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2012/07/18

元智大學機械系電化學精密加工.mpg



EMAG ECM GmbH (ECM/PECM) 精微電化學加工技術在未來各種細微加工應用中佔有極大的優勢。該技術之優點係在於其加工能力與材料硬度無關,且能加工出微細及形狀複雜之表面結構,經由該製程加工後之產品表面具有粗糙度佳、無殘留應力及無裂縫產生等優良特性,常應用於航太、光電半導體、醫療器材、綠色能源、模具等產業上,本次研討會中特別邀請國內外知名學者及專家,介紹於精微電化學領域內之各種加工技術,可應用於燃料電池雙極板、生物晶片、微流體動壓軸承、微噴嘴、次世次流體分配閥元件、模具等產品加工上,機會難得,精彩可期。PECM為精密電化學切削的工程公司,其領先的技術,已在精密電化學切削領域達到量產化的水準。供顧客PECM精密電化學切削生產技術和客制化的製程設備。


詳全文 元智大學機械系電化學精密加工.mpg-利豐非傳統加工科技館 www.li-fung.biz-新浪部落 http://blog.sina.com.tw/lifung/article.php?pbgid=24968&entryid=622135
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2012/07/18

超精密拋光

電解拋光(Electrolytic Polishing)
所謂電解拋光,即是將工件放置陽極,於電解液中通電,在適當操作參數下,使工件發生電解反應(亦稱反電鍍),工件表面而因電場集中效應而產生溶解作用,因而可達成工件表面平坦與光澤化之加工技術。電解拋光機制示意圖如圖(十五)所示:


圖(十五)電解拋光機制示意圖

電解拋光技術於1931年,由D.A.Jacquet發明採行。「電解拋光」技術可廣泛運用在半導體製程設備、化工、航太以及其他高精密等表面處理加工。

電解拋光應用範圍:
(1) 可處理銅、黃銅、鉛、鎳、鈷、鋅、鍚、鋁、不銹鋼、鐵、鎢等材料。
(2) 電解拋光技術廣泛應用於半導體/LCD等級閥件、管配件、接頭、IGS之表面處理。
(3) 電解拋光可達鏡面級光澤,拋光後產品表面可達Ra=0.2~0.5μm。
(4) 不銹鋼電解拋光表面可生成鈍化層,有效提昇抗腐蝕能力。


詳全文 超精密拋光-利豐非傳統加工科技館 www.li-fung.biz-新浪部落 http://blog.sina.com.tw/lifung/article.php?pbgid=24968&entryid=622131
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2011/10/11

what is uECM (micro electrochemical machining)?

what is uECM (micro electrochemical machining)?

Electrochemical machining is a method of removing material by an electro chemical process. It is often characterized as “reverse electroplating,” in that it removes material instead of adding it.

Basic functional diagram of ECM
Basic functional diagram of ECM 


A tool (cathode) is advanced into a workpiece (anode) while a conductive fluid (electrolyte) is injected to the area being machined. A constant dimension gap is left between the tool and workpiece, and, as electrons cross the gap material on the workpiece is dissolved in a process called anodic dissolution. The tool feed rate is the same as the rate of liquefaction of the material on the workpiece. As the desired shape is formed the electrolyte carries away the metal hydroxide formed in the process.


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2011/10/11

why uECM - micro electrochemical machining

why uECM - micro electrochemical machining


Products are becoming smaller, lighter and more compact, and standards and quality requirements are rising. Micro-machining is finding more applications in many products in the aerospace, automotive, medical device, jewelery and consumables industries. There are many forms of micro-machining processes such, as laser machining, electro-discharge machining (EDM), micro-milling and electro-chemical machining (ECM) to name a few. In many instances the SME’s are the driving force behind advance in these technologies.

Diagram of example feature dimensions
example of feature dimensions  

繼續閱讀
2011/03/04

ECM - Advantages and disadvantages

ECM - Advantages and disadvantages

The ECM process has many advantages as regards to other machining techniques. These can be divided in machine, material and product.

Machine advantages:
  • Low running and tooling costs.
  • Initial investment in tooling is high, but the recurring costs are low.
    • o?electrode wear.
Material advantages:
  • The hardness, toughness and thermal resistance do not effect the Material Removal Rate (MRR). For tooling the product it is also not important if the tooling occurs before or after a hardening step.
  • MRR is high, approximately 1,5 cm3/min at 1000 A DC.
  • MRR does not depend on the type of material.
    • Hard and tough alloys are equally quick machined as for instance Aluminium.
Product advantages:
  • The product is after tooling free from burrs.
  • Contact free tooling principle.
    • The process gets no thermal or physical tension in the product.
    • No upper layer deformation like in other machining techniques.
  • 3-Dimensional products can be tooled in one single step.
  • High surface qualities are feasible (Ra <0,05 µm) depending on the material.
  • High dimension accuracy is feasible.
  • Material tension which is released during the process, is being counterbalanced if possible.
  • Stainless steel is influenced in its upper layer by various machining techniques, by which local rust formation can occur. This does not happen with ECM.
  • With the application of ECM, it is possible to generate more freedom of design for the product.

繼續閱讀
2011/02/07

Electrochemical machining

Electrochemical machining (ECM) is a method of removing metal by an electrochemical process. It is normally used for mass production and is used for working extremely hard materials or materials that are difficult to machine using conventional methods.[1] Its use is limited to electrically conductive materials. ECM can cut small or odd-shaped angles, intricate contours or cavities in hard and exotic metals, such as titanium aluminides, Inconel, Waspaloy, and high nickel, cobalt, and rhenium alloys.[2] Both external and internal geometries can be machined.

ECM is often characterized as "reverse electroplating," in that it removes material instead of adding it.[2] It is similar in concept to electrical discharge machining (EDM) in that a high current is passed between an electrode and the part, through an electrolytic material removal process having a negatively charged electrode (cathode), a conductive fluid (electrolyte), and a conductive workpiece (anode); however, in ECM there is no tool wear.[1] The ECM cutting tool is guided along the desired path close to the work but without touching the piece. Unlike EDM, however, no sparks are created. High metal removal rates are possible with ECM, with no thermal or mechanical stresses being transferred to the part, and mirror surface finishes can be achieved.

In the ECM process, a cathode (tool) is advanced into an anode (workpiece). The pressurized electrolyte is injected at a set temperature to the area being cut. The feed rate is the same as the rate of "liquefication" of the material. The gap between the tool and the workpiece varies within 80-800 micrometers (.003 in. and .030 in.)[1] As electrons cross the gap, material from the workpiece is dissolved, as the tool forms the desired shape in the workpiece. The electrolytic fluid carries away the metal hydroxide formed in the process.[2]

As far back as 1929, an experimental ECM process was developed by W.Gussef, although it was 1959 before a commercial process was established by the Anocut Engineering Company. B.R. and J.I. Lazarenko are also credited with proposing the use of electrolysis for metal removal.[2]

Much research was done in the 1960s and 1970s, particularly in the gas turbine industry. The rise of EDM in the same period slowed ECM research in the west, although work continued behind the Iron Curtain. The original problems of poor dimensional accuracy and environmentally polluting waste have largely been overcome, although the process remains a niche technique.

The ECM process is most widely used to produce complicated shapes such as turbine blades with good surface finish in difficult to machine materials. It is also widely and effectively used as a deburring process.[2]

In deburring, ECM removes metal projections left from the machining process, and so dulls sharp edges. This process is fast and often more convenient than the conventional methods of deburring by hand or nontraditional machining processes.[1]


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2011/01/15

電化學始祖 -- 法拉第效應

法 拉 第

Michael Faraday

 

文:小罐子老師

「當我讀到您在科學上的重要發現時,我深深地感到遺憾,我過去的的歲月實在浪費在太無聊的事情上。」    

       --這封信寄自太平洋上的一個孤島—聖赫勒拿島。寄信的人是一個犯人,名叫拿破崙。

女皇付租金

法拉第在英國皇家學院的頂樓小屋裡,已經住了42年,雖那時他已經是舉世聞名的科學家,但是仍然一貧如洗,沒有自己的房子。退休當天,他和妻子,兩個老夫婦提著皮箱下樓,想到出了皇家學院大門,就要露宿街頭,心裡有些茫然。沒想到出了大門,眼前出現的是整齊的英國皇家儀隊,和維多利亞女皇。女皇對著這位貧窮但卻是當代最偉大的科學家說:「請搬到我所準備的皇家別墅吧!」法拉第拒絕了,因為他付不出房租,女皇說:「不用付租金。」法拉第說:「但是房子太大,我付不出維修費用。」女皇笑著說:「別擔心!我來付好了。」

和其他科學家比較起來,法拉第最偉大的地方,就是他不曉得自己有多偉大。一個真正受到後人尊敬的科學家,除了科學上的貢獻外;更需具備有高尚的人格、情操,就像之前我們提到的富蘭克林,而法拉第也正是如此。

這位第一部馬達發電機的發明者,同時在電磁、電機、化學、合金、土木工程等方面有重大貢獻的科學家,一輩子都在貧窮、被誤解、無子、喪失記憶的打擊中,卻活出快樂、堅強,甚至還不斷幫助許許多多的人,值得我們一起來看看他傳奇的一生……。

愛讀書的釘書匠

法拉第在1791年出生於英國,父親是一位鐵匠,健康情形很不好,收入僅夠一家的溫飽。法拉第的父母是以溫善勤儉聞名鄉里,教子有方,從來不因家中貧困而氣餒。他們很想把法拉第送進學校讀書,卻又沒有錢供應這項費用。而且,當時英國的階級地位非常明顯,人們一出生就註定他的社會階級;法拉第的父親是做工的人,所以法拉第也必須去做一名學徒。然而困苦的環境,沒有使法拉第一家人痛苦,反而使他們更緊密。在他們的心中,貧窮是上帝給的祝福,而不是詛咒

小學畢業後,法拉第就到雷伯先生的書店學習釘書,成為一名釘書匠。他常常利用客人還沒來拿訂好的書之前,趕快閱讀那本書,有時候裝訂剩的書,他也會留一本下來閱讀。這些書的範圍包括了:藝術、科學、礦物、植物、地下水道、橋樑建造、甚至於論愛爾蘭豬的關節炎等,各式各樣奇怪的內容。其中一本 以薩華茲博士 所著的《悟性的提升》提到的五個讀書方法,對法拉第影響很大,成為他一直奉行的治學方法:

第一、作個人的筆記

第二、持續的上課

第三、有讀書的同伴

第四、成立讀書會

第五、學習仔細觀察和精確的用字


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2011/01/03

ECM History

HISTORY

From machining technique to versatile ECM technique

Electrochemical Machining is a relatively old machining technique whose basis was laid way back in the 19th century. Michael Faraday, the greatest researcher of all time (1791-1867), discovered the principles of anodic metal machining.
faraday-picture
This discovery by Faraday has also laid the foundation for the better known electroplating and electro polishing techniques, commonly applied today in the industry worldwide.


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2010/12/13

ECM / PECM Examples 精密電化學/切削/成型/拋光實例

Photobucket Photobucket 

Photobucket Photobucket

Photobucket Photobucket 

Photobucket Photobucket Photobucket  Photobucket

精密電化學加工(PECM)和傳統電化學加工(ECM)的比較
傳統電化學加工
精密電化學加工
通常只應用在表面拋光,去毛邊和導角。 改良式電化學加工技術。
加工精度差。 更高的精密度2 - 5 µm。
定量加工距離1mm。 震動電極進行切削進給 50Hz。
無法作精微成型或精密加工
可變加工間距10-400 µm。
因電解液使用不同,需考量環保問題。 最大加工電流可達8000A。
  可應用於精微成型。
  能加工複雜外形,不生毛屑。
  電解液無環保問題。
 
精密電化學加工(PECM)和放電加工(EDM)的比較
放電加工
精密電化學加工
工作溫度 1,500 to 2,500°C (造成微小裂縫)。 工作溫度 20 - 50°C。
加工伴生的急熱、急冷會發生加工變質層(硬化層)(需要二次加工: 表面拋光)。 全無加工硬化層不會發生裂紋,無須二次加工。
電極與被加工物以某種比例損耗,可用電極低消耗的加工條件,但此條件會使其它特性劣化。 電極不會損耗,可以重覆加工(陽極融解現象,工件和電極沒有接觸)。
依電極用金屬而有消耗差,加工條件因材質而變化
粗加工表面粗糙度為Ra ≤ 0,5 µm。
加工速度慢。 細加工可達到鏡面。
加工成本高。 平均加工速度0,1 - 0,8 mm/min,比EDM快5-10倍
  加工精密度可達2 - 5 µm。
  電能加工複雜外形,不生毛屑。
   
高溫製程會造成許多缺點 ! 低溫製程有許多優點!
 
ECM/PECM Technology 技術優勢
使用PECM製程工具電極不會造成損耗。   只要一個電極可以重覆製造完全相同的產品。
不會有熱應力殘留,不會產生氧化層,不須要二次加工。
低溫製程,不會影响材料本質。    ▲不會影響材料本質和結構。    ▲可以延長工件壽命。
一般製程的表面粗糙度品質Ra ≤ 0,5 µm, 取決於電極製作的表面品質。
可以作鏡面加工。
高效率加工製程,因材料不同加工速度為 0.1 – 0.8 mm/min。
理想的電極材料為黃銅,但是其它導電材料都是可以作為電極。例如,紅銅,Preferred material for electrodes is brass, but also other conducting materials are possible e.g. copper,高品質的鋼,和石墨等等‧‧‧。
總而言之,ECM/PECM Technology 總合了EDM和ECM的優點,減少由這兩種特殊加工技術的缺點。更重要的是,使用者必須衡量傳統機械加工和特殊機械加工的特點為您生產的產品作最佳的選擇。
 
製程參數
  • 電壓—低電壓加工精度高。
  • 電解液種類—和工件材料相關。
  • 電解液濃度—和工件材料相關。
  • 溫度—溫度高電解液阻抗將降低。
  • 進給速度—將決定平衡間隙的大小。
  • 間隙—影響加工電流大小和加工精度。
 
ECM/PECM 精密電化學切削應用範圍
依功能分類
電解開孔,如輪機翼冷卻孔。
電解圓割加工,如曲孔。
電解微小孔加工。
精微成型。
電解切穿,如深孔或盲孔加工。
凹部加工(cavity sinking)。
電解成型 (shaping), 如曲面加工。
電解複印。
電解除屑加工,如去毛邊導角‧‧。
精密電化學加工的應用主要以傳統方式不易完成的加工為主,有以下幾個方向:
內齒輪加工。
花鍵孔加工。
渦輪葉片加工。
一體成形輪葉加工。
高消耗性模具,如鍛造模, 玻璃模, 壓鑄模等…。
燃料電池極板。
精密零配件。
精密醫療器材。
精密齒輪。


繼續閱讀
2010/12/12

Advanced Manufacturing: A different twist to electrochemical

ECM, or electrochemical machining, is considered a form of nonconventional metalcutting because it machines and deburrs parts without the cutting tool touching the workpiece. The advantage: No thermal or mechanical stresses are transferred to parts. However, traditional ECM cannot hold tolerances better than thousands of an inch. Fortunately, a process called precision electrochemical machining (PEM) from PEM Technologies, Natrona Heights, Pa., advances ECM, using a pulsed dc current and an oscillating cathode. PEM can machine hard and exotic alloys such as Hasteloy and Nitinol to less than a thousandth of an inch and produce fine features and small edge radii. It can also handle roughing and finishing in one operation, producing surface finishes down to 0.05 micron Ra.

Recall that ECM is often described as “reverse electroplating” because it removes material instead of adding it. The method works like this: The workpiece (anode) and tool (cathode) are exposed to electrolyte (a salt solution), which conducts electricity. As the tool moves towards the workpiece, the dc circuit closes and current flows. This dissolves the anode electrolytically, with the amount of material removed determined by tool shape and placement. The rate at which metal is removed is a function of current (I) × time (T), and is approximately inversely proportional to the distance between electrodes.


繼續閱讀
2010/12/12

Electrochemical machining

Authors: Meleka, A. H.; Glew, D. A.

Source: International Metals Reviews, Volume 22, 1977 , pp. 229-252(24)

Publisher: Maney Publishing


Abstract:

The history of electrochemical machining (ECM) is outlined, beginning with the basic 1929 patent of Gusseff, an outstanding visionary invention which recognized quite accurately the operating features of the ECM process. Early practical developments are described, leading to full commercial exploitation by Anocut in the 1960s. Recent specialized drilling applications in the aerospace industry are described, bringing the history up to date. The fundamental dynamics of the process are presented for plane-parallel gap conditions leading to the general analysis suitable for cathode tool design. The electrochemistry of the process is outlined, including the mechanisms of metal dissolution, their behaviour patterns, and their relationship with the Jacquet electropolishing curve. The machining rate limiting factors, including the rate of oxide film formation, are analysed. The effect of electrolyte acidity is examined, as is also the role of hydrogen ions in promoting breakdown of oxide films permitting higher machining rates. The nature of surfaces produced by ECM under various conditions is described, together with the resultant effect on mechanical properties. The ECM plant and its constituent units, including power supply feed systems and electrolyte handling equipment, are described, and the basic ECM operations such as shaping, drilling, turning, deburring, and grinding are considered. The review is concluded by outlining application experience and economics of the process in its practical realization in an industrial setting. A section is devoted to the prediction of possible future trends, and to those application aspects which would benefit from further research. Novel approaches to machine-tool design are suggested, aimed at higher plant utilization.

Document Type: Research Article

Publication date: 1977-01-01


繼續閱讀
2010/12/12

Electrochemical Grinding / ECG

Surface Treatments – Electrochemical Grinding

Electrochemical grinding, or ECG, is a variation of ECM and popular surface treatment that combines electrolytic activity with physical removal of material by means of charged grinding wheels. ECG can machine very smooth edges, without the burrs, caused by mechanical grinding tools, which require further machining. Like ECM, electrochemical grinding generates little or no heat that can distort delicate components.

The basic components of the process are a conductive grinding wheel, typically made of a matrix of copper, abrasive and resin, a tank that holds an electrolytic solution, and a direct current power source.


繼續閱讀
2010/12/12

Electroforming Technology: An Advanced Manufacturing Process

By Dr Thoguluva Raghavan Vijayaram PhD

Senior Lecturer, Department of Manufacturing Process and System, 
Faculty of Manufacturing Engineering, 
UTeM 
Universiti Teknikal Malaysia, Melaka Ayer Keroh, 75450 Melaka Malaysia. 
Email: thoguluva@utem.edu.my

Electroforming technology is a highly specialized process for fabricating a metal part by electro deposition in a plating bath over a base form or mandrel which is subsequently removed. Metal is electrodeposited on a mandrel, also called as a mold or matrix, which is the removed. Thus, the coating itself becomes the product. The electroforming process is particularly suitable to produce intricate parts such as molds, dies, waveguides, nozzles, and bellows made of nickel, copper, gold, and silver. This article discusses about the process description of electroforming technology, advantages, and its major engineering applications.

A variation of electroplating process is electroforming technology, which actually is a metal fabrication process. Both simple and complex shapes can be produced by electroforming, with wall thicknesses as small as 0.025 mm. Parts may weigh from a few grams to as much as 270 kg. Production rates can be increased through the use of multiple mandrels. Mandrels are made from a variety of materials like metallic zinc or aluminium or non metallic, which can be made electrically conductive with the proper coatings. It should be able to be physically removed without damaging the electroformed part. They may also be made of low-melting alloys, wax, or plastics, which can be melted away or dissolved with suitable chemicals. 
Electroformed metal is extremely pure, with superior properties over wrought metal due to its refined crystal structure. Multiple layers of electroformed metal can be molecularly bonded together, or to different substrate materials to produce complex structures with "grown-on" flanges and bosses.

Electroforming Diagram
Figure-1 Electroforming process

 

Figure-1 shown above explains the principle of electroforming process. The positively charged electroformed metal source (anode) at the left is broken down (ionized) in the copper electrolyte solution and is attracted to the negative charged mandrel (cathode). Build-up is achieved over all mandrel surfaces at an approximate deposition rate of .001 inch per hour.


繼續閱讀
2010/12/12

The Role of Electrochemical Machining (ECM) in Industrial Me

By
Dr Thoguluva Raghavan Vijayaram
BE (Mechanical Engineering, Madurai Kamaraj University, India),
ME (Metallurgical Engineering, Bharathiyar University, India),
PhD (Mechanical Engineering, Universiti Putra Malaysia, Malaysia),
Rector Grant Researcher in Metallurgy (Genoa University, Italy),
Chartered Engineer (M123412-3, IIE, Calcutta, India)
MIIF, MISTE, MIIPE, MIE (Calcutta, India)
Senior Lecturer in Manufacturing Engineering and Researcher in Metallurgy,
Department of Manufacturing Process and System, Faculty of Manufacturing Engineering, UTeM, Universiti Teknikal Malaysia Melaka, Ayer Keroh, 75450 Melaka, Malaysia.
E-mail: thoguluva@utem.edu.my

Electrochemical Machining (ECM) is one of the newest and most useful machining process of metal removal by the controlled dissolution of the anode of an electrolytic cell. This process is particularly suited to metals and alloys which are difficult or impossible to machine by mechanical machining. The working principle is based on Michael Faraday’s classical laws of electrolysis, requiring basically the two electrodes, an electrolyte, a gap and a source of D.C. power of sufficient capacity. ECM is basically the reverse of electroplating operation. Almost any conducting material can be machined by this method. Non conducting materials cannot be machined. A schematic sketch of the ECM process is shown in Figure-1.

rns5
Figure-1 Electrochemical Machining

In the actual process, the cathode is tool-shaped, more or less like the mirror image of the finished work piece. The work piece is connected to the positive supply. The tool or cathode, connected to the negative terminal, is advanced towards the anode (work piece) through the electrolyte that completes the electrical circuit between the anode and cathode. Metal is then removed from the work piece through electrical action and the cathode (tool) shape is reproduced on the work piece. The electrolyte bath is pumped at high pressure through the gap between the work piece and the tool and must be circulated at a rate sufficiently high to conduct current between them and carry heat. The electrolysis process that takes place at the cathode liberates hydroxyl ions (negatively charged) and free hydrogen. The hydroxyl ions combine with the metal ions of the anode to form insoluble metal hydroxides and the material is thus removed from the anode. This process continues and the cathode (tool) reproduces its shape in the work piece (anode). The tool does not contact the work piece producing no direct friction and therefore does not wear and no heat buildup occurs. Figure-2 shows a typical set-up of ECM process. Some of the important ECM elements are electrolyte, cathode tool, anode work piece, and D.C.power supply.

aytya
Figure-2 Scheme of ECM

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2010/12/12

How to Design and Manufacture an ECM machine



歡迎來到利豐行的世界,首先恭喜您來到這接受新的資訊讓產業更有競爭力,我們是提供精密表面處理的代理商,應對廠商高品質的表面處理需求,我們可以協助廠商滿足您對產業的不同要求,我們有能力達到非常卓越的表面處理品質,這是現有相關技術無法比擬的,表面處理技術皆集中於精密研磨,拋光, VTD PVD工具鍍膜, 光學鍍膜 optical coating, 金屬濺鍍 metallization, absolute chemie 精密CVD/PVD退鍍工藝EMAG Precision Electrochemical Machining 精密電化學加工技術(ECM / PECM)取代放電加工), EMAG 硬車削/乾式車削 hard turning, Koepfer 滾齒(齒輪加工製造) 技術, Reinecker, KARSTENS 內外圓研磨外圓+內圓曲面磨削, Naxos-Union軸研磨, 凸輪軸, KOPP非圓研磨, SW中心加工機, EMAG 雷射焊接, 自動化設備. oelheld 超高性能研磨切削油/EDM 放電加工液等我們成功的滿足了各行各業的要求,包括:精密需求高的軸承盒、射出成型的模具、高壓空氣閥、航太零配件、超高硬度的切削刀具、醫療配件及汽車用精密五金等等。我們的產品涵蓋了從桌上型到工業級的生產設備;從微細零配件到大型五金配件;從小型生產到大型量產;從半自動到全自動整合;我們的技術可提供您連續生產的效能,我們整體的服務及卓越的技術,恭迎您親自體驗.


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2010/12/12

Manufacturing Processes - ECM Electrochemical Machining Proc

Electrochemical Machining ECM

Electrochemical Machining fits in the category of machining as a manufacturing process. It involves removal of material from a workpiece using electrolysis. This is achieved by connecting the workpiece and the electrode to an electrical power supply. Similar to electrical discharge machining the material for this process to work has to be electrically conductive, but unlike electrical discharge machining the workpiece and electrode are immersed in an electrolyte fluid as opposed to a dielectric fluid.

Electrochemical Machining Advantages

The main advantage of electrochemical machining is that it can be used to machine extremely hard materials with no stressing. This is due to the absence of physical contact and heat. You will notice that there are many similarities between electrochemical machining ECM and electrical discharge machining EDM and consequently the advantages for both are also very similar, but ECM does have some distinct advantages over EDM.


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2010/12/12

Electrochemical Machining (ECM) is a cost-effective machinin

Electrochemical Machining (ECM)

Electrochemical Machining (ECM) is a rapid, cost-effective machining process that eliminates heat and mechanical stress. ECM is a deplating process that utilizes the principle of electrolysis. The ECM tool (cathode) is positioned close to the work piece (anode) and a low-voltage, high-amperage direct current is passed between the two via an electrolyte. Material is removed by anodic dissolution and then carried away by the electrolyte. Two-dimensional tolerances can be held to ±0.001 inches, three-dimensional tolerances can be held to ±0.002 inches, and 5 – 15 µ inch Ra surface finishes are achieved in a single pass. Barber-Nichols routinely machines turbine blisks, axisymmetric turbine nozzles, and various components with internal helical splines for the aerospace, energy, and medical equipment industries. The following features lend themselves effectively to ECM:

  • Internal Shaping (a.k.a. Plunge Holes)
    • Polygon Shaped Holes
    • High Length to Diameter Ratio Holes
    • Deep Narrow Grooves
    • Internal Helical Splines
  • External Shaping & Trepanning
  • Surfacing of Extremely Hard, Thin, and/or Easily Deformed Work Pieces

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2010/12/12

Electrochemical Machining

Electrochemical machining (ECM) is a method of creating metal shapes by removing metal using an electrochemical process. A direct current with high density and low voltage is passed between a workpiece (the anode) and a pre-shaped tool (the cathode). At the anodic workpiece surface, metal is dissolved and thus the tool shape is copied into the workpiece. 

Electrochemical machining creates components that are not subject to either thermal or mechanical stress and brittle material can be machined easily as there is no contact between the tool and workpiece. Electrochemical machining can create normal and delicate 3D shapes. Some example of parts that are made using electrochemical machining include dies, molds, turbine and compressor blades, cavities, holes, slots, etc. Electrochemical machining can process most types of conducting materials and alloys. Custom tooling is required in the negative of the desired part shape. 

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2010/12/12

Electrochemistry Encyclopedia

Electrochemistry Encyclopedia

(http://electrochem.cwru.edu/encycl/)

 


 

ELECTROCHEMICAL MACHINING (ECM)

Joseph McGeough
Institute for Integrated Micro and Nano Systems
University of Edinburgh
Edinburgh, EH9 3JL, United Kingdom

(July, 2005)

Michael Faraday early metallurgic researches, from 1818 to 1824, anticipated the developments which have led to widespread use today of alloy steels. Much effort has been expended to improve their performance for their service as cutting tools in machining. The aim has always been to yield higher rates of machining and to tackle recently developed harder materials on the principle that the tool material must be harder than the workpiece which is to be machined. Much progress has been made; however, in recent years some alloys, which are exceedingly difficult to machine by the conventional methods, have been produced to meet a demand for very high-strength, heat resistant materials. Moreover, these new materials often have to take a complex shape. A search has had to be made for alternative methods of machining since the evolution of suitable tooling has not kept pace with these advances.

Electrochemical machining (ECM) has been developed initially to machine these hard to machine alloys, although any metal can so be machined. ECM is an electrolytic process and its basis is the phenomenon of electrolysis, whose laws were established by Faraday in 1833. The first significant developments occurred in the 1950s, when ECM was investigated as a method for shaping high strength alloys. As of the 1990s, ECM is employed in many ways, for example, by automotive, offshore petroleum, and medical engineering industries, as well as by aerospace firms, which are its principal user.

Metal removal is achieved by electrochemical dissolution of an anodically polarized workpiece which is one part of an electrolytic cell in ECM. Hard metals can be shaped electrolytically by using ECM and the rate of machining does not depend on their hardness. The tool electrode used in the process does not wear, and therefore soft metals can be used as tools to form shapes on harder workpieces, unlike conventional machining methods. The process is used to smooth surfaces, drill holes, form complex shapes, and remove fatigue cracks in steel structures. Its combination with other techniques yields fresh applications in diverse industries. Recent advances lie in computer-aided tool design, and the use of pulsed power, which has led to greater accuracy for ECM-produced components.

Theoretical background

Since electrolysis is the basis of ECM, it must be understood before going further through the characteristics and other details of the process.

 Electrolysis

Electrolysis
Fig. 1. Electrolysis of copper sulphate solution.
Electrolysis is the name given to the chemical process which occurs, for example, when an electric current is passed between twoconductors dipped into a liquid solution. A typical example is that of two copper wires connected to a source of direct current and immersed in a solution of copper sulphate in water, as shown in Figure 1. An ammeter, placed in the circuit, will register a flow of current; from this indication, the electric circuit can be deduced to be complete. A significant conclusion that can be made from an experiment of this sort is that the copper sulphate solution obviously has the property that it could conduct electricity. Such solution is termed an electrolyte. The wires are called electrodes, the one with positive polarity being the anode, and the one with negative polarity the cathode. The system of electrodes and electrolyte is referred to as the electrolytic cell, whilst the chemical reactions which occur at the electrodes are called the anodic or cathodic reactions or processes.

Electrolytic dissolution
Fig. 2. Electrolytic dissolution of iron.
Electrolytes are different from metallic conductors of electricity in that the current is carried not by electrons but by atoms, or group of atoms, which have either lost or gained electrons, thus acquiring either positive or negative charges. Such atoms are called ions. Ions which carry positive charges move through the electrolyte in the direction of the positive current, that is, toward the cathode, and are called cations. Similarly, the negatively charged ions travel toward the anode and are called anions. The movement of the ions is accompanied by the flow of electrons, in the opposite sense to the positive current in the electrolyte, outside the cell, as shown also in Figure 2 and both reactions are a consequence of the applied potential difference, that is,voltage, from the electric source.

A cation reaching the cathode is neutralized, or discharged, by the negative electrons on the cathode. Since the cation is usually the positively charged atom of a metal, the result of this reaction is the deposition of metal atoms.

To maintain the cathodic reaction, electrons are required to pass around the external circuit. These are obtained from the atoms of the metal anode, and these atoms thus become the positively charged cations which pass into solution. In this case, the reaction is the reverse of the cathodic reaction.

The electrolyte in its bulk must be electrically neutral; that is, there must be equal numbers of opposite charges within it, and thus there must be equal amounts of reaction at both electrodes. Therefore, in the electrolysis of copper sulphate solution with copper electrodes, the overall cell reaction is simply the transfer of copper metal from the anode to the cathode. When the wires are weighted at the end of the experiment, the anodic wire will be found to have lost weight, whilst the cathodic wire will have increased in weight by an amount equal to that lost by the other wire. Some examples of the reactions occurring in these processes are shown in the Appendix.


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2010/11/30

脈衝電化學加工之微電極製作參數分析

在發展微機電系統過程中,製作微結構產品的加工方法是重要且必須的,其中微電化學加工具有可加工任何金屬材料,工件表面無殘留應力,工具電極不損耗等優勢。在微電化學加工中,需要更微細工具電極,方可製造微結構元件,故本文將以製作圓柱狀的微電極為目標。
  本文利用單一因子法分析加工參數(如:操作電壓、電解液濃度、脈衝頻率、加工能率、電解液溫度、電極旋轉速度),再以單一因子法分析的結果;作為第二部份線性變化(如:操作電壓、加工能率)的實驗依據。
  最後本文利用510 μm的鎢棒,以線性遞減操作電壓和加工能率的方式,成功的製作出刃長為2㎜、3㎜、4㎜,電極直徑為100 μm的圓柱狀微電極。

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2010/11/30

脈衝電壓對電化學加工精度之影響

近年來微電化學加工的應用在電化學加工過程中扮演著非常重要的角色,若在微電化學加工系統中施以極短的脈衝電壓,藉著金屬與電解液界面上的電雙層電容器的充電行為,能夠將電化學反應侷限於電極間隙較小的區域,亦即電化學鑽孔加工中的鑽孔區。除了能提高加工精度...
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2010/11/30

電化學加工切削應用領域 / ECM is solving Micromachining problems in a nu


 
ECM is solving Micromachining problems in a number of applications...

 

 

......and new uses are being discovered everyday!

If you would like more information on how to take advantage of 
this technology, or would like to contact us, click the button below.

www.li-fung.biz

精微電化學加工技術在未來各種細微加工應用中佔有極大的優勢。該技術之優點係在於其加工能力與材料硬度無關,且能加工出微細及形狀複雜之表面結構,經由該製程加工後之產品表面具有粗糙度佳、無殘留應力及無裂縫產生等優良特性,常應用於航太、光電半導體、醫療器材、綠色能源、模具等產業上. 精微電化學領域內之各種加工技術,可應用於燃料電池雙極板、生物晶片、微流體動壓軸承、微噴嘴、次世次流體分配閥元件、模具等產品加工上,機會難得,精彩可期。


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2010/11/29

WCU的合金用于EDM(電火花加工)和ECM(電化學加工)電極。

電火花加工(Electrical Discharge Machining)是利用浸在工作液中的兩極間脈沖放電時產生的電蝕作用蝕除導電材料的特種加工方法,又稱放電加工或電蝕加工,英文簡稱EDM。

電火花加工分類

按照工具電極的形式及其與工件之間相對運動的特征,可將電火花加工方式分為五類:利用成型工具電極,相對工件作簡單進給運動的電火花成形加工;利用軸向移動的金屬絲作工具電極,工件按所需形狀和尺寸作軌跡運動,以切割導電材料的電火花線切割加工;利用金屬絲或成形導電磨輪作工具電極,進行小孔磨削或成形磨削的電火花磨削;用于加工螺紋環規、螺紋塞規、齒輪等的電火花共軛回轉加工;小孔加工、刻印、表面合金化、表面強化等其他種類的加工。


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2010/11/29

小直徑薄壁不銹鋼管內壁的脈衝電化學拋光

介紹了對小直徑薄壁不銹鋼細長管內表面進行脈衝電化學拋光的基本方法,初步分析了脈衝參數、工件移動速度等對拋光質量的影響,與直流電作用下的電化學拋光相比,獲得了較好的加工效果。
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