In this paper, a total of 57 micro and nano scale hybrid manufacturing processes are reviewed. These processes are categorized in terms of process timing and process type. Process timing is one of the most important aspects of manufacturing, and three different process schemes — concurrent, main/assistive (M/S) separate, and main/main (M/M) separate — are considered. The process type is categorized as either geometrically additive or subtractive, and all hybrid processes are categorized into combinations of additive, subtractive, and assistive process. Features and advantages are described for each of these classifications. Machining is found to be the most common process for both micro and nano-scale hybrid manufacturing. Of micro scale hybrid manufacturing schemes, 74.4% use assistive processes as a secondary process because the main purpose of most micro scale hybrid manufacturing is to improve the quality of the process. In nano scale manufacturing, 61.5% of hybrid manufacturing schemes employ assistive processes, since these processes typically focus on the fabrication of parts that are difficult to fabricate using a single, existing process. Based on a summary of published work, future trends in hybrid manufacturing at the micro and nano scale are suggested.

https://link.springer.com/content/pdf/10.1007%2Fs40684-014-0012-5.pdf

Hybrid manufacturing in micro/nano scale: A Review

Electrochemical discharge machining (ECDM) is a hybrid non-conventional machining process, used to machine electrically conductive and non-conductive materials. It is a preferred process to fabricate micro scale features like micro holes, micro channels, microgrooves and 3-dimensional intricate shapes on variety of materials. In order to improve the efficacy of ECDM process, certain technical augmentations are provided with basic configuration of ECDM. These augmentations result in developments of ECDM process variants. Further, research community has developed ECDM based triplex hybrid methods for further process enrichment. This review article presents a comprehensive review of these recent developments in ECDM process, its variants and their triplex hybrid methods. The future research possibilities are identified and presented as research potentials.

Developments in electrochemical discharge machining: A review on electrochemical discharge machining, process variants and their hybrid methods

Micro-machining has attracted great attention as micro-components/products such as micro-displays, micro-sensors, micro-batteries, etc. are becoming established in all major areas of our daily life and can already been found across the broad spectrum of application areas especially in sectors such as automotive, aerospace, photonics, renewable energy and medical instruments. These micro-components/products are usually made of multi-materials (may include hard-to-machine materials) and possess complex shaped micro-structures but demand sub-micron machining accuracy. A number of micro-machining processes are therefore, needed to deliver such components/products. The paper reviews recent development of hybrid micro-machining processes which involve integration of various micro-machining processes with the purpose of improving machinability, geometrical accuracy, tool life, surface integrity, machining rate and reducing the process forces. Hybrid micro-machining processes are classified into two major categories namely, assisted and combined hybrid micro-machining techniques. The machining capability, advantages and disadvantages of the state-of-the-art hybrid micro-machining processes are characterized and assessed. Some case studies on integration of hybrid micro-machining with other micro-machining and assisted techniques are also introduced. Possible future efforts and developments in the field of hybrid micro-machining processes are also discussed.

/pdf/hybrid-micro-machining-processes-a-review-1vomg9kyzg.pdf

Hybrid micro-machining processes: a review

High aspect ratio micromachining of glass by electrochemical discharge machining (ECDM)

The mechanical properties of metals change temporarily or permanently under application of electric currents under deformation. This phenomenon is often referred to as electroplasticity. The electroplasticity of metals and their alloys has been investigated under various loading conditions including tensile, compressive, bending, and hardness tests. Electrically-assisted manufacturing (EAM) utilizes this electroplasticity in manufacturing processes. Due to its technical advantages such as enhanced formability and reduced springback, EAM is energy efficient with reduced process time. Recent developments in EAM include various bulk deformation and sheet metal forming processes. This paper summarizes previously reported electroplastic behaviors of various metals or metal alloys and recent EAM processes. In addition, contemporary EAM patents are briefly reviewed.

/pdf/a-review-of-electrically-assisted-manufacturing-3zvbz29y4m.pdf

A review of electrically-assisted manufacturing

Micro-electrochemical discharge machining (ECDM) was studied in order to improve the machining of 3D micro-structures of glass. To minimize structures and obtain good surface microstructures, the effects of the electrolyte, the pulse on/off-time ratio, the voltage, the feedrate, the rotational speed, and the electrolyte concentration in the drilling and milling processes were studied.In ECDM, voltage is applied to generate a gas film and sparks on a tool electrode; however, high voltage produces poor machining resolution. To obtain a stable gas film over the whole surface of the tool at a low voltage, a new mechanical contact detector, based on a loadcell, was used; the immersion depth of the tool electrode in the electrolyte was reduced as much as possible. In this study, various micro-structures less than 100 μm in size, such as O 60 μm micro-holes, a 10 μm-thin wall, and a 3D micro-structure were fabricated to demonstrate the potential for micro-machining of glass by ECDM.

Micro-structuring of glass with features less than 100 μm by electrochemical discharge machining

Micro electrochemical discharge machining (ECDM) is a well-known machining process that achieves 3D micro structures in glasstype material. However, a rough surface is the main disadvantage of this process. In the present work, a hybrid process of ECDM and micro grinding using polycrystalline diamond (PCD)tools is investigated. Micro structures in glass workpieces were machined by ECDM and then ground by PCD tools to improve the surface quality. Micro grinding by PCD tools is used to overcome the rough surfaces that are generated by sparks in ECDM. The characteristics of micro grinding, such as the surface roughness of the tool, depth of cut, and feedrate, using PCD tools for ECDM structures were investigated. It is experimentally shown that the grinding process under PCD tools reduces the surface roughness of ECDM structures from a few tens of a μm to 0.05 μm Ra, and the total machining time of the hybrid process is less than a third compared to that under a conventional grinding process.

Hybrid micromachining of glass using ECDM and micro grinding

Seven arc-melted and then annealed CoCrFeNiNbx (x = 0.3–0.6) alloys are experimentally and thermodynamically investigated in the present work. All the as-cast and 1000 °C annealed CoCrFeNiNbx alloys are composed of face-centered cubic (FCC) and C14 Laves phases. Nb content in the C14 phase stays at around 24.5 at.%, and the Liquid → FCC + C14 eutectic reaction occurred at around 10.8 at.% Nb in a narrow temperature range. It is found that the microstructure in the CoCrFeNiNbx alloys is dramatically affected by the cooling rate and annealing treatment. The C14 phase easily spheroidizes and coarsens under high temperature, which indicates that the interface energy between FCC and C14 is very large. Moreover, the solubility of Nb in the FCC phase decreases with decreasing temperature. After annealing at 800 °C, a needle-like nano Mg3Cd-type τ phase precipitates from the pro-eutectic FCC phase and increases alloy hardness for ~100 HV. This should be a method to strengthen alloys.

https://www.mdpi.com/2075-4701/12/5/756/pdf?version=1651158367

Xuan Doan Cao

Papers

Micro-structuring of glass with features less than 100 μm by electrochemical discharge machining

Hybrid micromachining of glass using ECDM and micro grinding

Eutectic Reaction and Microstructure Stability in CoCrFeNiNbx High-Entropy Alloys

Bond-slip behavior between high-strength steel tube and Ultra-high Performance Concrete

Factors Determining the Maximum Recovery Stress of the Ni47Ti44Nb9 Alloy During Constrained Heating