In this paper, micro-structured polymer parts were efficiently and accurately fabricated by micro-injection molding using a micro-structured mold core machined by wire electrical discharge machining (WEDM). The objective was to realize low-cost mass production and manufacturing of micro-structured polymer products. The regular micro-structured mold core was manufactured by precise WEDM. The micro-structured polymer workpieces were rapidly fabricated by micro-injection molding and the effects of the micro-injection molding process parameters on replication rate and surface roughness of micro-structured polymers were systematically investigated and analyzed. It is shown that the micro-structured polymer can be rapidly and precisely fabricated by the proposed method. The experimental results show the minimum size machining error of the micro-structured mold core and the maximum replication rate of micro-formed polymer were 0.394% and 99.12%, respectively. Meanwhile, the optimal micro-injection molding parameters, namely, jet temperature, melt temperature, injection velocity, holding pressure and holding time were 195 °C, 210 °C, 40 mm/min, 7 Mpa and 5 s, respectively. The surface roughness Ra at the groove bottom and top of the micro-structured polymer workpieces achieved minimum values of 0.805 µm and 0.972 µm, respectively.

https://www.mdpi.com/2073-4360/11/10/1591/pdf

Efficient and Precise Micro-Injection Molding of Micro-Structured Polymer Parts Using Micro-Machined Mold Core by WEDM.

Nowadays miniaturization with precision is an important requirement in the field of medical devices and high-end applications. This work introduces the concept of 3D complex geometry fabrication in microscale using typical 2-Axis wire-cut electric discharge machine (WEDM). In this regard, the threaded profile micro-pin has been chosen in the present study. Synchronizing the workpiece rotating speed with feed rate along with a suitable depth of cut is the required condition for fabricating a screw. A separate attachment has been developed and used to rotate the workpiece at different speeds. Further, a CNC code has been generated to design the tool path with the required tool feed and depth of cut. Initially, turning operation has been performed which results in reduction in the tool diameter into the desired dimension along with the elimination of the eccentricity of the rotating rod. Consequently, the thread cutting operation has been accomplished with the adjusted set of parameters. Besides, the surface topography and material characteristics of the fabricated screw fin have also been observed based on scanning electron microscopic images and energy-dispersive X-ray analysis. Finally, the established process has been escalated further to fabricate screws of minimum possible dimension using the WEDM.

Concept development for fabricating threaded micro-pin using wire-EDM

The demand of micro-machining with a diameter ranging from microns to some hundred is rising gradually in the field of aerospace, biomaterials, electronics, and automobiles, due to its noteworthy applications and benefits in miniaturized merchandises and gadgets. µ-EDM is the well-known non-traditional method used for making micro-metallic holes with assorted benefits like its distinguishing non-contact feature and thermoelectric energy between the workpiece to be machined and the electrode to be used. μ-EDM is a modification of the traditional EDM, rendering an imperative function in the generation of micro-features on hard-to-machine materials. In recent years, both processes, i.e., EDM and μ-EDM, are used extensively for production of dies, mold making, cavities, and complex 3D structures. The micro-components are typically finished by hard-to-machine materials and hold multifaceted shaped micro-structures that required accuracy in the level of sub-micron machining. This chapter provides an overview and the theoretical study of the latest 10-year researches from 2009 to 2018 that used decision-making and nature-inspired techniques in optimizing machining parameters of μ-EDM and μ-WEDM processes.

Multi-response Optimization of Micro-EDM Processes: A State-of-the-Art Review

Inflatable soft microactuators typically consist of an elastic material with an internal void that can be inflated to generate a deformation A crucial feature of these actuators is the shape of ther inflatable void as it determines the bending motion Due to fabrication limitations, low complex void geometries are the de facto standard, severely restricting attainable motions This paper introduces wire electrical discharge grinding (WEDG) for shaping the inflatable void, increasing their complexity This approach enables the creation of new deformation patterns and functionalities The WEDG process is used to create various moulds to cast rubber microactuators These microactuators are fabricated through a bonding-free micromoulding process, which is highly sensitive to the accuracy of the mould The mould cavity (outside of the actuator) is defined by micromilling, whereas the mould insert (inner cavity of the actuator) is defined by WEDG The deformation patterns are evaluated with a multi-segment linear bending model The produced microactuators are also characterised and compared with respect to the morphology of the inner cavity All microactuators have a cylindrical shape with a length of 8 mm and a diameter of 08 mm Actuation tests at a maximum pressure of 50 kPa indicate that complex deformation patterns such as curling, differential bending or multi-points bending can be achieved

Shaping Soft Robotic Microactuators by Wire Electrical Discharge Grinding

In the paper, the result of the investigations associated with the WEDM (Wire Electrical Discharge Machining) of the ruled surfaces with considerable slopes of the faces to the part base normal has been presented. The earlier measurement of surfaces subjected to such machining revealed considerable accuracy loss of non-linear progress with the increase of the wire electrode inclination angle. The double-stage correction procedure was suggested for improving the accuracy of manufacturing for the ruled surfaces. In the first directional stage, the part was manufactured at the highest possible material removal rate and then it was measured on the co-ordinate measuring machine (CMM). The employed NC part program was obtained by using one of the selected set of the CAD/CAM systems. The result of the measurement was used for reconstruction of the ruled surface model so that the corrected NC program could be used for machining the part with the enhanced accuracy. Design of the postprocessor used in the CAM module was the important part of the applied procedure because of the expected benefit from the condition of transferrable tool path digital description (CLDATA) between different applied CAD/CAM systems. In the presented method, the authors utilized the mechanism of the postprocessor generation and modification available for particular CAD/CAM systems like NX v.10 and Creo Parametric v.3.

/pdf/the-postprocessor-mapping-for-making-wedm-operations-4up0n5ykpm.pdf

Chen Xiang

Papers

Complex Rotary Structures Machined by Micro-WEDM☆