How to Design Functional Models for FFF Technology?Agnieszka
Additive technologies enable us to create functional elements in relatively short time, which can complement, for instance, production lines. The undoubted advantage of this approach is the ability to create the model in one production process (in one operation), which significantly reduces the production costs and speeds up the process of its implementation.
The right choice of material
A wide range of available materials allows the exact match of the material to the working conditions of the component made. For example, ABS will be perfect for creating static structural elements, not exposed to high vibrations of the entire system. Elements made of ASA can be used outdoors because they are resistant to weather conditions (UV radiation). In conditions with high frequency of mechanical vibrations of the system, it is best to use PA and PA with carbon fiber or glass fiber. When the component made is to be used in conditions with elevated temperature, it is recommended to make it from PEEK.
Designing CAD models
Apart from choosing the right materials for the conditions in which the final component will be used, it is important to properly design CAD models. To properly prepare models for 3D Printing, follow these 7 rules:
1. When designing a model take into account the plane it will be printed on .
2. Avoid designing the walls of the model suspended in the air and use chamfers that will eliminate the generation of supports.
3. Design cooperating elements with approx. 0.4 mm allowance.
4. Design the holes in the model according to the layer growth during printing in Z axis.
5. Design the minimum wall thickness, in multiples of the diameter of the printing nozzle – (for a standard nozzle 0.4 mm – the minimum wall thickness is successively: 0.4 mm, 0.8 mm, 1.6 mm).
6. Design overhangs with a 60 degree draft.
7. Consider the dimensions of the model and the size of the 3D Printer‘s working chamber.
Parameters selected during G-Code generation (program for the printer), which determine the physical features of the model, have a big influence on lifespan and correct work of printed element. Such parameters are: infill density, type of infill, wall thickness of the model, etc.
A good example of the use of functional models printed in FFF technology can be the SMC pneumatic motor and rotary table mounting project. The design of the CAD model has been prepared for the needs of its implementation in additive technology. The design of the model includes the mounting of the actuator, mounting of the limit switches with the possibility of their adjustment, holes enabling fixing the model on the line and holes for pneumatic joints.
Figure 1. Model of mounting pneumatic actuator by SMC.
Figure 2. Actuator mounting CAD model, designed for additive technologies.
Figure 3. Rotary table mounting CAD model, designed for additive technologies.
Figure 4. Rotary table CAD model, designed for additive technologies.
Figure 5. Ready models presented during FORMNEXT Fair in Frankfurt.