Papers by Author: Sheng Jye Hwang

Abstract: A barrel heating system will be developed by using induction heating instead of current resistance heating. The experiment results showed the induction heating system can change successfully the current resistance heating system in heated the barrel of injection molding machine. A working coil coupled with magnetic concentrator bars was also considered. Finally, the uniformity of temperature distribution is compared between two barrel heating systems.

Abstract: There are more than 20 different types of current commercially available mandibular advancement devices (MAD). Although there are so many different types of MAD available in the market, these designs are often not flexible enough to be adjusted to fit these devices to all possible cases. The aim of this study was to design and develop a new type of mandibular advancement device which used friction effect to achieve mandibular forward, and ensure it would not slide back during sleeping. The new type of mandibular advancement device could be quickly adjusted, and had 3-degree of freedom. ANSYS software was used to simulate whether the new design was strong enough. From the simulation it was found that the new innovative design was reliable and easy to be used for obstructive sleep apnea patients.

Abstract: The Rapid Prototyping (R.P.) technology which is used in manufacturing a three-dimensional solid part is based on the layer forming method. Currently, the main streams of commercially available machines use the point or line forming method to create the solid part. A thin polymeric material layer is delivered by a roller or scraper to form a thin material layer for further layer forming. This process won’t be able to control the size of the forming part. In this paper, “Liquid Spray Process” is proposed to use a spray pen to spread a thin layer of polymeric material on the forming bed for further layer forming in a rapid prototyping system. It will decrease time and cost of the current R.P. machines by spreading proper size of thin forming bed. The setup of the system of the automatic spray pen, continuous material supply system, spray parameter settings and man-machine interface control system were discussed in this paper. Furthermore, the Taguchi Methods were applied to find the optimal spray forming parameters including height, velocity, acceleration, control air pressure, atomizing air pressure, fluid flow of spray, material pressure and speed of gear pump. Finally, the minimum uniform coating thickness could reach as low as 25 μm with “Liquid Spray Process” when the optimal parameters were used. The uniformity could be well maintained for both sprays in cross or in parallel directions to form an area of 120 mm × 150 mm with the optimal parameters.

Abstract: This research utilizes a 2D printer mechanism from a commercial available inkjet printer, combines with hardware and software to build up a new concept 3D printer. This 3D printer can receive printing information from personal computer, and setting the required layer thickness to stack those layers into a solid model. The largest build volume is 300x420x350 mm, print head resolution is as high as 1200x2400 dpi, and the life of printer head is longer than 12 weeks which is far longer than 4 weeks of Z Corp’s. There are many specifications are better than or equivalent to those of Z Corp’s Z-510 which is the state-of-art machine of this powder based rapid prototyping.

Abstract: In rapid prototyping (RP) technologies, curing of UV-curable photopolymers is mainly achieved by the application of laser scanning with limited fabrication speed. The dynamic masking approach can improve the fabrication speed; however, current researches and available systems cure photopolymers with visible light rather than UV light. In this research, we have attempted to develop a UV dynamic masking RP system by implementing digital micro-mirror device (DMD) from digital light processing (DLP) technology and TFT liquid crystal display (LCD) panel. A DLP projector was disassembled and the main components were then recombined to form a dynamic mask generator. Thus, this study has shown the feasibility of obtaining a UV dynamic masking RP system that may be integrated for a UV-curable material processing.

Abstract: In this paper, the geometry influence of reflectors for infrared rapid surface heating on micro-injection molding was studied. A three-dimension ray tracing combined with transient thermal simulation was used to evaluate the thermal condition of injection mold surface. Several kinds of reflectors were applied to study the heating ability of the infrared rapid surface heating system. A commercially available optical analysis program, TracePro, was used to simulate the infrared emission to the center of mold surface. Thermal module of a structure analysis software, ANSYS, was used to study the absorption and heat transfer of the infrared heating on the mold surface. Then, Taguchi method was adopted to find the close to optimal reflector for rapid surface heating of micro-injection molding.