3D printing is one of the technologies that is set to change manufacturing for better. The capability of 3D Printers to print almost everything – from plastics to metals and from ceramic to wood is revolutionizing manufacturing, especially since it can now be done even by small manufacturers. The low investment required for simple 3D Printers and the open availability of design files has changed product fabrication and prototyping. When it was first introduced, additive manufacturing (or 3D printing) began with commercialization of stereo lithography process in the late 1980’s. It was limited to prototyping parts made of plastics, but the technology has now evolved into complete additive manufacturing chain covering design, and rapid prototyping of functional objects as well as complete devices made of plastics, polymers, metals and even concrete. 3D printing efficiently facilitates product model driven operations based on 3D CAD file. The 3D geometry of the object is converted into a series of motion commands for a 3D Printer by a class of geometric algorithms known as slicers. One of the salient advantages of 3D printing is its ability to create complex models and irregular topology with multi-material properties. As we will see, this is one of the reasons 3D printing is growing in popularity in various applications such as automotive, aerospace, defence, architecture and even food industry. In this article, we will discuss why 3D printing is an effective solution to manufacture objects with complex topologies.
Topology
Let us first understand what topology is. Note carefully that we use the word ‘understand’ and not ‘define’. This is because topology is relatively easier to understand than define. At the broadest level, topology is the study of surfaces. Technically, topology comprises the study of collection of objects that possess a mathematical structure. Structures in mathematics imply the ability to add or multiply mathematical objects together, or determine how far away the objects are from each other. A topological space is a collection of objects (usually referred to as points), and a mathematical structure that endows this collection of points with some coherence. This structure can be prescribed by means of a collection of sub-collections of points called open sets that can be defined algebraically. In other words, topology is concerned with the mathematical study of a collection of objects with certain prescribed structures. No need to worry if the definition of topology is still not clear. Just remember that topology explains how a material's shape can be completely transformed into new one without losing its core properties.One of the most popular examples of topology is the image of a coffee cup morphing into a torus – you can view it here. A torus is colloquially called a doughnut. From a topology point of view, a coffee mug can be morphed into a doughnut without having to break anything, so they have a similar mathematical structure.
Let us now move on to why 3D printing is a boon for manufacturing objects with complex topology.
3D Printing of Complex Topology
Most of the topology optimization techniques are carried out by collective use of Computer Aided Design (CAD), Finite Element Analysis (FEA) and different optimization algorithms in consideration of different manufacturing techniques. CAD is used to make 3D prototype file of the product to be optimized which can be directly 3D printed. FEA software is used to check the distribution of stresses and displacements throughout the product. It is useful in identifying areas of the part that are not sufficiently supporting the applied loads and not undergoing significant deformation and thus not contributing to the overall performance of the part.
To make these concepts clear, let us now take an aerospace use case to understand why 3D printing can play a vital role in topological optimization of design. The principal parts of a fixed-wing aero plane consist of the fuselage (the main body), the engine, wings, tail, stabilizers, flight control surfaces, and landing gear. It is engineering challenge to optimally design these components so that they are light weight yet sturdy, and functional yet safe. Design optimization entails finding a 'best fit solution' from a set of possible design solutions. Topology optimization software gives designers the freedom to design a part topology that is more natural but may be more complex to produce. Aero plane topology optimization deals with loads that the aero plane will be subjected to, constrained within a set of limits by maintaining a specific part stiffness and strength while reducing part mass, and manufacturability. The last criterion (viz. manufacturability) is critical, because if a design that is produced by optimization software is not practical to manufacture, it is of no use. And this is where 3D printing scores big. The initial topology optimization developments considered the conventional manufacturing techniques that are either subtractive or formative. These conventional manufacturing systems have limitations in producing complex shape geometries as they have different manufacturing constraints. The rise of different 3D printing technologies that allow production of anything from plastic to metal gives designers the freedom to produce complex shape geometry that is not possible to achieve by traditional methods. This is so because in 3D Printing, the systems do not require any tooling for producing a part. Additive manufacturing (AM), aka 3D Printing, is a manufacturing process where material is added through deposition or melting in a layer-by-layer fashion. Additively manufactured parts are 'built' from the bottom up, allowing production of intricate designs without extra effort on the part of the engineer or technician to compromise on the design. Topology optimization is an iterative process, and the rapid prototyping ability of the 3D Printers reduces the delay between design and testing. With 3D printing of components, it is possible to get near-instant feedback from the field as to what is needed in order to improve the design. Innovative design and 3D printing therefore go hand in hand. This is just an example; there are many other engineering areas where the combination of topology optimization and 3D printing is proving to be a win-win combination.Industry leaders like Stratasys are not only bringing out better and more cost effective 3D Printers; they are also coming up with innovative 3D printing material. Because of these positive points, 3D Printers capable of printing topology-optimized components are becoming mainstream in the field of engineering. Countries like India, which have quite a few manufacturers in the engineering domain, are sure to benefit from 3D printing in fine tuning their products.