and reliable build solutions, and when combined, refine your processes to reduce waste and expenditure whilst enhancing productivity and efficiency.
- Choose CNC machining for precision, strength and large production.
- Consider 3D printing for fast prototyping and complex or custom geometries.
