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CNC Machining VS 3D Printing

CNC machining is a type of subtractive manufacturing process that carves out the needed intended product out of a block of material and 3D printing is a kind of additive manufacturing process that builds the final product layer by layer. There are several similarities as well as differences between these two manufacturing methods.

Required Material and Waste Produced

The essential difference of CNC machining’s subtractive manufacturing process and 3D printing’s additive manufacturing processes suggests that they are compatible with different materials and produce a distinct amount of waste. Since CNC machining involves only carving the shape out, it has a wide range of material options from plastic, metal, wood, wax, and almost any kind of material. On the other hand, 3D printing has more limited available choices. In general, the common 3D printing materials are mostly only plastics such as PLA and metals such as aluminum.

In addition, due to the fact that CNC machining carves the intended product out of a block of original material, it usually produces wastes that can hardly be recycled. However, since 3D printing creates the product out of scratch, it does not leave much waste after finishing building the model.

Size, Accuracy, and Time

The products made by CNC machining and 3D printing are distinct in terms of size, accuracy, and the time it takes to manufacture them.

For CNC machining, it can produce products sizing from very large to significantly small with high precision. In contrast, 3D printing has more restrictions on the size of its product. Since 3D printing creates its final product layer by layer, the minimum wall thickness determines the minimum size of the product, and the minimum wall thickness is restricted by its end effector. Other than the minimum size of products, the maximum part size is also confined because 3D printing requires close environment control. It is not impossible to produce large products by using 3D printing. However, that would require the assembling of different pieces built by 3D printing, which can take up a large amount of time.

In addition, CNC machining offers a polished surface look thanks to its higher heat tolerance. For 3D printing, however, the layer lines may be visible, especially around the curves. Furthermore, since CNC machining is a subtractive process, the time it takes to make the final product is way less than that of 3D printing. Since the process of 3D printing includes melting the materials and building the product from nothing, it is natural that it takes more time than the subtractive process of CNC machining.

Manufacturing Workflow

Both CNC machining and 3D printing involve the operation of a computer. The movement of CNC machining tools is controlled by computer software, and the process of 3D printing largely replies on the machine operator’s file as well. However, while the operation of 3D printing solely depends on the file chosen for the machine operator, CNC machining is way more labor-intensive. Besides the movement of tools, most steps of CNC machining require an expert operator to complete, including setting up the machine, tool selection, spindle speed, cutting path, and other post-processing.

Cost

As far as the price is concerned, it is largely dependent on the quantity of the product. While the unit cost of using CNC machines to make a small quantity of product can be expensive, it is ideal to choose CNC machining for mass production. The excellent repeatability of CNC machining also makes it a better choice respecting mass production. For 3D printing, on the other hand, each product produced by 3D printing has the same unit cost, regardless of how big the quantity is. Consequently, when the desired product is in large amount, CNC machining would be a wiser option.

Conclusion

In conclusion, CNC Machining and 3D printing each has its own advantage and disadvantage in different respects. When concerning the material, 3D printing is only compatible with plastics and certain metals and CNC machining can work with almost all kinds of material. However, CNC machining also leaves a large number of waste materials that cannot be recycled while 3D printing does not produce any waste. In terms of the manufactured product, CNC machining can produce products in various sizes accurately in a relatively short amount of time, but 3D printing can only build products in restricted sizes with less precision in a longer period of time. When it comes to the manufacturing workflow, 3D printing requires little human intervention while CNC machining must be operated by operators. For the price of these two processes, CNC machining would be a cheaper choice compared to 3D printing when mass production is needed.

For people who need a medium or high production volume of CNC or 3D printing parts, tasks can be well finished with the help of a professional manufacturing company. RapidDirect is an industry-leading designer and manufacturer of rapid prototyping services, whose CNC machining and 3D printing service features streamlining the manufacturing process with automation, wide range of compatible materials, a high degree of accuracy and precision and rapid manufacturing for medium to high production volumes.

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