Process differences between 3D printing and traditional CNC

Originally created as a method of rapid prototyping, 3D printing, also known as additive manufacturing, has evolved into a true manufacturing process. 3D printers enable engineers and companies to produce both prototype and end-use products at the same time, offering significant advantages over traditional manufacturing processes. These advantages include enabling mass customisation, increasing design freedom, allowing for reduced assembly and can be used as a cost effective process for small batch production.

So what are the differences between 3D printing technology and the current established traditional CNC processes?

1 – Differences in materials

The main materials used for 3D printing are liquid resin (SLA), nylon powder (SLS), metal powder (SLM) and wire (FDM). Liquid resins, nylon powders and metal powders make up the vast majority of the market for industrial 3D printing.

The materials used for CNC machining are all one piece of sheet metal, measured by the length, width, height and wear of the part, and then cut to the corresponding size for processing, CNC machining materials selection than 3D printing, general hardware and plastic sheet metal can be CNC machined, and the density of the formed parts is better than 3D printing.

2 – Differences in parts due to moulding principles

3D printing is the process of cutting a model into N layers / N points and then stacking them up in sequence, layer by layer / bit by bit, just like building blocks. 3D printing is therefore effective in machining complex structural parts such as skeletonised parts, whereas CNC machining of skeletonised parts is difficult to achieve.

CNC machining is subtractive manufacturing, where various tools running at high speed cut out the required parts according to a programmed toolpath. Therefore, CNC machining can only be processed with a certain degree of curvature of the rounded corners, the outer right angle CNC machining is no problem, but can not be directly machined out of the inner right angle, to be achieved through wire cutting / EDM and other processes. In addition, for curved surfaces, CNC machining of curved surfaces is time consuming and can easily leave visible lines on the part if the programming and operating personnel are not experienced enough. For parts with internal right angles or more curved areas, 3D printing is not as difficult to machine.

3 – Differences in operating software

Most of the slicing software for 3D printing is simple to operate and is currently optimised to be very simple and support can be generated automatically, which is why 3D printing can be popularised to individual users.

CNC programming software is much more complex and requires professionals to operate it, plus a CNC operator to operate the CNC machine.

4 – CNC programming operation page

A part can have many CNC machining options and is very complex to program. 3D printing, on the other hand, is relatively simple as the placement of the part has a small impact on the processing time and consumables.

5 – Differences in post-processing

There are few post-processing options for 3D printed parts, generally sanding, blasting, deburring, dyeing, etc. In addition to sanding, oil blasting and deburring, there are also electroplating, silk-screening, pad printing, metal oxidation, laser engraving, sandblasting and so on.

In summary, CNC machining and 3D printing have their own advantages and disadvantages. Choosing the right machining process is even more important.

Post time: Nov-02-2022


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