3D Printing Support Material

3D printing supporting material [1] is used in the fused deposition modeling (FDM) 3D printing technology. During the printing process, parts of the suspended or hollow structures of the auxiliary products are formed, and the materials are removed after printing is complete. The working principle of FDM 3D printing technology [2] is that hot melt materials (ABS, PLA, wax, etc.) are processed into filaments, which are transported to the hot melt printing nozzle through a wire feeding mechanism. The filaments, or linear plastic materials, are heated to a molten state in the nozzle, and the nozzle moves along the shape profile and trajectory of the parts under computer control. The melted material is extruded and deposited in the desired position, then solidifies and forms, bonding with previously formed layers to create the product model, layer by layer. In the printing process, each layer is stacked on the previous layer, which plays a role in positioning and supporting the current layer. When the product has a suspended or hollow structure, some auxiliary structures – "supports" – must be designed to provide positioning and support, ensuring a smooth forming process.

Currently, there are three types of support materials and technologies:

The first is a strip-type framework material [3]. The same material as the product body is printed into a loose structure where support is needed. After printing, the supporting material is removed from the main material using physical methods (such as a knife or other tools). This method has drawbacks, including difficult operation, difficulty in removing the support material itself, and potential damage to the main material.

The second is dissolved support material [4]. This primarily uses water-soluble materials like polyvinyl alcohol, acrylic acid copolymers, and others [5]. After printing, the finished product is immersed in water, using the water-solubility of the support material to remove it. This method better protects the surface quality of the product. However, water-soluble materials often have poor cohesion with bulk materials, and a swelling process occurs before dissolution, which can sometimes damage the product. It has also been reported that HIPS [6] material can be dissolved in limonene, but the cost of using limonene is higher.

Thirdly, there are decomposed 3D printing support materials [7]. This method, reported in "Mechanical Engineering Materials" No. 5, 2018, involves immersing the printed parts in acidic liquids at a specific temperature. The supporting materials decompose into gases and are removed. This type of decomposition material uses polyformaldehyde (POM) as the base material, with other materials added. POM is a common engineering plastic with a low cost and good supporting effect. There is no effect on product appearance after decomposition. Furthermore, the decomposition properties of POM materials open up applications for FDM 3D printed products in fields such as EPC, indicating a promising future.

References

[1] Li, L; Sun, Q; Bellehumeur, C; Gu, P. Composite modeling and analysis for fabrication of FDM prototypes with local...Journal of Manufacturing Processes, 2002, 4(2), 129~141. [2] Dickens, PM. Research developments in rapid prototyping[J].Journal of Engineering Manufacturing, 1995, 209(3): 261~265. [3] Crump, S Scott. Make RP models in end-product material. Design Engineering, 2003,49(5):20. [4] Masood, SH; Song, WQ. Development of new metal/polymer materials for rapid tooling using Fused deposition modeling. Materials and Design,2004,25:587~594. [5] Singh, R. Some investigations for small-sized product fabrication with FDM for plastic components[J]. Rapid Prototyping Journal,2013,19(1):58-63. [6] Analysis of Advantages and Disadvantages of Soluble Supporting 3D Printing Materials. https://3dprint.ofweek.com/2016-10/ART-132102-8470-30059693.html [7] Li Tianyi, Ma Chao. Effect of parameters on catalytic decomposition rate of thermoplastic polyurethane modified polyformaldehyde plastics in hydrochloric acid [J]. Mechanical engineering materials, 2018, 42 (05): 59-62.