Abstract:

Objective Flexible and complex 3-D structure forming is one of the main difficulties of concern in the field of clothing 3D printing technology. The selective laser sintering (SLS) process and thermoplastic polyurethane (TPU) materials have obvious advantages in addressing this difficulty. However, there is a lack of more systematic research on the 3D printing clothing development process based on this technology combination. This study carry out an empirical research which combines case studies and summaries of universal problems to address this issue.
Method As the initial attempt, a digital model of a 3D printed corset was designed and generated by comprehensive usage of the soft-ware including DAZ 3D, Blender, CLO and Materialise Magics. Then, the study produced a physical model of a flexible 3D printed corset with wearability by using an EOS P700 3D printer and TPU powder material. Eventually, the development process of this case was designed and generated in detail, from which extracted a universal 3D printing clothing development process.
Results The produced flexible 3D printing corset was made of the TPU material with Shore hardness of 88A and has a maximum wall thickness of 4 mm, resulting in a clothing with good shaping ability as well as the expected flexibility, which contains complex 3-D structures such as layered, overhang and hollow for testing the capabilities of SLS-TPU technology in the forming of complex 3-D structures(Fig. 11). A rear central non through-body invisible zipper placket was used to enable the clothing to be put on and taken off(Fig. 7), which was divided into upper and lower parts with a waist division line and is manufactured separately, and assembled together with boss-groove structure and a sewing process by using 0.12 mm transparent nylon wire(Fig. 6, Fig. 8). The universal process of 3D printing clothing based on SLS process, TPU material and thin wall structure obtained through this study includes 5 major steps, which are digital 3-D base model modelling, digital 3D printing model modeling, digital 3D printing model data preparation, physical 3D printing model manufacturing, and physical 3D printing model post-processing, as well as the 20 sub-steps under them(Tab. 1). The fourth step was not discussed in detail because the work was carried out by a third party manufacturer.
Conclusion The study shows that the initial shape of the 3-D digital model, the fit between the hardness of the TPU material and the wall thickness of the model have a significant impact on the variable and flexible shape of the 3D printed clothing, and also demon-strates the feasibility of using the sewing process for piecing together 3D printed models of clothing. The study proposed a series of solutions for 5 key generic issues in this case development process, including 1) the initial shape setting of the digital clothing 3-D base model, 2) the setting of the clothing 3D printed model's wall thickness and material hardness, 3) the matching of the clothing 3D structure to the 3D printing process, 4) the design of the 3D printing clothing putting on and taking off method, and 5) the disassembly and assembly of the clothing 3D printing model. In the future, the various steps of the clothing 3D printing process involved in this study can be studied in more depth in terms of material performance, process technology, cost control and sustainability by using quantitative measurements and lateral comparisons.

Key words: cloth, 3D printing, additive manufacturing, thermoplastic polyurethane, selective laser sintering, thin-walled structure