Papers by Author: Kuo Cheng Huang

Abstract: Thermal fracture-cutting technology (TFCT) for brittle materials has become the main technology for LCD glass substrate cutting to meet the low residual thermal stresses requirement. Based on the thermal weight function principle of fracture mechanics, this paper presents thermal weight function distributions for the mode-I and mode-II fracture model, and the fracture phenomenon under a variety of cutting paths, such as tilt crack, split crack, twist crack, and local buckling.

Abstract: A thermal fracture process applied to the brittle materials has become a foremost technology, and applied to cut the LCD glass substrate. One advantage of this process is that the cross-section of cut glass substrate will be smooth with low residual stress after thermal fracture processing. The multi-sphere mirror aims to repeatedly reflect the light energy within upper and lower mirror in order to enhance the laser beam absorption rate of glass under cutting. Moreover, with a proper design of multi-sphere mirror, the energy distribution of applied laser can provide an ideal thermal fracture condition to improve cutting speed of glass substrate. A novel reflective mirror with multi-sphere surface was developed and reported to transform the regular laser energy distribution toward the ideal one. Furthermore, the shape of multi-sphere mirror is optimized by Taguchi method so as to meet the surface requirement that can get the ideal energy distribution. This paper presents a series of simulation results and analysis results of multi-sphere mirror calculated by the TracePro opto-mechanical software.

Abstract: This paper presents an approach to utilize high precision pulsed Nd:YAG laser to fabricate a rough array-pattern on a soda-lime glass plate by a laser-induced backside writing (LIBW) process, and a laser-induced plasma assisted ablation (LIPAA) technique. The current study investigates the effect of process parameters such as single-shot laser exposure time and number of passes on the material removal rate. After depositing 695 nm thick Teflon thin film on the glass plate, the surface of the laser micro-machined template becomes hydrophobic. The surface roughness, annular groove profile and surface micrograph were measured by an atomic force microscope, a profilometer, and a scanning electron microscope, respectively. A uniform liquid droplet by the sessile drop method is generated on the hydrophobic template. Droplet characteristics, such as contacted angle, size, and shape, are measured with a surface tension analyzer and microscope. This work also discusses the relationship between the formed droplets and the process recipe of the micro-machined template. The proposed approach can apply to future for uniform lens array formation.

Abstract: This paper proposed a novel method to fabricate micro-cylindrical lens array (μ-CLA) by using wire electrical discharge machining (WEDM) and precision glass molding (PGM) technique. Micro slits fabricated on the surface of tungsten carbide mold material with outline dimensions from 0.3mm to 2.1mm, the width and depth of 1 mm. The PGM processing parameters including width of slits, molding temperature, molding force and stroke were discussed. Moreover, the characteristics of μ-CLA were measured by contact profilometer. In addition, the relationship between the dimensions of the slit on tungsten carbide mold and the characteristics of μ-CLA also discussed.

Abstract: Stainless steel and other ferrous metals are normally classified as not diamond turnable for the unacceptable tool wear caused by the thermal-chemical reaction between diamond and ferrous metals. In the present research, stainless steel specimens were plasma nitrided at a relatively low temperature (<450oC) to prevent the depletion of Cr content at the austenite matrix and to give a hardened layer where Fe atoms are bonded to nitrogen atom to form γ’-Fe4N. Diamond turning experiments were subsequently carried out under the following machining conditions: single crystal diamond tool, cutting speed up to 180 m/min, cut depth up to 5μm and light mineral oil as the cutting fluid. The results showed that, given the same machining conditions, while rapid tool wear and poor surface finish were obtained when turning the as-received stainless steel, surfaces with Ra better than 3nm and no obvious tool wear were achieved when turning the plasma nitrided specimens