Effect of Conventional EDM Parameters on the Micromachined Surface Roughness and Fabrication of a Hot Embossing Master Microtool
TL;DR: In this paper, the effect of conventional electrical discharge machining (EDM) parameters for generating micrometer and submicrometer leveled surface roughness was discussed, and statistical models were developed.
Abstract: This article discusses the effect of conventional electrical discharge machining (EDM) parameters for generating micrometer and submicrometer leveled surface roughness. Fabrication of submillimeter-sized microstructure to use as a master microtool for replication of polymer microcomponents is also presented. Beryllium copper mold alloy was machined using very low values of three input parameters: discharge current, pulse-on time, and pulse-off time. The input parameters and measured surface roughness were analyzed, and statistical models were developed. The analysis showed that surface roughness increased with the increase of discharge current and pulse-on time. These models were applied to lower values of input parameters to achieve high surface finish. A hot embossing replication master with microchannel structure was produced using the optimized machining parameters with an average surface roughness of 0.60 µm. The replication master was tested with a prototype micro hot embossing machine where it fait...
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TL;DR: In this article, the authors present a review of the progress of micro hot embossing in terms of polymeric material behavior and corresponding apparatus, challenges and innovations in mold fabrication techniques, and industrial applications.
Abstract: Micro hot embossing of thermoplastic polymers is a promising process to fabricate high precision and high quality features in micro/nano scale. This technology has experienced more than 40 years development and has been partially applied in industrial production. Three modes of micro hot embossing including plate-to-plate, roll-to-plate and roll-to-roll have been successively developed to meet the increasing demand for large-area patterned polymeric films. This review surveys recent progress of micro hot embossing in terms of polymeric material behavior, embossing process and corresponding apparatus. Besides, challenges and innovations in mold fabrication techniques are comprehensively summarized and industrial applications are systematically cataloged as well. Finally, technical challenges and future trends are presented for micro hot embossing of thermoplastic polymers.
199 citations
TL;DR: In this paper, the design of a precise, flexible, and corrosion-resistant underwater rotary spindle has been introduced to generate cylindrical forms on hard, difficult-to-machine materials.
Abstract: Results of applying the wire Electrical Discharge Machining (EDM) process to generate precise cylindrical forms on hard, difficult-to-machine materials are presented. The design of a precise, flexible, and corrosion-resistant underwater rotary spindle is first introduced. A detailed spindle error analysis identifies the major sources of error at different frequency spectrum. The spindle has been added to a conventional two-axis wire EDM machine to enable the generation of free-form cylindrical geometries. The mathematical model for material removal rate of the free-form cylindrical wire EDM process is derived. Experiments were conducted to explore the maximum material removal rate for cylindrical and 2D wire EDM of carbide and brass work-materials. Compared to the conventional 2D wire EDM of the same work-material, higher maximum material removal rates may be achieved in the cylindrical wire EDM, possibly due to better debris flushing condition.
101 citations
TL;DR: In this article, the influence of machining parameters on surface roughness and material removal rate of high strength armor steel using wire cut electrical discharge machining (WEDM) was presented.
Abstract: This work presents the influence of machining parameters on surface roughness (SR) and material removal rate (MRR) of high strength armor steel using wire cut electrical discharge machining (WEDM). Tests have been carried out with six process parameters: pulse-on time, pulse-off time, wire feed, flushing pressure, spark voltage, and wire tension. Taguchi's technique has been employed for experimental investigation. Results show that pulse-on time, pulse-off time, and spark voltage are significant variables to MRR and surface roughness (SR). The confirmation experiments have also been conducted to validate the results obtained by the Taguchi technique.
92 citations
Cites methods from "Effect of Conventional EDM Paramete..."
...Ali [4] developed statistical models to evaluate the effect of input factors on SR using the design of experiment (DOE) approach....
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TL;DR: In this paper, the state of the art related to the usefulness of powder metallurgy (PM)processed electrodes in imparting desirable surface properties and modification of the machined surface.
Abstract: Electrical discharge machining (EDM) is a well-established machining option for processing hard materials with complex geometrical shapes which are extremely difficult-to-machine by conventional machining processes. These hard materials find applications where lower surface cracks, wear resistance, corrosion resistance, etc. are desirable surface properties. In recent years, research has been carried out to determine the possibility of employing electrode as feed stock material in an effort to produce significant surface alloying. These electrodes are generally produced through powder metallurgy (PM) technique in order to achieve necessary combination of operating characteristics. This paper reports state of art related to the usefulness of PM-processed electrodes in imparting desirable surface properties and modification of the machined surface. The final part of the paper outlines the trends for future EDM research using PM-processed electrodes.
91 citations
Cites background from "Effect of Conventional EDM Paramete..."
...referred to as microelectric discharge drilling [22–26], fabrication of a hot embossing master microtool [27, 28] machining of microshafts as small as 5 m in diameter, and complex three-dimensional (3D) microcavities [29]....
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TL;DR: In this paper, an attempt was made to modify the surface integrity of C-40 steel in electric discharge machining (EDM) by using WC-Cu powder metallurgy (P/M) green compact tools.
Abstract: Electric discharge machining (EDM) is an electrothermal process where recast layer on the machined surface and heat-affected (HAZ) zone just below the machined surface are common phenomena. Thus, the assessment of surface integrity in EDM is a very important task. In this study, an attempt was made to modify the surface integrity of C-40 steel in EDM. WC-Cu powder metallurgy (P/M) green compact tools were used so that the tool material could be transferred to the work surface and thereby the surface characteristics could be altered. WC was used as tool material because of its ability to produce a hard layer over the work surface. A detailed experimental study was performed. The effect of various process parameters on the surface characteristics were presented with the support of analyses such as material transfer rate (MTR), tool wear rate (TWR), surface roughness, optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray (EDX), x-ray diffraction (XRD), microhardness testing, etc. It...
74 citations
Cites background from "Effect of Conventional EDM Paramete..."
...Ali and Mohammad [5] discussed the effect of conventional EDM parameters for generating surface roughness of micrometer and sub-micrometer levels....
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References
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TL;DR: In this article, a CAD/CAM system was integrated with micro-EDM to generate 3D micro-cavities using a recently developed uniform wear method, and the feasibility of the approach is illustrated by generating complex macro cavities using conventional EDM with single simple shaped electrodes.
Abstract: It is necessary to integrate CAD/CAM systems with micro-EDM to generate tool paths when simple shaped tools are used to machine three-dimensional (3D) micro parts. Currently available CAD/CAM systems cannot be directly used because of the continuous tool electrode wear during machining. This paper proposes an approach to integrate CAD/CAM systems with micro-EDM while accounting for tool wear using a recently developed uniform wear method. This approach is verified by successfully generating very complex 3D micro cavities. Additionally, the feasibility of the approach is illustrated by generating complex macro cavities using conventional EDM with single simple shaped electrodes.
171 citations
"Effect of Conventional EDM Paramete..." refers methods in this paper
...Micromilling tool, microgear, micromold cavity, and other microcomponents were successfully fabricated using micro-EDM [11, 12]....
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TL;DR: In this article, the authors developed a milling tool for micro-cutting in tungsten carbide with CNC-controlled EDM machines and showed the potential of the machining tools with a diameter smaller then 100μm.
118 citations
"Effect of Conventional EDM Paramete..." refers background in this paper
...It resulted in about 100nm Ra surface roughness [9, 10]....
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TL;DR: In this paper, the design of a precise, flexible, and corrosion-resistant underwater rotary spindle has been introduced to generate cylindrical forms on hard, difficult-to-machine materials.
Abstract: Results of applying the wire Electrical Discharge Machining (EDM) process to generate precise cylindrical forms on hard, difficult-to-machine materials are presented. The design of a precise, flexible, and corrosion-resistant underwater rotary spindle is first introduced. A detailed spindle error analysis identifies the major sources of error at different frequency spectrum. The spindle has been added to a conventional two-axis wire EDM machine to enable the generation of free-form cylindrical geometries. The mathematical model for material removal rate of the free-form cylindrical wire EDM process is derived. Experiments were conducted to explore the maximum material removal rate for cylindrical and 2D wire EDM of carbide and brass work-materials. Compared to the conventional 2D wire EDM of the same work-material, higher maximum material removal rates may be achieved in the cylindrical wire EDM, possibly due to better debris flushing condition.
101 citations
TL;DR: In this article, the design of a precise, flexible, and corrosion-resistant underwater rotary spindle has been introduced to generate cylindrical forms on hard, difficult-to-machine materials.
Abstract: Results of applying the wire Electrical Discharge Machining (EDM) process to generate precise cylindrical forms on hard, difficult-to-machine materials are presented. The design of a precise, flexible, and corrosion-resistant underwater rotary spindle is first introduced. A detailed spindle error analysis identifies the major sources of error at different frequency spectrum. The spindle has been added to a conventional two-axis wire EDM machine to enable the generation of free-form cylindrical geometries. The mathematical model for material removal rate of the free-form cylindrical wire EDM process is derived. Experiments were conducted to explore the maximum material removal rate for cylindrical and 2D wire EDM of carbide and brass work-materials. Compared to the conventional 2D wire EDM of the same work-material, higher maximum material removal rates may be achieved in the cylindrical wire EDM, possibly due to better debris flushing condition.
100 citations
TL;DR: In this paper, a mathematical model for the arithmetic average surface roughness on the ideal surface of a cylindrical wire EDM workpiece is derived and the effects of wire feed rate and part rotational speed on the surface finish and roundness for brass and carbide work-materials at high material removal rates are investigated.
Abstract: This study investigates the surface integrity and roundness of parts created by the cylindrical wire EDM process. A mathematical model for the arithmetic average surface roughness on the ideal surface of a cylindrical wire EDM workpiece is first derived. Effects of wire feed rate and part rotational speed on the surface finish and roundness for brass and carbide work-materials at high material removal rates are investigated. The pulse on-time and wire feed rate are varied to explore the best possible surface finish and roundness achievable by the cylindrical wire EDM process. This study has demonstrated that, for carbide parts, an arithmetic average surface roughness and roundness as low as 0.68 and 1.7 mm, respectively, can be achieved. Surfaces of the cylindrical EDM parts were examined using Scanning Electron Microscopy (SEM) to identify the macro-ridges and craters on the surface. Cross-sections of the EDM parts are examined using the SEM to quantify the sub-surface recast layers and heat-affected zones under various process parameters. This study has demonstrated that the cylindrical wire EDM process parameters can be adjusted to achieve either high material removal rate or good surface integrity and roundness. [DOI: 10.1115/1.1475989]
95 citations