1. Pin-plate micro assembly by integrating micro-EDM and Nd-YAG laser 指導老師：戴子堯 學生：駱宏明 International Journal of Machine Tools & Manufacture 42 1455 – 1464 Jing-Dae Huang This paper presents a novel technology that applies the principle of Molten-Separation Joint (MSJ) from the micro-part back to perform precise micro assembly This has been realized by using a hybrid process that integrates micro-EDM and Nd-YAG laser welding on a single machine to fabricate micro parts and complete precise micro assembly.

2. Outline Introduction Hybrid machine Results and discussion Conclusions

3. Introduction In those fields, a variety of techniques have been considerably developed, by using diverse forms of energy for fabricating micro parts, such as photochemical machining and electrochemical [3 – 8], mechanical machining [9], and electro-thermal machining [10 – 16]. Based on the characteristics of workpiece and product shape, one can choose an appropriate micromachining method.

4. Introduction Among electro-thermal methods, micro-EDM is a machining method using a free electrical discharge between an electrode and a workpiece to generate heat flow with high energy density, so that contact force and chatter vibration can be avoided during machining. Therefore, it is suitable for fabricating metal micro parts.

5. Introduction Micro assembly is a feasible method to make 3D micro metal parts. However, the first challenge is how precisely to position the micro parts assembled. Masuzawa et al. [16] (A Micro-EDM/Assembly System Unit for Microparts Fabrication)

6. Introduction Masuzawa et al. [16] has used a micro-EDM machine to assemble a micro pin/plate tool workstation, then the assembly process was completed by an ultrasonic vibration to produce ultrasonic bonding between the pin and the plate, each of which was made of different materials. Since the whole process was finished on the same machine, high positioning precision can be gained.

7. However, to complete the assembly, a twist was adopted to separate the micro pin at a necking. This would limit the aspect ratio and bonding strength of the product.

8. Hybrid machine In the work, a novel hybrid process to overcome the above stated problems is introduced here. An high aspect ratio can be easily attained.

9. Hybrid machine (A): the stereography for the hybrid machine. (B): the stereography for micro- EDM mechanism. (C): the configuration of top view for three laser beams.

10. Hybrid machine (A): the stereography for the hybrid machine. (B): the stereography for micro- EDM mechanism. (C): the configuration of top view for three laser beams.

11. Hybrid machine (A): the stereography for the hybrid machine. (B): the stereography for micro- EDM mechanism. (C): the configuration of top view for three laser beams.

12. Hybrid machine In the hybrid machine laser can be radiated 3 laser fiber optic beams. Because 3-laser optic beams simultaneously radiate around the pin in directions separated by 120

13. Results the tensile test for the case of the pin 200 μm in diameter

14. Results Since the tensile strength of the pin increases as its diameter increases, we can believe that cases where the pin ’ s diameter is less than 200 μm have a sufficiently high strength at the joint.

15. Results Since the tensile strength of the pin increases as its diameter increases, we can believe that cases where the pin ’ s diameter is less than 200 μm have a sufficiently high strength at the joint.

16. Conclusions High aspect ratio is easily attained: the aspect ratio of pin-plate part, length to diameter for micro pin, can attain about 30:1 The assembled strength using the laser fusion welding is stronger than other assembly methods

17. Conclusions The tensile test shows the failure position usually falls at the certain position of the assembled pin; that is, the joint strength is enough, subjected to the axis direction load. The hybrid machine combined micro-EDM and Nd-YAG is suitably applied to the precise micro assembly process.