Gyu-Bong Lee

Formability of ZK60A Magnesium Alloy Determined by Compression and Backward Extrusion

Magnesium alloys have been in the spotlight due to their high specific strength and stiffness. In order to manufacture forged products with magnesium alloys, it is crucial to determine the dependence of the formability on processing conditions. In this study, the formability of ZK60A manufactured by a continuous casting was experimentally investigated by uniaxial compression and backward extrusion. Processing parameters such as temperature and compressing speed varied in experiments. The surface quality and internal defects of the deformed specimens were carefully inspected for comparison purposes. A damage criterion is employed to quantify the formability under these two different testing routes. Furthermore, our results were compared to the damage data of the similar material reported in the literature.

Energy Analysis of Micro-drilling Process Used to Manufacture Printed Circuit Boards

Energy savings are becoming a new focus in the industrial sector because of environmental concerns. In order to establish an energy-saving strategy for micro-drilling, it is necessary to consider all aspects of the drilling procedure, including the post-drilling process. This study analyzed micro-drills with diameters of 400 μm. Process parameters, such as the rotational speed of the spindle and in-feed, were controlled, and the energy consumption of each process was measured. Operators can use the results to make decisions on process parameters and whether to perform a de-burring process. Ultimately, an effective energy-saving strategy can be devised for micro-drilling.

Development for automatic control system

Agile and flexible manufacturing systems make it mandatory that control programs have features such as agility, flexibility and reusability to meet fast changing, customer demands. To cope with this, a task-oriented model of the control system provides control code, data mapping and generating PLC code according to assembly sequences. The model is defined with the unit functions which can describe the complex assembly process with function elements. Task-oriented model also means the assigning and combining of unit function to generate the PLC code for assembly process. The artificial intelligence method executes knowledge processing for generating the PLC program. This approach of task-oriented method supports the flexible programming with high level of reusability, expandability, modifiability, and productivity.

Measurement of Droplet Size and Distribution for Minimum Quantity Lubrication (MQL)

Cutting fluid in machining is important due to their role in reducing tool wear and improving surface finish. However, controlling the usage is imperative due to the ecological and/or economical and reasons. Minimum quantity lubrication (MQL) has recently emerged as a viable option to minimize the amount of fluid used in machining without sacrificing its lubrication and cooling in machining. This paper presents our effort to understand the parameters in the MQL process in order to expand its effectiveness in cutting operations. Although some literature regarding the influence of flow rates and nozzle directions is available, this information is insufficient. This paper studies three new parameters in the MQL process, namely the droplet size, the droplet size distribution, and the wetting angle. Confocal laser scanning microscopy (CSLM), wavelet filtering, and image processing algorithms were used to calculate the droplet geometry and distribution for various commercially available MQL oils. The wetting angles of the oils were measured by depositing oil droplets onto TiSiN and TiAIN coated inserts. The parameters studied are important to estimate the comparative performance of lubricant-coating pairs.

An auto-configuration of 4M group management using Wireless Sensor Networks for reconfigurable manufacturing system

The 1st tier of automotive manufacturers has faced to pressures about move, modify, updating tasks for manufacturing resources in production processes from demand response of production order sequence for motor company and process innovation purpose for productivity. For meets this requirements, it has to require absolutely lead time to re-wiring of physical interface for production equipment, needs for change existing program and test over again. For prepare this constraints, it needs studying an auto-configuration functions that build for both visibility and flexibility based on the 4M (Man, Machine, Material, Method) group management which is supports from WSN (Wireless Sensor Network) of the open embedded device called M2M (Machine to Machine) and major functions of middleware including point manager for real time device communication, real time data management, Standard API (Application Program Interface) and application template management. To be application system to RMS (Reconfigurable Manufacturing System) for rapidly response from various orders and model from motor company that is beginning to establishing the mapping of manufacturing resources of 4M using WSN.

Collaborative Engineering System Supporting Product Development Process

Since customer’s demand is various and product life cycle is getting shorter, many manufacturing company is trying to reduce product development time and cost. The processes of product development involve a large number of components and the interaction of multiple technologies. For the above reasons, companies make an effort to design product on collaborative environment. The various activities in a product development are highly distributed. This distributed nature of the activities implies that teams will be working in different place and technical environment. Thus at a given time, teams might work on the same product from different perspectives. This will require efficient communication amongst the various individuals and the various software tools that are used by them. Therefore, there is a need for collaborative system that can support distributed design such that participants from different background collaborate towards one common goal. IT (Information Technology) is the foundation for collaborative system. In this paper the development of an enterprise-specific collaboration-strategy including process oriented co-operations in product development will be presented. This strategy particularly comprises new customer-oriented functionalities, tools for supporting collaborative product development as well as a systematic support for an implementation of collaborative system.Copyright

Evaluation of Backstitch Tool Path Strategy for Stability and Productivity in Micro-Drilling

Micro-drilling with spacing intervals in the hundred micrometer range is an essential process, however suitable methods are lacking despite efforts to develop useful strategies for precision micro-drilling. For efficiency, printed circuit boards are stacked in several layers and drilled through simultaneously but the process results in misalignment of holes as observed between consecutive layers from top to bottom. The work herein proposes a new tool path strategy in comparison with conventional methods. Hole positioning, drilling thrust force, and duration time were measured and evaluated. This strategy can be utilized in micro-manufacturing process for improving machining stability and productivity.Copyright

Modification of Surface Properties for Industrial Ink-jet Printing

characteristics of silver inkjet printing were intensively investigated under control of surface energy and substrate temperature. A fluorocarbon (FC) film was spincoated on a polyimide (PI) substrate to obtain a hydrophobic surface, and an ultraviolet (UV)/ozone (O3) treatment was performed to control surface wettability of the FC film surface. To characterize the surface changes, we performed measurements of the static and dynamic contact angles and calculated surface energy by Wus harmonic mean model. In silver inkjet printing, the hydrophobic FC film could reduce the diameter of the printed droplets. Merging of deposited droplets was observed when the substrate was kept at room temperature. Substrate heating was effective in preventing the merging phenomenon among the deposited droplets, and in reducing the width of printed lines. The merging phenomenon of deposited droplets was prevented also by increasing the UV/O3 treatment time.

Inhomogeneous Chemical Composition of Semi-Continuously Casted ZK60A Billet

Applying continuous casting to magnesium alloys is one of the recent issues due to relatively less defects inside the as-cast billet. In this study, homogeneity in the chemical composition of a commercial continuously-casted ZK60A billet was investigated. Density distribution depending on the distance from the center of the billet was measured, and the difference in density was analyzed based on the measured chemical composition.

Development of an efficient management system of energy resources consumed in PCB manufacturing processes

Since energy comprises a meaningful share of total production cost due to its surged cost, manufacturing companies should strive to take energy issues into account when planning and managing production processes and facilities. Energy resources such as electrical power, water, steam, gas, etc. must be monitored and managed as any other traditional enterprise resources. The aim of this paper is to develop the ERM system for monitoring and management of energy resources consumed in manufacturing processes and for analysis of energy efficiency of those processes. The system was implemented in the post-drill cleaning process, one of the processes to produce PCBs. The amounts of electrical power consumed per hour during the process were estimated by means of the ERM system. It was shown through the experimental measurement using the system that the heat drying process is possible with a decrease of about 33% in the electrical power consumption.