Design for additive manufacturing
Complex geometries and filigree lightweight structures, this is where additive manufacturing can show its advantages.
Whereas additive manufacturing processes were previously used mainly in prototype construction, they are increasingly gaining a firm foothold in series production as well.
The triumphant advance of the new processes is favoured by the fact that the potential arising from their use is increasingly being taken into account in design and development. This is because they can only really show their superiority when even the first sketches of principles are really thought out beyond the classical limitations of production technology. In this context, some authors also speak of cognitive barriers that first have to be overcome. Why? - Especially when it comes to cost-optimised component design, conventional and additive manufacturing differ diametrically. This is not only due to different scaling effects with regard to the number of pieces to be produced. Many advantages can be found in areas that were previously considered cost drivers. It is therefore worth taking a closer look at the approaches behind the concept of "design for additive manufacturing".
Design for additive manufacturing - The potential is enormous
As with other Deign for X concepts, "Design for additive manufacturing" is not a closed set of rules in the sense of a guideline, but rather a collection of recommendations that can be derived from the advantages of the processes.
The field of additive manufacturing and the associated manufacturing processes are developing rapidly. Potentials that arise, for example, through the possibility of combining different materials in one manufacturing step, are still in an early phase. Nevertheless, I would like to take this opportunity to discuss the main advantages.
Component complexity
The production of complex components is no more cost-intensive and in many cases even cheaper than printing simple geometries, for example. Whereas complex used to be considered the same as expensive, this is not the case with many additive processes. Because it is precisely in this point that the biggest difference in approach becomes apparent. If you start with a raw part and create a geometry by removing material, each processing step increases the costs enormously, while the material costs are negligible. Exactly the opposite is true when applying material. Any volume of material that must first be created increases production time and material costs. This is why supposedly simple components are very expensive in 3D printing, whereas complicated support structures that would be impossible to produce conventionally or would hardly be affordable can be produced economically.
Moving parts without assembly
Additive manufacturing enables a whole new type of functional integration. Hinges, chains or other moving parts that require multiple joining and assembly operations can now be produced in just one manufacturing step.
Material integration
Jam on the inside, dough on the outside. Similar to the possibility of producing constructions that were previously not possible, the boundaries are also increasingly shifting with regard to the material structure. The targeted use of different material properties is thus becoming even easier.
Structural complexity
Whenever the strength-to-weight ratio needs to be optimised, additive manufacturing opens up completely new options. Lattice structures, honeycomb geometry or foamed material enable lightweight construction on a new level. Since lightweight construction is a key technology for saving energy in many areas, there is no way around the necessary manufacturing technologies for this reason alone.
Intuitive design and manufacturing process
In the past, the development and design of new elements always presupposed knowing exactly how the component would be manufactured and assembled. Of course, this is also the case with design for additive manufacturing, but the degrees of freedom are much greater here.
Better material utilisation
It is inherent in the nature of additive processes that only as much material is applied as is needed. Consequently, resource efficiency is also better from this point of view.
Design process - from the functional surface to the finished component
Construction is often a creative and open-ended process in which, as is well known, many roads lead to Rome. In addition to functional requirements, aesthetic sensibilities also play a role. Nevertheless, it is advisable to start with the design of the functional surfaces and then approach the optimal design using the finite element method (FEM). Accordingly, the ideal design process for additive manufacturing processes can be divided into four steps.
Design process for additive manufacturing
-
Initial shaping
The rough shape of the component is worked out based on the required interfaces to other components, which are also referred to as the effective or functional area. This makes sense, as the load spectrum acting on the later component is naturally determined to a large extent by its interaction at the geometric and energetic interfaces.
-
Determination of further parameters and boundary conditions
In this step, it is a question of determining all requirements that must be fulfilled. In addition to the requirements for the effective areas, restrictions may arise with regard to the available installation space or other factors.
-
Parametric optimisation
Once the requirements have been clearly defined and the conceptual questions have been clarified, the optimal design must be determined in terms of material and energy consumption as well as processing time and costs. This is done by successively removing material and using finite element analysis to check whether the load requirements are met.
-
Manufacturing simulation
Finally, it must be ensured that the optimised mould geometry can also be produced. This is done by simulating the machining process in a virtual machine.
Future technology on the way to mass application
Although additive processes do not yet have a comparable level of process maturity to conventional technologies, it can be assumed that their spread will grow exponentially. This is primarily due to the opportunities that arise in lightweight construction and the trend towards decreasing quantities with simultaneously increasing component complexity.
The fact that additive manufacturing is on the advance is also shown by the fact that all well-known manufacturers of machine tools now have corresponding systems in their product range or want to invest in this technology.
