Parts 3D printing - Many advantages, but also some disadvantages
The manufacturing processes that are summarized under the term 3D printing have been the topic on everyone's lips for quite some time and are experiencing rapid technical development. Due to the increasingly cost-efficient and also more powerful process options with shorter processing times and increasing quality of the printed components, 3D printing processes are becoming more and more attractive for industrial, but also private applications.
The 3D printing processes differ from conventional manufacturing processes, already conceptually significantly. Whereas machining processes (e.g. turning, milling, drilling) are subtractive manufacturing processes, 3D printing is an additive manufacturing process. Subtractive manufacturing processes remove material from a semi-finished product until the desired shapes and dimensions are achieved. Additive processes produce the part directly to the desired dimensions, so no semi-finished product is required or material would have to be removed.
3D printing with a wide variety of materials and processes
3D printing is already possible today with a wide variety of materials. Initially, the use of plastics was common, but this is already feasible for private use with relatively inexpensive 3D printers. More industrially applied is the 3D printing of metal components with the help of a laser-sintering process. The costs of laser sintering are considerably higher, but the components can withstand much greater stresses.
Fused Deposition Modeling (FDM)
Commonly used for 3D printing with plastic materials is Fused Deposition Modeling (FDM). In this process, a suitable plastic is first liquefied by heat and then applied in layers to a carrier plate by a print head. The applied plastic undergoes a rapid increase in viscosity, becoming solid so that the next layer can be applied. In this way, the component is built up layer by layer from bottom to top.
Laser sintering
Unlike the FDM process, 3D laser sintering does not emit a liquefied material from a print head. Rather, a powder of the desired material is fused by a laser beam. Starting from a metal support plate, thin layers of powder are successively "welded" together, similar to classic buildup welding, so that the desired component is also printed layer by layer in laser sintering. Some metals and metal alloys are suitable for laser sintering, including, for example, titanium and stainless steel. However, other alloys are unfortunately unsuitable for technical reasons and current possibilities.
Special features of laser sintering:
+ Production of metallic components
+ Layer thickness between 20-60 µm
+ Several components can be printed in one operation
- Post-processing of the surface required
- Powder must be removed after printing
- Not all metal alloys printable
Possibilities of 3D printing
Designs of a component cannot be created arbitrarily, because they must also be producible with the available manufacturing method. Particularly in the case of machining production processes, special attention must be paid to these production-side requirements in order to keep manufacturing costs as low as possible. 3D printing significantly increases geometry flexibility. Contours, undercuts or cavities that were previously impossible to produce can now be realized through 3D printing without the usual manufacturing restrictions. The very high geometry flexibility associated with this new process also makes it possible to design components that are considerably lighter in some cases, which offers great potential for optimization, e.g. in components for applications in aircraft. With 3D printed components, the geometry follows the subsequent function, not vice versa. As a result, 3D printed components can be much better adapted to their later use than was previously the case with production-ready components. However, completely new approaches are required in the planning and design of additively manufactured components.
3D printing specifics and manufacturing challenges
However, in addition to all the benefits, additive manufacturing processes also present challenges and potential drawbacks.
- Certain geometries, especially curves and fillets, have a disadvantage in 3D printing due to the process. These have to be provided with the aid of supports so that the desired geometry can be achieved. The support structure must be removed after the part is finished, which requires an additional post-processing step. If the support structure is located in places that are difficult to access, e.g. in cavities, the removal of this support structure can be very time-consuming or even impossible. Design-wise, the need for support structures can be avoided, but this necessitates attention to these 3D printing-specific requirements for support load-compliant design during component design.
- Due to the layered structure of the component in 3D printing, a step-like structure of the component structure is created as a result of the process. This is accompanied by the fact that the surface qualities of additively manufactured components are many times poorer than those of conventionally manufactured workpieces. Layer thicknesses range between 20-60µm and more and thus determine the edge fracture structure of the additively generated surface.
- Likewise, in almost all cases, post-processing is required for the holes, threads and fits provided. Furthermore, the heat introduced to melt the material can lead to heat distortion in the component, which negatively affects the dimensional accuracy of the 3D printed component.
- The metal powder used also poses a safety risk. In addition to the highly detrimental effect on health caused by inhalation of the respirable fine particles, a dust explosion can occur if the dusts come into contact with an open fire. Thorough removal of the metal powder is therefore necessary, also to prevent excessive discharge of the still usable powder from the machine for purely economic reasons.
- Since the laser sintering process generates a great deal of heat in the component, the material becomes brittle. This is accompanied by a loss of toughness, which means that 3D printed components have disadvantages for certain load spectra compared to conventionally manufactured components.
Additive vs. subtractive manufacturing: Advantages and disadvantages
In the following, we have compared and tabulated the most important features of conventional, subtractive manufacturing and 3D printing. Basically, a precise examination of the advantages and disadvantages, as well as a coordinated design is always necessary in order to fully exploit the advantages of 3D printing.
Feature | Subtractive manufacturing | Additive manufacturing (3D-Print) |
Processing duration | + | -- |
Postprocessing | + | - |
Surface quality | + | -- |
Material consumption | -- | ++ |
Energy consumption | + | - |
Construction effort | + | - |
Geometry clearance | - | ++ |
Production costs | + | -- |
Meets the requirements in comparison: ++ much better; +better; o similar; - worse; -- much worse
Conclusion
3D printing is still in development, but is gradually and increasingly establishing itself in industrial, professional applications. In addition to some disadvantages and necessary reworking of 3D printed components, 3D printing offers a completely new flexibility in the design and manufacture of components. Grindaix GmbH has also taken advantage of this to be able to design cooling lubricant nozzles in a much more function-oriented way. The form follows the function, manufacturing restrictions are reduced and thus better, tailor-made components can be realized.
Would you like to equip your machine tool with flow- and application-optimized coolant nozzles? We are your partner - because we combine our know-how in the field of coolant supply in machine tools with professional flow simulation and thus achieve an optimal, application-oriented design of your coolant nozzles. For manufacturing, we cooperate with experienced 3D printing companies in the field of laser sintering. You can find some examples of our 3D printed nozzles here. If you are interested in an optimized (if necessary 3D-printed) coolant nozzle, just contact us! We are looking forward to your request.
