Apply spray coating technology to liquid based rapid prototyping system

The RP (rapid prototyping) technology is a material additive process to build parts layer by layer automatically. The most challenge task of the process of the liquid based RP system is how to control the new added material with regard to the thickness and flatness to the surface of the working camper. The conventional liquid based RP system employs a special designed recoat or to scrape resin from one side of the tank to the other to ensure the surface flatness. The scraping procedure will bring extra resin out and a drawback of shear force to the working part. In order to overcome the drawback of the shear force, a supporting structure is necessary under the working part. In this research, spray coating technology has been applied to replace the role of recoator. In addition, there is no scraping process so it brings additional advantage of no shear force to the working part. Therefore, only a limited supporting structure is required. Come together with the use of spray coating technology, a dynamic slicing algorithm has been proposed. The conventional RP system is to slice the working part before the fabrication to keep a fixed and even layer thickness. On the other hand, the spray coating technology will not always come out with the same thickness during fabrication. It is necessary to compensate the projected thickness in every layer. The dynamic slicing algorithm is used to slice the working part during the fabrication process. The test results demonstrate the ability to add a new layer of resin as thin as to 10 mum. It also shows the potential to form fine features with a restricted supporting structure.