1. Introduction to additive manufacturing
2. Processes of additive manufacturing
2.1. Rapid Prototyping
2.2. Rapid Manufacturing
2.3. Rapid Tooling
3. Proceedings at Sinotec
3.1 SLM Process
Nowadays, additive manufacturing technologies are an integral part of modern computer-aided production. In all additive manufacturing processes, components are produced by applying material in layers in the x-y-plane. The layered construction principle in Z-direction results in 3-dimensional components. In addition to the choice of process, the accuracy of the models is strongly dependent on the infeed in the Z-direction. The smaller the infeed per layer, the more accurately the actual component is mapped. The main advantage of additive manufacturing is that very complex geometries, which can only be realized with great effort or not at all with other manufacturing methods such as CNC technology, can be produced without any problems. This results in the fact that production-related adaptations of existing designs are usually not necessary.
A further advantage is that the STL file format, due to its simple structure, has become the worldwide standard in additive manufacturing. Accordingly, no machine-specific data records are required. The data records are stored in the so-called Triangulation generated from the CAD model. The model is approximated by a large number of triangles. Due to the reduction of the CAD model to the coordinates of the triangles, your data security is also increased when exchanging data with third parties (e.g. service providers).
Depending on the process, additive manufacturing can be used to produce illustrative objects as well as end products ready for series production.
Rapid prototyping is a process in which additive manufacturing is used. Basically, this process is characterised by the fact that various models and prototypes are produced in the shortest possible time. These components intentionally only have individual properties and features of the actual end product. The aim is to examine or secure selected properties and functions (functional prototype) or visual aspects (concept model) of a product as early as possible.
In principle, this process is based on the same additive manufacturing technology. However, unlike rapid prototyping, the aim here is to manufacture products whose functional and visual properties correspond or come very close to those of the end product. In addition to the manufacturability of the product, it can also be determined whether a competitive price can be achieved.
In principle, rapid tooling can be assigned to rapid manufacturing, whereby rapid tooling is limited exclusively to the additive production of tool inserts and moulds. According to this, usable tools and their components are manufactured generatively, whereby speed is also an important factor here.
However, the speed of all 3 procedures is relative and cannot be generalised. The speed depends enormously on the geometry of the component. Often the use of these technologies makes sense if the production of a component would normally require the design and manufacture of various tools.
There are various technologies for creating the layers in the production process, which differ fundamentally in their physical principles. Since our main branches come from the metal industry, we have specialized in the following processes:
Selective laser melting was developed especially for the production of gas-tight metallic parts. In this process, powder of different materials is applied layer by layer to the construction surface of an SLM printer, which is melted layer by layer by means of a laser beam. As a result of the heat dissipation through heat conduction into the surrounding, non-melted powder, the material solidifies through a phase transition. A solid layer is formed. After a predefined lowering of the machine's construction surface in the Z-direction, the process starts again.
In addition to the mechanically resilient and gas-tight metallic parts that can be produced with this process, another major advantage of the process is the recycling rate of the material. Apart from various supporting structures, this process uses only as much material as the volume of the component requires. Depending on the process of processing the excess powder, it can be completely reused.
The Fused Layer Moldingprocess, as known as Fused Deposit Molding (FDM), is a thermal extrusion process in which a layer-by-layer application is also applied to the construction surface in the x-y-plane. In contrast to the SLM process, materials with low thermal conductivity are extruded through a heated nozzle, in which the material is brought into a liquid state, and applied to the construction surface. Due to the design (limited extrusion width), only moderate precision can be achieved with this process. Also due to the design, materials with a low melting point can be used with this process, as already mentioned. Accordingly, this method is used almost exclusively for plastics.
A significant advantage of this method and thus the decisive reason why we use this method in our company is the relatively simple, fast and cost-effective production process with which our customers receive demonstration objects in the shortest possible time. In addition, similar to the SLM process, only material is used here which, apart from the supporting structures, is also required for the model. With the right choice of material and various post-processing measures, very good surface qualities can also be achieved.