Subtractive manufacturing processes such as CNC milling & CNC turning, CNC waterjet cutting or CNC laser cutting or additive manufacturing processes such as FDM, MJM, SLS & SLM – there are different ways to manufacture your part. But not every process can be combined with every material. In the following text, we will introduce you to the two manufacturing methods and their special features.
Subtractive manufacturing processes
Let’s start with subtractive manufacturing and imagine we want to manufacture a simple fruit bowl.
In subtractive manufacturing, a block of the material in which the part is to be made is shaped into the desired form by removing material. For example, machining can shape an initially square block of metal into a circular hemisphere. The basis for our fruit bowl. In a further step, the hemisphere can now be hollowed out with the help of a milling machine so that we can also fill it with our fruit. For a safe stand, the bottom of the hemisphere can be flattened in a final step. Of course, this is just a very simple example and there are numerous other design possibilities. For example, a part can be additionally equipped with threads, holes, pockets and other features.
All in all, a large block of material is machined until it is turned into the finished part designed in the CAD program. A major advantage of subtractive manufacturing is its high accuracy, especially when working with low tolerances. In addition, machining is very fast for large quantities.
Additive Manufacturing processes
Unlike the subtractive processes, the workpiece in additive manufacturing is created using the layer building principle, which means that the part is built up in layers.
In our example of the fruit bowl, it grows into its final image with each new layer. In most additive processes, the starting material (a powder or filament, depending on the process) is melted by heating, formed into the new shape, and built up layer by layer.
No machining tools are necessary in additive manufacturing. As a result, very complex structures can be realized and there are hardly any design restrictions. Thus, very individual prototypes and small series can be produced at low unit costs and in a reasonable time. Due to the rapid feasibility with the additive process, the production of prototypes is often referred to as “rapid prototyping“, the production of tools as “rapid tooling” and the production of end products as “rapid manufacturing“.
The question of the appropriate manufacturing process begins with the selection of the desired material and ends in the complexity of the part. For our fruit bowl, it would be easy to find the right manufacturing process, as the part can be produced using any process, but the cost per part would differ considerably depending on the process.
For extremely complex structures inside a part, such as cavities, to save weight, an additive manufacturing process is chosen. However, if a simple design and less complex structures are used, a subtractive process would be the right choice.
The batch size also plays an important role in the selection of the right process: Since additive processes are slower in production than subtractive processes due to the layer construction principle, a subtractive process is selected if possible for larger quantities.
Test our KREATIZE Manufacturing Services!
At KREATIZE we offer subtractive (CNC milling & CNC turning, CNC waterjet cutting, CNC laser cutting) as well as additive manufacturing processes (FDM, MJM, SLS & SLM). Our CNC milling service is ideal for prototyping or functional testing and you have a choice of over 400 different plastic and metal materials. Our additive manufacturing processes are capable of producing finished parts directly from 3D CAD data without custom tooling.