Unconventional Applications of Electrical Discharge Machining

电火花加工(EDM)是一种精密的材料去除过程，它利用在电介质液存在下，在刀具和工件电极之间产生的受控、快速的电火花放电产生的热量。传统上，电火花加工的应用领域指的是难加工材料的加工，因为材料去除的热机制不受工件材料的硬度和韧性的限制，而不是需要塑性变形的切割过程。电火花加工已进一步应用于具有尖角的内腔等几何特征的加工。该工艺还用于加工薄/易碎的工件，因为由于刀具和工件之间没有物理接触，相关的力相对可以忽略不计。**由于电火花加工中的材料去除需要在微观尺度上局部熔化和汽化，所产生的表面包括大量微观的、重叠的凹坑。因此，电火花加工是极少数能够产生正偏斜度表面的制造工艺之一。这意味着表面包括散布在相对较宽的山谷中的峰，使得高度分布向右倾斜，这使得表面对于将在拟议的研究中研究的新型应用具有理想的预置。EDM还提供了针对特定应用定制特征凹坑的大小和纵横比的灵活性，这些凹坑共同构成纹理。这提供了令人兴奋的前景，通过适当地调整脉冲参数，在相同的过程中实现甚至相互冲突的功能要求，例如减少或增强摩擦。**在上述背景下，拟议研究的目标主要是探索电火花加工的创新、非常规应用，其中材料去除本身并不是主要目的，而是实现特定功能属性的表面形貌工程的目的的一种手段。特别是，拟议的工作将涉及以下科学研究：(1)电火花织构在提供气泡成核位置方面的作用，以增强沸腾换热，并在发电和电子工业中的应用，(2)汽车活塞环的织构，以增强润滑油进入和保持，从而减少摩擦，从而提高发动机性能和燃料效率，(3)在金属生物医学植入物上赋予适当的纹理，以促进其与骨骼结构的整合，以及(4)使用电火花加工来制造防水、自清洁表面，在航空航天、海洋和汽车工业中的应用。这项研究将进一步研究电火花加工在加工模具表面以增强基材和涂层之间的附着力方面的应用，探索电火花加工织构对移动流体的阻力的影响，并研究通过设计电火花加工织构来增加表面牵引力的机理。

Electrical discharge machining (EDM) is a precision material removal process that utilizes the heat generated from controlled, rapid electrical spark discharges struck between the tool and workpiece electrodes, in the presence of a dielectric fluid. Traditionally, the application domain of EDM has referred to the machining of difficult-to-cut materials, as the thermal mechanism of material removal is not limited by the hardness and toughness of the workpiece material, in contrast to cutting processes that entail plastic deformation. EDM has further been applied in the machining of geometric features such as internal cavities with sharp corners. The process is also used to machine thin/fragile workpieces, on account of the associated forces being relatively negligible due to there being no physical contact between the tool and the workpiece.**As material removal in EDM entails localized melting and vaporization at the micro-scale, the generated surface comprises a large number of microscopic, overlapping craters. Accordingly, EDM is one of the very few manufacturing processes with the capability to generate surfaces with a positive skewness. This means that the surface comprises peaks interspersed among relatively wide valleys such that the height distribution is skewed to the right, which makes the surface ideally predisposed towards the novel applications that will be investigated in the proposed research. EDM further offers the flexibility to tailor the size and aspect ratio of the characteristic craters that collectively constitute the texture towards a specific application. This offers the exciting prospect of achieving even conflicting functional requirements, such as a reduction or enhancement of friction, in the same process by appropriately tuning the pulse parameters. **In the context above, the objective of the proposed research is primarily to explore innovative, unconventional applications of EDM wherein material removal is not the primary intent per se, but rather a means to the end of engineering the topography of a surface towards realizing a specific functional attribute. In particular, the proposed work will refer to scientific investigations into: (1) the role of an EDM texture in providing nucleation sites for bubbles towards enhancing boiling heat transfer, with applications in the power generation and electronics industries, (2) texturing of automotive piston rings so as to enhance lubricant ingress and retention for reducing friction towards enhanced engine performance and fuel efficiency, (3) imparting an appropriate texture on metallic biomedical implants with a view to facilitating their integration into the bone structure, and (4) the use of EDM for the fabrication of water-repellent, self-cleaning surfaces with applications in the aerospace, marine and automotive industries. The research will further examine the application of EDM in texturing tooling surfaces in order to enhance adhesion between the substrate and a coating, explore the effect of an EDM texture on the drag against a moving fluid, and investigate the mechanism by which an EDM texture could be engineered to increase surface traction.