Abstract
An electrochemical machining (ECM) process for microcavity fabrication with deionized water (DI-water) and an ECM polishing hybrid with alumina powder of 1.0 μm grains on a single micro-EDM machine are proposed. The process adopts tungsten carbide as tool electrode and M-333 tool steel as the mold material. It reveals that employing the 30 μm/min feed rate with 50 mA and 0.2 ms of pulse-width is suitable for DI-water electrochemical machining. The DI-water ECM process can achieve an excellent surface roughness at Ra 0.169 µm on a semispherical round cavity. Combining the ECM with hybrid polishing with the alumina powder can achieve a better profile for a much deeper cavity than pure electrolytic discharge machining. The hybrid ECM polishing can efficiently finish a micro square insert of 0.6 mm length at 64 μm depth. Such ECM milling can achieve an S-shaped microchannel of radius 1.0 mm and a slot of 1.0 × 0.5 mm2 with 110 μm depth, demonstrating its feasibility and the surface integrity with accurate profile and roughness of Ra 0.227 μm. This study provides a cost-effective scheme for micro mold fabrication with a conventional micro-EDM machine tool and an intuitive and convenient optional process. However, some micro-electrical discharges occurred due to the breakdown of insulation, which creates micro craters on the surface of the parts.
Highlights
Based on physical and chemical principles, various nontraditional machining processes, such as electrical discharge machining (EDM) and electrochemical machining (ECM), have been well developed and play active roles in precision production and microfabrication technology fields
Besides the inaccurate contour caused by tool wear problems, the machined surface by EDM remains a heat-affected zone, with recast layers, and even micro craters
Considering the cost-effective, environmentally friendly, mirror-like surface requirements and the absence of tool wear for high polishing precision, this study proposes to conduct electrochemical machining of microcavities with deionized water
Summary
Based on physical and chemical principles, various nontraditional machining processes, such as electrical discharge machining (EDM) and electrochemical machining (ECM), have been well developed and play active roles in precision production and microfabrication technology fields. The primary purposes of this research are (1) a low-cost ECM process for microfabricating microcavity in mold industries through environmentally friendly work fluid; (2) to develop an efficient hybrid forming and polishing technology for manufacturing the precise and surface-integrity miniature mold; (3) to develop an intuitive operation and convenient optional process on a conventional micro-EDM machine tool for the industrial practice. Considering the cost-effective, environmentally friendly, mirror-like surface requirements and the absence of tool wear for high polishing precision, this study proposes to conduct electrochemical machining of microcavities with deionized water. The typical polarization curve represents the relationship between anode potential and current density and provides the electrochemical characteristics of metal dissolution in ECM [9], especially for ECM polishing It is usually plotted as the potential versus the logarithm of the current density observed for a surface that undergoes passivation and the breakdown on the passivation layer. TThheepprrininccipipleleofotfhtehheyhbyribdriedleeclteroctlyrotilcyptioclipsohliinsghipnrgocpersoscaessssocaisastoecdiawteitdh waluitmh ianlaumpoiwnadpeorwisdteor fisabtorifcaabteritchaetetothoelttipoowltiitphweliethcterolepchtroorpethicordeetipcodseitpioonsiatinodn fianndishfinthisehmthaechminaicnhginsiunrgfsaucrefasicme suilmtaunletoaunseloyuwsliythwEitChMECreMacrteioanct.iAonc.hAarcahcatrearicstteircisfetiactuferaetuofresuocfhsuacnhealencetrloecpthrooprehtiocdreetpicosdietipoonspitriooncepsrsoicsetshsaitsgtlhuaetygpluaeryticplaerst,isculecsh, sauscahluams ainluamabinraasaibvreass,iavrees,suarsepesunsdpeednidnead liinquaidliqsuoildutsioonlumtioignramteigarnadteaarneddeapreosdietepdosointetod tohnetototohleetloecotlroeldeecturonddeerutnhdeeirnflthueeinncfeluoefnacne eolfecatnrieclfiecetlrdic. field
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