The strength of a 3D printed model is influenced by a number of factors, primarily the geometry/shape of the model, the printer on which the print is made and the temperature of the print, the type of material and the amount of outer contours and top/bottom layers and the degree of infill. Read the article and find out when to opt for 3D printing.
The first step to making a robust print is to properly prepare the model in customised software. In addition, it is a good idea to consult the geometry and design of the component with a printing expert to verify its durability, taking into account the wall thickness, type and percentage of print fill with material.
An important element that significantly improves the quality of prints is the use of a suitable 3D printer, preferably with a closed chamber that maintains a constant temperature throughout the printing process. This will ensure that the print does not cool down too quickly and that the layers have time to fuse together, ensuring the durability of the print. Printers with a closed and heated chamber ensure less shrinkage of the entire model and avoid warping, i.e. peeling off at the edges of the first layer of the model from a material with a higher shrinkage than the print platform It is easier to print the part with the correct dimensions. Maintaining the correct temperature inside the chamber will protect against overheating of the material and therefore increased fragility of the model.
Probably the most crucial element regarding the strength of 3D printing, is the type of filament chosen from which the model will be printed. The decision should take into account the following questions:
A customer comes in with a designed model, which is to be a prototype part, with an industrial application, exposure to large temperature fluctuations, including temperatures of over 200 degrees. In addition, the part will be exposed to pressure forces during operation.
The following materials have been proposed:
When making a choice, these two materials can be weighed against each other, taking cost into account, and assessing whether the purpose of the prototype is to check its shape and dimensional accuracy or whether the overriding goal is to verify the strength of the model.
A customer comes in with a model to be used as a production component in electronic devices. Dimensional accuracy, flexibility, 80 degree temperature are particularly important. No exposure to pressure force.
The following material is proposed:
TPU – a thermoplastic material, with high flexibility (withstands high mechanical stresses) and temperature resistance. It will easily fit in different places.
The customer requests a prototype housing for a sports camera or smartphone. PET-G has good mechanical properties and is strong and flexible, making it ideal for the production of housings for devices that require protection from impacts and shocks. Such a case will resist scratches and mechanical damage, while being flexible and easy to work with. PET-G also has a good level of light transmission, meaning that the enclosure will be transparent and will not affect image or signal quality.
Once you have decided on a filament, you need to choose a print temperature for it. You need to pay attention to the manufacturer’s requirements, as materials with the same name often have different temperatures for drying the material before printing and different temperatures for the printing itself. Remember to maintain the temperature throughout the printing process, so that the layers will bond permanently and the strength of the print will be high.
An important element when planning the printing of models is to choose the right printing direction. The strength depends on the orientation of the layers. The highest strength is given by printing horizontally, i.e. parallel to the print bench. When printing vertically, perpendicular to the print bench, the strength may be weaker. With complex model geometry, the direction should be selected individually, according to the design and the chosen filament. It is necessary to pay attention to the supports and the ease of their removal.
Increasing the number of outer contours has a greater impact on the strength of the 3D model than changing the infill, as the outer contours are the most stressed. Additional outer contours increase the contact area between layers and provide greater stability and resistance to crack propagation. Changing the infill, on the other hand, will affect the strength of the model less because the infill is applied inside the model and not on the outer layers. The infill has more of an effect on the mass and stiffness of the model than on its strength. However, for some applications, such as printing parts with a lot of holes or spaces, changing the infill may have a greater impact on strength. Using the layer grouping function, it is possible to set different degrees of infill in different parts of the print. This has less of an effect on the strength than if the print had less infill over the entire surface.
The thickness of the print layer affects the strength and appearance of the model. Thicker layers can reduce the quality of the print, but at the same time can increase the strength of the model.
Print speed affects the strength and quality of the print. Printing too fast can lead to imperfections, while printing too slow can increase print time. Ultimately, the optimum print speed will depend on many factors, such as the type of material, layer thickness, type of 3D printer, model design and complexity. Therefore, it is important to experiment with different print speeds to get the best results.
The strength of 3D printing, is also affected by post processing. It is particularly important to take care of the safe removal of supports. The best and most accurate method is to dissolve the supports using chemicals designed for this purpose. Removing supports with knives, files or unskilful sanding can adversely affect the surface of the entire model and cause it to crumble and eventually break. Sanding and polishing can remove thin layers of material, which can weaken the structure of the print and reduce its strength. Additionally, applying paint or varnish to the print can increase its weight, which can also affect its strength.
It is worth remembering that post-processing methods can be used to strengthen the model such as reinforcement with glue, resin or carbon fibre. This will increase the resistance to mechanical damage.