3D printing vs CNC machining. Where is mass production going?

3D printing vs CNC machining. Where is mass production going?


The question whether 3D printing will replace mass production in the future appears quite often. You can find supporters of both options, although from the perspective of a company that has been operating in the area of rapid prototyping and rapid manufacturing for over 15 years, we say yes, but only in certain areas. Rather, we draw attention to the fact that mass production itself will decrease – producers in response to rapidly changing market expectations and the fact that in developed, rich countries consumers use less and less – or rather faster and faster replacing everyday objects with new ones – series volume it will become smaller in many areas, and mass production will eventually lose its strong economic justification.
But this is a trend so far.

Today, 3D printing and mass production still interact with each other, complementing and / or substituting under certain conditions – where one of them is more profitable than the other.

Rapid prototyping is just one of the fields where 3D printing excels over mass or multi-series production. The more that the very issue of additive technologies is really broad and allows for the production of details with very different properties:

  • very fast production of cheap and single parts with a low-quality finish (FDM printing)
  • complex details with high surface quality and low mechanical strength (e.g. stereolithography, which is successfully used by jewelery and dentistry)
  • elements with high mechanical and chemical resistance, produced in low and medium series (several to several hundred details), similar to details obtained by CNC machining or injection (SLS, i.e. laser sintering of polyamide or SLM metal powders). These details have one more advantage – they can be successfully further processed, such as turning, machining, drilling, grinding, glass blasting, etc.

In the latter two, the unit cost and production time are indeed higher than with the cheapest FDM technology, but these technologies are also incomparably more advanced. However, taking into account the fact that we are able to produce elements of the quality and strength of machining on SLS and SLM machines – changes the perspective.

In projects where the number of necessary elements is limited to approx. 100 – 150 pieces, SLS technology shows a decisive advantage in terms of time and cost

First of all – launching production is much faster and much cheaper, and its modification is equally simple and non-invasive. In addition, at the same time, we are able not only to produce many elements at the same time – they can also be the same or completely different, needed for other projects, orders or devices.

The savings resulting from the consumption of materials are also important. The very names of additive technologies and waste technologies tell us a lot here. In traditional (subtractive) manufacturing methods, the amount of material waste is much greater – the manufacturing process is based on the removal of its excess. 3D printing works on the principle of overlapping successive layers (merging them in the process of solidifying plastics or sintering powders).

In addition, in the case of SLS technology, it is not required to use supports to build the geometry – for this purpose, the process uses unsintered powder, located in the working chamber. After the end of the process, up to 70% of unused powder can be used again.

Another aspect that distinguishes 3D printing technologies from those called traditional methods is the possibility of obtaining full freedom in the geometry of the manufactured elements. Additive manufacturing allows you to make elements with numerous negative angles, thin walls or elements closed inside other elements. This means that in additive manufacturing technologies we can produce not only elements unattainable in traditional methods, but also the possibility of printing as one such elements, the production of which has been performed so far in parts, then folded or assembled into one. It is about all elements that are moving, cooperating or hiding one another.

An argument often raised by engineers is the low strength of incremental elements and the limited amount of materials available. Both of these arguments can be easily refuted today – parts and elements manufactured in SLS and SLM technologies have up to 80% of the strength of injection or CNC machining elements, and their quality and durability meets 100% of even the most demanding quality standards.

Such belief builds in the awareness of some companies the belief that 3D printing will fulfill its role only at the prototyping stage. Changing this attitude allows you to quickly use the full potential of industrial additive technologies, the more so that the very implementation of an industrial-quality 3D printer in a production plant is not only relatively inexpensive (compared to CNC machines or injection lines), but also the operation of such devices is much simpler .

Important aspects that distinguish additive technologies from, for example, injection molding are:

  1. response time – from the detailed design to the finished detail within even 48 hours (we do not need to create manufacturing tools);
  2. the cost of a possible error – we can often verify design errors only after the actual production of the detail. In the case of SLS technology, the cost of such an error will be even several dozen / several hundred times lower.
  3. product life cycle – assuming that the production of several dozen parts takes about 48 hours, we can significantly reduce the costs associated with the storage of spare and operating parts. Maintaining stock levels is no longer profitable, the costs associated with the possible disposal of parts whose life cycle has expired and which we have not managed to sell also disappear.
Geometria w druku 3D SLS

Geometria w druku 3D SLS