3D Printing vs CNC Machining: Which is best for Prototyping?
3D printing and CNC machining are both rapid manufacturing processes used to create parts or components in various industries. Currently, our rapid prototyping relies significantly on these two manufacturing processes.
CNC machining operates through subtractive processes, while 3D printing relies on additive techniques. 3D printing vs CNC machining, do you know what is the best option for your rapid prototyping project?
This article delves into a comprehensive comparison between 3D printing and CNC machining, read through, it will help you to choose the right method for your prototyping project.
3D Printing vs CNC Machining: Process
3D printing, also known as additive manufacturing, constructs objects by layering bonded slices to form a 3D structure akin to a stack of images with a finite thickness.
CNC (Computer Numerical Control) machining achieves similar outcomes but through subtractive manufacturing, sculpting the desired shape from a solid block by utilizing rotating tools or by spinning the workpiece or both.
3D Printing vs CNC Machining: Materials
Materials used in 3D printing mainly include liquid resin, nylon powder, metal powder, sandstone powder (full-color printing), filament, and so on. Liquid resin, nylon powder, and metal powder dominate the vast majority of the industrial 3D printing market.
On the other hand, the materials used in CNC machining are all sheet-like materials, cut into corresponding sizes based on the measurements of the component’s length, width, height, and waste, and then used for processing.
CNC machining offers a wider selection of materials compared to 3D printing. Generally, metal and plastic sheet materials can be used for CNC machining, and the density of the formed parts is typically better than that of 3D printing.
3D Printing vs CNC Machining: Geometric Complexity
As mentioned earlier, 3D printing is an additive manufacturing process that slices models into N layers/N points and then builds them up layer by layer/point by point in sequence, similar to assembling blocks. Therefore, 3D printing can effectively produce complex parts with intricate structures, such as hollow components, which can be challenging to achieve with CNC machining.
CNC machining, on the other hand, is subtractive manufacturing, where various tools rotate at high speeds to cut out the required components following programmed tool paths. CNC machining can only create rounded edges with a certain radius and cannot directly produce internal right angles, which require processes like wire cutting/EDM to achieve. External right angles are feasible with CNC machining. Parts with internal right angles may be better suited for 3D printing.
Moreover, concerning curved surfaces, if a part has a significant number of curved surfaces, it is advisable to choose 3D printing. Machining curved surfaces with CNC is time-consuming, and insufficient programming or machining experience can lead to noticeable patterns on the components.
Differences in software operation:
Slicing software for 3D printing is generally straightforward to operate, allowing even novices to become proficient under professional guidance in a day or two. The simplicity of slicing software optimization enables the widespread adoption of 3D printing among individual users.
In contrast, CNC programming software is more complex, requiring skilled professionals for operation. Beginners usually require around half a year to learn. Additionally, a CNC machine operator is needed to run the CNC machine.
Due to intricate programming, a single part may have multiple CNC machining approaches, whereas the impact of the placement position on processing time and material consumption is minimal in 3D printing, making it relatively more straightforward.
3D Printing vs CNC Machining: Cost
3D Printing: For low-volume production or prototyping, 3D printing can be cost-effective due to minimal setup requirements and the ability to produce complex designs without additional tooling costs.
CNC Machining: While CNC machining may have higher initial setup costs (tooling, programming, etc.), it can be more cost-effective for larger production runs due to its speed and efficiency.
3D Printing vs CNC Machining: Speed and Efficiency:
3D printing can be slower compared to CNC machining, especially for producing larger parts or high-volume production. The speed of 3D printing depends on factors like the complexity of the design and the chosen printing technology, but one processing cycle may need serval hours or over 24 hours.
CNC machining is generally faster for producing parts once the setup is complete, the manufacturing process normally can be finished within several hours.
3D Printing vs CNC Machining: Differences in post-processing:
There are fewer post-processing options for 3D printed parts, generally including polishing, painting, deburring, and so on. In contrast, the post-processing options for CNC-machined parts are diverse, encompassing activities like plating, screen printing, pad printing, metal oxidation, laser engraving, sandblasting, among others.
Conclusion:
While 3D printing offers advantages like the ability to create complex geometries, rapid prototyping, and lower setup costs, it may lag behind CNC machining in terms of surface finish, material limitations, and strength, particularly for high-volume production. CNC machining, on the other hand, provides benefits such as material versatility, precision, excellent surface finishes, and strength, but comes with drawbacks such as complexity in handling complex geometries, and higher waste generation. Understanding the strengths and weaknesses of each manufacturing method is crucial in selecting the most suitable process based on specific project requirements, volume considerations, material needs, and desired outcomes.
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FAQ for 3D Printing vs CNC Machining:
1. Which is better, CNC or 3D printing？
CNC machining offers high precision, excellent surface finishes, and strong materials. 3D printing excels in rapidly prototyping complex geometries and customized designs, making it ideal for small-batch production and artistic creations. Consider factors such as design complexity, material properties, production volume, cost, and time constraints to determine which method better suits your needs.
2. Can 3D printing replace CNC?
While 3D printing has advanced significantly and offers unique advantages, it can’t replace CNC machining in terms of precision and post-processing.
3. What is the difference between CNC and FDM?
CNC machining involves subtractive manufacturing, where a computer-controlled machine precisely removes material from a solid block to shape the final part according to a digital design.
FDM is a type of 3D printing that falls under additive manufacturing. In FDMa printer deposits layer upon layer of thermoplastic material to build up the desired object based on a 3D digital model.
