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Zawartość zarchiwizowana w dniu 2024-05-29

Rapid Manufactuting of Products by Improved 3D Printing

Final Report Summary - RAMA3DP (Rapid manufactuting of products by improved 3D printing)

The development of new products is an iterative process involving design and visualisation, building prototypes, testing and evaluation. This is usually quite expensive and time consuming, especially if unconventional or complex geometries are required. Worldwide there is a strong need for a rapid prototyping (RP) technique, which is able to produce prototypes, which have the technical specifications (integrity, accuracy and shape), appearance (colour, texture) and feel of the desired product. In addition, there is a strong need for rapid manufacturing (RM) of (complex) one-offs, e.g. teeth, and implants and small series, e.g. mock-ups for surgical practising, high-end tooling and technical parts. There is increasing need also for manufacturing processes which do not produce onerous waste materials.

The technical and scientific objectives of the RAMA3DP project were:

1. to determine the technical feasibility and optimal process parameters of the individual processing steps of the 3 DP prototyping/manufacturing technique. This comprises the determination of:
- suitable powder-binder combinations. The target is to be able to tune the density between 0.5 and 2.5 gm/cc, and the tensile strength to be greater then 30 Mpa;
- material specifications (particle size distribution, polarity, shape, etc.) and material processing conditions (temperature, pressure, etc.);
- suitable colouring agents and composition of the base colours (red-yellow-blue) in relation to the resulting colour intensity and colour resolution.

2. to determine the best way, i.e. process configuration, to prevent contamination of the print head(s). The target is to increase the lifespan of print heads by 500 %, from 40 hours to 200 hours and to increase the maximum operating speed of 5 m/min to 20 m/min.

3. To build a prototype of the to be developed 3 DP prototyping/manufacturing technique with the following preliminary specifications:
- reproducibility: > 98 %
- density: at least between 1 and 1.5 preferentially between 0.5 and 2.5 gm/cc;
- structural integrity/tensile strength: at least 30 MPa, preferentially > 50 MPa
- dimensional accuracy: < 0.2 mm in X,Y,Z direction;
- surface smoothness: < 50 um, preferentially < 20 um;
- speed: at least 10 m/min, preferentially > 20 m/min;
- lifespan of print head: at least 100 hours, preferentially > 200 hours;
- graphical resolution: at least 200 dpi, preferentially 300 dpi;
- colour intensity: at least 40 RA; preferentially 100 RA;
- colour resolution: at least 10 RGB; preferentially 100 RGB.

4. to determine the applicability of the developed 3 DP prototyping/manufacturing technique by development of at least 4 partner-specific (process and) product applications.

5. to increase the creativity of designers by the ability to develop more innovative products more rapidly and more vividly by using colour and texture/prints. It also increases the variety of products, which can be developed.

6. evaluation of the developed 3 DP proto-typing/manufacturing technique by pilot production of demonstrators and 'product' evaluation tests.

The realisation of the concept of the 3D printing process of functional plastic parts was split up into a materials and process study, a machine concept and a controlling software system. In parallel the first market study was performed to map potential markets and customers.
Based on the material processing work which was performed by partners, (powder and binder) and the use of a testing ma-chine mounted with a specific print head, some straightforward geometry were realised.

In the second year of the project, a useful gain in speed has been developed. Fluid is shown to be compatible with stable jetting properties in the selected printing system. Study proved that contamination of the printing heads appears to be a minor problem: there is no tendency of the selected powder to clog the head.

A variety of simple and complex geometries has been modelled on a 3D CAD system to create test files for the prototype RAMA3DP machine. Some tensile testpieces have been produced successfully on a testbed at TNO. Results to date are very encouraging.

After completion of the specs, the building of the main RAMA 3DP prototype machine has been started. Additional motion control software was identified and implemented by PTS. The original plan did not take extra software development for general machine management into account.

Due to delivery problems of the printheads, the assembly of the main prototype was delayed until after the project end date.

Therefore the testing of the additional software was postponed till after the complete machine has been assembled. This will take place in the months after completion of the CRAFT project. After this integration testing the machine still has to be completely tested on the performance handling complete 3D objects. In the current phase only rectangles and dogbones have been thoroughly tested.

The market potential is assessed (and quantified) based on recent data from Wohler's report, indicating good potential for the CRAFT apparatus. A patent application has been filed.

The technical and economical assessment of the production of 3DP rapid manufacturing machines will not be performed. It is too premature. Moreover, this activity falls out-side the scope of this research project.

The final achievements of the project were:
- a prototype 3D-printing machine except for the printheads and drivers that in principle is able to 'produce' various components and parts;
- the ability to design and develop client-specific 3DP rapid manufacturing systems which produces reproducible consistent plastic like end products (size 20x20x20cm) that come close to 70% of the mechanical strength and 98% of the accuracy of injection moulded (IM) parts;
- the know-how of the process and the products that can be made with the new 3DP technique;
- a process for the reliable manufacturing of coloured parts having targeted colour properties with incorporation of texture/bitmaps on models directly being printed with a high resolution;
- user-friendly software, which allows the handling of coloured 3D models and/or to add colour and texture information to colourless models.