Advanced design for manufacturing processes

Arc welding, which is welding process using the heat of an arc as a heat source, is essential in the manufacturing field. due to the importance of production efficiency and light weight of manufactures. However, various by-products such as slag, heat tint, and oxide layer occur around the weld bead. It adversely affects the corrosion resistance and the coating quality of the product. For this reason, by-prodcut formed after arc welding should be removed to improve the performance.

Laser cleaning is a non-contact and eco-friendly technology based on laser ablation. This technology is mainly used to improve product quality such as corrosion removal, paint peeling, and by-product removal without directly affecting the base material.

            The polymer are not easily decomposed. The developments of eco-friendly materials are actively carried out due to environmental pollution of wastes, soil degradation, and leakage of endocrine disruptors. Poly Lactic Acid (PLA), the most widely used biodegradable polymer material, is produced by chemical method for fermenting the sugar and starch obtained from plants. 

            This study applies pulsed fiber laser to PLA, and observes the effect of laser parameter on the change of microstructure and chemical properties of weld part.

            Laser ablation plays an important role in the laser application for the processing of materials. The most important aspect of using laser for the ablation process over other processes is because heat conduction produced in the surface is being processed as well as less or no collateral damage happened due to shock waves during the process. 

            The major application of the laser ablation process is used to produce complex surface patterns or to alter microstructures in high precision processing. Laser ablation is affected by laser parameters such as wavelength, power, and pulse width. Furthermore, the interaction properties between the laser and the material can be controlled by laser parameters. Laser ablation occurs when sufficient energy is absorbed into the material surface to break the bond between atoms. When energy above the characteristic threshold is irradiated during laser-material interaction, ablation occurs on the surface. However, little craters are produced when laser energy is irradiated below the threshold. In addition, no surface changes occur due to physical, chemical, or reaction. 

            In laser parameters, the ablation threshold is defined as the minimum laser energy. It plays an important role because it greatly affects laser processing depending on various variables. The laser ablation threshold increases or decreases with laser parameters, and the resulting laser ablation results vary. To predict the laser ablation threshold, you need to adjust the number of largely irradiated pulses, and you can predict the threshold by measuring the crater size according to each pulse count.

            The aviation and railway industries are experienced with attached ice on metal surface in winter season. For example, freezing airfoil of airplane causes delay and the attached ice on railways causes derailment and slow operation. Also, the attached ice and water contacted on metal surface reduce metal’ residual life. 

            Laser Surface Treatment (LST) is proposed. This research objective is the fabrication for hydrophobic surface of metal using LST. Hierarchical structures are induced by laser surface treatment, and surface free energy on the irradiated surface is reduced.

To be updated