顎式破碎機(jī)機(jī)械結(jié)構(gòu)設(shè)計(jì)【說明書+CAD】

購買設(shè)計(jì)請(qǐng)充值后下載，資源目錄下的文件所見即所得，都可以點(diǎn)開預(yù)覽，資料完整，充值下載可得到資源目錄里的所有文件?！咀ⅰ浚篸wg后綴為CAD圖紙，doc,docx為WORD文檔，原稿無水印，可編輯。具體請(qǐng)見文件預(yù)覽，有不明白之處，可咨詢QQ:12401814 編號(hào)： 畢業(yè)設(shè)計(jì)(論文)外文翻譯（譯文）題 目：基于工具的納米精加工和顯微機(jī)械加工學(xué) 院： 機(jī)電工程學(xué)院 專 業(yè)： 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 學(xué)生姓名： 唐朋 學(xué) 號(hào)： 1000110128 指導(dǎo)教師單位： 桂林電子科技大學(xué) 姓 名： 彭曉楠 職 稱： 副教授 題目類型：理論研究 實(shí)驗(yàn)研究 工程設(shè)計(jì) 工程技術(shù)研究 軟件開發(fā)2014年 5 月 26 日基于工具的納米精加工和顯微機(jī)械加工M. Rahman, H.S. Lim, K.S. Neo, A. Senthil Kumar, Y.S. Wong, X.P. Li機(jī)械工程系，新加坡國立大學(xué)，肯特崗坊10，新加坡119260，新加坡摘 要越來越多的工業(yè)產(chǎn)品不僅需要增加功能的數(shù)量,而且要減小尺寸規(guī)格。精密加工是這樣的小型零部件的生產(chǎn)最基本的技術(shù)。自從以小型技術(shù)的工業(yè)產(chǎn)品為發(fā)展趨勢以來，在當(dāng)今的制造業(yè)，精密加工扮演越來越來重要的角色。以微投影為基礎(chǔ)的顯微加工并不像基于工具的顯微加工技術(shù)有那么多的缺點(diǎn)，比如，車削、研磨、EDM。ECM在生產(chǎn)中有很多優(yōu)勢，比如，生產(chǎn)力、效率、靈活性和成本效率。然而,困難是作為加工單位減少,尚未利用基于工具加工的精密加工技術(shù)解決。然而，當(dāng)傳統(tǒng)的機(jī)械加工部件減少時(shí)，難題是只有當(dāng)基于工具的機(jī)械加工的顯微機(jī)械加工技術(shù)出現(xiàn)時(shí)，問題才可以解決。在這篇文章中，講述了基于工具微加工的一些重要領(lǐng)域的最新成果。摘要介紹了基于工具微加工的一些重要領(lǐng)域最近的成就。介紹了電解敷料(ELID)過程，為了在硬、脆性材料上完成納米表面，單點(diǎn)金剛石工具磨削和超精密加工是兩種應(yīng)用最廣泛的生產(chǎn)技術(shù)。最近這些技術(shù)也在應(yīng)用硅晶片的新一代納米表面硅晶圓，希望能夠替代當(dāng)前的電流技術(shù),化學(xué)機(jī)械拋光(CMP)過程。微電流放電加工(micro-EDM)和微車削技術(shù)被廣泛用于生產(chǎn)小型部件和功能。通常進(jìn)行混合加工時(shí)有高精度的制造的微成分。通常用微型機(jī)床生產(chǎn)此類組件。這種機(jī)器最近的發(fā)展成就也在本文中討論。 2006 Elsevier B.V保留所有權(quán)利。關(guān)鍵字：基于工具的機(jī)械加工、ELID 研磨、微型火花機(jī)、精密車削、混合機(jī)械加工1.介紹由于最近超精密機(jī)械系統(tǒng)的進(jìn)步，微加工越來越受歡迎?，F(xiàn)在有很多致力于制造功能性微觀結(jié)構(gòu)和組件的研究。顯微機(jī)械加工將微影應(yīng)用在硅基質(zhì)上是微結(jié)構(gòu)制做過程的關(guān)鍵。然而,由于它本身類似三維的結(jié)構(gòu)，所以在這個(gè)過程中有一些限制。深X射線利用同步加速器發(fā)射光線（LIGA 加工）。凝聚光線加工制造過程以非常準(zhǔn)確的方式產(chǎn)生高比率的三維次微米結(jié)構(gòu)。但是，這些過程的實(shí)現(xiàn)需要特殊的設(shè)備。最大可實(shí)現(xiàn)的厚度是非常小的【1,2】。傳統(tǒng)材料去除過程,如車削、銑削和磨削,也通過引入單點(diǎn)金剛石銑刀或非常細(xì)粒度大小的磨輪研究了制造微觀結(jié)構(gòu)。這些材料去除過程幾乎可以加工制造所有材料，如金屬、塑料和半導(dǎo)體。加工形狀也沒有限制,因此,需要移動(dòng)部件和導(dǎo)向結(jié)構(gòu)的平面,曲率和長軸都可以加工【3,4】。刨后的零件和非球面的納米級(jí)表面可以通過柔性模式加工或金剛石銑刀單點(diǎn)回轉(zhuǎn)或使用新的磨削方法與固定磨料顆粒完成【5,6】。為了獲得完美的納米表面和準(zhǔn)確作用到脆性材料,普通砂輪與細(xì)磨料尺寸是必要的。當(dāng)用細(xì)小的研磨劑研磨時(shí)，會(huì)遇到砂輪上載荷和裝配等問題。減少上述問題，周期性修正是至關(guān)重要的,這使得磨削過程非常繁瑣。為了為成分的大批量生產(chǎn)，微凸腔體是必須的，這些可以由注塑工藝完成。以控制微米的范圍內(nèi)為目的的的微注射法中，以三維形式加工那些難以加工的工件。對(duì)于復(fù)雜三維模型的裝配，需要用到硬度很大的沖模材料，精密電子束加工是替代機(jī)械加工形式的一種，已經(jīng)被成功運(yùn)用。微型火花機(jī)幾乎可以加工所有的導(dǎo)電材料，無論材料的硬度有多大。用非常細(xì)小的電極來實(shí)現(xiàn)EMD輪廓的控制，可以很成功的制造微型模型。盡管這些方法不能達(dá)到產(chǎn)品裝配的技術(shù)尺寸量級(jí)，比如，在許多情況下，量級(jí)是不需要的。除此之外，產(chǎn)品方案的設(shè)計(jì)和蝕刻技術(shù)也相對(duì)比微加工用機(jī)床價(jià)格更貴。在這篇文章中介紹了基于工具微加工的一些重要領(lǐng)域的成就。2. 新一代的納米表面2.1 新一代的納米表面在加工研磨工序中使用電解質(zhì)2.1.1 ELID磨削原理通過塑性變形而不是斷裂，切削硬性材料和脆性材料可以獲得鏡面拋光表面。當(dāng)使用超細(xì)研磨磨輪ELID磨削是，意識(shí)到了柔性模式的機(jī)加工。當(dāng)用粒度#4000及以上的含有金剛石的金屬砂輪的時(shí)，光滑表面和更少的切削痕跡在玻璃上表現(xiàn)的很明顯。日本村田公司et al .(1985)介紹了電解加工（ELID）過程，用粒度小于#400含有金剛石的金屬砂輪磨削陶瓷，他們發(fā)現(xiàn)了高效磨削硬性材料和脆性材料的方法。Ohmori(1990)進(jìn)一步提高了ELID磨削工藝，他用分級(jí)更細(xì)的沙粒粒度大于#1000，并且還有金屬的磨削砂輪，以電解磨削實(shí)現(xiàn)了更好的表面光潔度。ELID磨削過程的發(fā)展是一個(gè)簡單的技術(shù),可以使用在任何傳統(tǒng)的研磨機(jī)?！?,6】基本的ELID系統(tǒng)包括一個(gè)含有金剛石的金屬砂輪、電極、電源和電解質(zhì)。新加坡國立大學(xué)開發(fā)的ELID系統(tǒng)原理圖如圖1所示。通過應(yīng)用一個(gè)刷子和輪軸平滑的聯(lián)接，將含有金屬的磨削砂輪做成陽極，電極做成陰極。在陽極和陰極之間大約有0.1-0.3mm 的距離，通過磨削液和電流完成電解。圖2顯示了含有金剛石的金屬ELID磨削的機(jī)理。修正后，顆粒和粘接材料的砂輪表面是光滑的。為了預(yù)先布置好在輪子表面突出的顆粒，對(duì)輪子的校準(zhǔn)是必須的。當(dāng)預(yù)加工開始時(shí)，粘結(jié)的材料從磨削砂輪中飛出，在輪子表面絕緣層由被氧化的粘結(jié)材料組成。絕緣層阻斷了輪子表面的導(dǎo)電性，防止過多的粘結(jié)材料從輪子中飛出。開始研磨,金剛石顆粒和絕緣層磨損地很嚴(yán)重。結(jié)果輪子表面的導(dǎo)電率提高，電解質(zhì)從新開始工作，同時(shí)粘結(jié)材料也從磨削砂輪中飛出。磨削砂輪的金剛石突出顆粒因此保持不變。從磨削過程到實(shí)現(xiàn)穩(wěn)定的磨削這個(gè)循環(huán)往復(fù)運(yùn)行。2.1.2 ELID磨削在光學(xué)玻璃納米精加工中的特點(diǎn)（BK7）ELID磨削系統(tǒng)已經(jīng)應(yīng)用于BK7玻璃的磨削,常見的光學(xué)組件的制造材料。通過應(yīng)用ELID磨削技術(shù),在表面粗糙度方面有一個(gè)巨大的進(jìn)步，表面的顯微圖如圖3所示。因?yàn)橹钡较乱粋€(gè)循環(huán)準(zhǔn)備開始時(shí)，磨削砂輪單位面積上的急劇產(chǎn)生的活躍鋒利粗顆粒在磨削期間才會(huì)減少，所以傳統(tǒng)的磨削過程產(chǎn)生較差的結(jié)果。在ELID磨削技巧的實(shí)例中，由于定期的修正，砂輪單位面積上活躍鋒利的顆粒保持不變，這會(huì)提高表面完整性和表面粗糙度。ELID磨削技術(shù)具有減小輪子工作面粘合力的優(yōu)點(diǎn)，因此提高了易磨性。圖1 ELID磨削的設(shè)置圖2 ELID磨削加工過程圖3 比較常規(guī)磨削和ELID磨削工件表面的區(qū)別圖4顯示了在其他層表面磨削砂輪粒度的影響。在機(jī)械加工或預(yù)加工的環(huán)境下，砂輪顆粒大小對(duì)于磨砂玻璃表面的研磨方式的影響很小或者幾乎沒有影響。實(shí)驗(yàn)表明加工環(huán)境影響機(jī)械加工表面的粗造度（圖5）。顆粒被氧化物包裹緊密的結(jié)合在一起，類似精研磨過程。氧化物支撐金剛石顆粒就像拋光襯墊，粘合材料就像支撐襯墊。當(dāng)加工流被應(yīng)用時(shí)，氧化層的厚度會(huì)增加，研磨劑是疏散的，磨削過程幾乎像拋光過程。從實(shí)驗(yàn)結(jié)果來看，適當(dāng)增加氣流的比例表面粗糙度變好的趨勢是顯而易見的。然而，由于在磨損的表面形成了黑色帶狀，所以機(jī)械加工條件（進(jìn)給速度）下有限制。圖6顯示了進(jìn)給速率的影響和當(dāng)前負(fù)載比黑帶的形成,這將影響到表面光潔度。在圖中,標(biāo)志表明黑色地帶的形成。達(dá)到理想的表面光潔度和避免黑帶的形成,重要的是要選擇適當(dāng)?shù)倪M(jìn)給速率和氣流比例。圖4 粒度對(duì)表面的影響圖5 加工過程中條件（當(dāng)前負(fù)載比）對(duì)表面的影響 圖6 ELID磨削的限制條件當(dāng)?shù)倪M(jìn)給速率和深度保持不變，實(shí)驗(yàn)也分析調(diào)查當(dāng)前負(fù)載比和表面粗糙度輪磨損的影響。從圖7中可以很明顯看出,表面粗糙度有所改善,但車輪磨損相應(yīng)地正比比例增加。ELID磨削系統(tǒng)開發(fā)和實(shí)驗(yàn)開展提供了一個(gè)實(shí)際應(yīng)用的解決方案的過程。通過選擇適當(dāng)加工和電解條件,在BK7上，表面光潔度0.01m(Ra)很容易實(shí)現(xiàn)。圖8是微距鏡頭在5mm玻璃棒加工的一個(gè)例子。2.1.3 使用ELID磨削完成硅片納米表面的精加工將拋光技術(shù)用于半導(dǎo)體材料,CMP(化學(xué)機(jī)械拋光)有許多優(yōu)點(diǎn)和一些嚴(yán)重的缺點(diǎn)。 GaAs 和GaP這樣的柔性和脆性材料用CMP技術(shù)可以得到很高效的磨光。然而,這一過程相應(yīng)出現(xiàn)一些缺點(diǎn)，比如，很難拋光硬性和脆性材料如硅(1)低效率除由于低利率,(2)非均勻晶片表面由于晶片的背壓的變化而變化,以及相對(duì)整個(gè)晶圓表面切削速度的變化，(3)參與這個(gè)過程成本相對(duì)較高。另一方面,ELID磨削過程相對(duì)CMP過程有一些重要的優(yōu)勢，是ELID磨削過程取代CMP的拋光方法的潛在優(yōu)勢。超越CMP的一下顯著優(yōu)勢是：(1)由于去除率高、效率高，(2）整個(gè)晶片的表面均勻，(3)參與這個(gè)過程的成本較低。 圖7 加工氣流條件的影響 圖8 通過ELID磨削球形顯微鏡頭(直徑5mm)作者已經(jīng)進(jìn)行的實(shí)驗(yàn)用該ELID磨削過程的整體性能來比較涉及CMP工藝的過程。該ELID磨削操作上進(jìn)行了計(jì)算機(jī)數(shù)字控制（CNC）加工中心（圖9）。在最佳工藝條件，通過觀察確定 被選定與ELID磨削各種參數(shù)，然后在適當(dāng)?shù)臈l件的影響獲得更好的結(jié)果。在ELID磨削參數(shù)的晶圓加工如下：進(jìn)給速度100毫米/分鐘，砂輪粒度8000（粒度1.76m），主軸轉(zhuǎn)速500rpm的轉(zhuǎn)速，切削深度為1納米，ELID電源電壓90 V，最大電流10A.在硅晶片的研磨，材料的去除速率是非常高的，通常6.596 mm3/min可以實(shí)現(xiàn)的。輪的磨損率是可以忽略的。經(jīng)過磨削兩個(gè)晶片到195m厚度，砂輪的厚度沒有變化。表面是完美的韌性和可以實(shí)現(xiàn)鏡子似的拋光，如圖10所示。圖9 ELID磨削對(duì)硅片的實(shí)驗(yàn)裝置2.2 采用超精密加工單點(diǎn)金剛石刀具生成了納米表面（單刀雙擲）2.2.1 超精密加工超精密加工除去物料從幾微米到亞微米級(jí)，在加工難以加工的材料方面實(shí)現(xiàn)延性方式，例如無電解鍍鎳，硅，石英，玻璃和陶瓷，無表面缺陷的技術(shù)。這樣的加工過程中很容易達(dá)到小于10nm鏡面表面的加工，小于1m的形式錯(cuò)誤。如果在特定的范圍適當(dāng)?shù)厥┘拥浇饎偸D(zhuǎn)盤材料，該過程是遠(yuǎn)遠(yuǎn)優(yōu)于研磨和拋光，其中形狀控制是比較困難的，加工時(shí)間變長。實(shí)現(xiàn)超精密加工的一個(gè)重要因素是機(jī)床能夠在納米的分辨率內(nèi)以高精度運(yùn)動(dòng)。這樣的機(jī)床必要的功能包括：剛度、使用振動(dòng)穩(wěn)定性、真空軸承主軸，低運(yùn)行速度、閉環(huán)控制器、納米級(jí)分辨率的反饋。在新加坡國立大學(xué)的先進(jìn)制造實(shí)驗(yàn)室有一個(gè)這樣的機(jī)器是東芝ULG100C （ H3 ）的超精密機(jī)床。另一個(gè)重要因素是采用由單晶金剛石高品質(zhì)的工具無論是自然的還是制造的。單晶直徑的優(yōu)點(diǎn)包括高的硬度和耐磨性，對(duì)加工過程中的除熱良好的導(dǎo)熱性，并且可以實(shí)現(xiàn)20nm的納米級(jí)切削鋒利的切削刃半徑。要考慮的其它重要因素包括刀具幾何形狀，刀具磨損，冷卻劑供給，切削條件和被加工材料的特性。 SPDT在一個(gè)轉(zhuǎn)動(dòng)安裝的工作，是通常被稱為金剛石車削加工設(shè)置，如在圖11所示 。2.2.2 化學(xué)鍍鎳金剛石車削鍍成型模具超精密加工技術(shù)一個(gè)主要應(yīng)用是化學(xué)鍍鎳的金剛石車削電鍍成型模具的塑料光學(xué)部件，如液晶或投影電視。然而，構(gòu)成一個(gè)很大的挑戰(zhàn)就是刀具的直徑壽命短，蒙德切割機(jī)和拋光工藝金剛石車削后是必需的。這是不希望的研磨面的形狀誤差是次于金剛石翻面。因此，只保留車削加工這種模具和該項(xiàng)目的目標(biāo)是提高金剛石切削工具是很重要的，生活中通過鉆石刀具的設(shè)計(jì)和加工條件的材料特性優(yōu)化化學(xué)鍍鎳。新加坡國立大學(xué)的先進(jìn)制造實(shí)驗(yàn)室，在進(jìn)行一個(gè)項(xiàng)目工作是在日立公司，與日本的PERL合作，深入研究這個(gè)問題。該過程已建立化學(xué)鍍鎳壓模的金剛石車削，已經(jīng)達(dá)到表面粗糙度小于6nm（Ra）。已經(jīng)建立影響金剛石刀具磨損的主要因素：（a）的化學(xué)鍍鎳組合物，（b）該金剛石刀具的晶體取向，金剛石采用的（c）該類型（人造或天然）（d）該金剛石刀具的前角?？紤]到這些，已經(jīng)達(dá)到200km長的切割距離，仍保持0.12 mm Ry鏡面光潔度。下面的小節(jié)說明進(jìn)行該項(xiàng)目的主要成果。2.2.2.1。針對(duì)不同的化學(xué)鍍鎳（EN）組成銑刀的性能的調(diào)查。在無電解鍍鎳的金剛石車削，鎳和磷的化學(xué)鍍鎳的組合物關(guān)于其機(jī)械加工性顯著影響有兩個(gè)原因。首先，如鎳和鐵的工作作為催化劑元素，它促進(jìn)了金剛石- 石墨轉(zhuǎn)變（圖10），因此更大量的鎳相比磷會(huì)導(dǎo)致金剛石刀具更大的磨損。 其次，在無電解鎳磷含量的顯著影響，其結(jié)構(gòu)和硬度（圖11）?；瘜W(xué)鍍鎳具有較低的磷含量趨向于更脆，硬，因此難以加工。實(shí)驗(yàn)對(duì)削減了5.7的工件和11.5（W / W）的磷以觀察切割性能，從而建立了優(yōu)選化學(xué)鍍鎳組合物，如Pramanik等所詳述（圖12）。 圖10 鏡面拋光硅表面 圖11 端面車削設(shè)置切削刀具性能包括表面光潔度、磨損與切削距離，不同磷含量的定量比較如圖12-15所示。顯而易見磨損率是很小的，幾乎是恒定的11.5（ W / W ）的磷含量，從而保持良好的表面光潔度。另一方面，用5.7 （ W / W）的磷含量加工電鍍鎳，在加工有切割大約100km處被停止時(shí)，刀具的磨損是如此之高。比較被用于機(jī)械加工的電解用不同的磷含量，該切割器的顯微照片（圖12和13），明顯磨損嚴(yán)重。磷在化學(xué)鍍鎳中不僅影響其硬度和材料的結(jié)構(gòu)，但是也以作為潤滑劑，以輔助加工過程。雖然化學(xué)鍍鎳的磷含量較低，在加工過程中發(fā)現(xiàn)無脆裂比較難。所以磷含量起著改變化學(xué)鍍鎳和刀具磨損的特性的角色，從實(shí)驗(yàn)結(jié)果可以假定磷減輕鎳的催化作用，促進(jìn)金剛石石墨轉(zhuǎn)化。很顯然，磷保護(hù)刀具免受損壞，并有利于無電鍍鎳的可加工性。圖12 EN 5.7P（W / W）距離93.6km面切割，側(cè)翼（a）和耙（二）的磨損。圖13 EN 11.5P（W / W）距離202.3km的端面切削，側(cè)翼（a）和耙（二）的磨損2.2.2.2 很長的切割距離（ 200km）晶體取向?qū)Φ毒咝阅苡绊憽１娝苤?，單晶金剛石呈現(xiàn)各向異性，從而其特性取決于方向和晶體取向。因此，在單晶金剛石工具之前，晶體取向的性能測試具有非常重要的商業(yè)用途。兩種類型的結(jié)晶取向，即（1 1 0）和（1 0 0），在前面已被研究。2.2.3 切削條件和硅片的納米級(jí)球墨鑄鐵切削刀具刃口半徑研磨頻繁導(dǎo)致亞表面損傷，當(dāng)前方法必須通過拋光來去除加工硅片。所以建議使用金剛石單點(diǎn)切削刀具的超精密機(jī)床上建立球模式加工制度，以提高收益率。由于脆性斷裂可被最小化和零件在服務(wù)的可靠性，這種方式損壞可以得到改善。為了實(shí)現(xiàn)延性域加硅的加工，研究人員以前的工作如圖13、圖14所示，對(duì)半導(dǎo)體材料的韌脆轉(zhuǎn)變加工的未變形切屑厚度的增加。圖15表明切割硅的臨界深度為58nm。它也顯示了刀具切削刃的幾何形狀對(duì)實(shí)現(xiàn)延性模式切削有顯著作用圖16、圖17。圖14 磷含量對(duì)切割表面粗糙度（Ra）距離的影響 圖15 影響切割的磨損距離，不同磷含量 圖16 側(cè)翼（a）和耙（b）切割距離為202km，前刀面（110）金剛石刀具（500）后端面磨損。雖然在此前已經(jīng)有上球模式切屑形成的硅材料切割所做的研究工作，一直在切削條件沙子刀具切削刃半徑硅片的納米級(jí)球墨鑄鐵切削模式?jīng)]有詳細(xì)的報(bào)告。在本研究中，切削條件和對(duì)硅晶片的納米級(jí)延性模式切削刀具的切削刃半徑已經(jīng)通過實(shí)驗(yàn)測試研究。硅晶片的端面車削實(shí)驗(yàn)，進(jìn)行了1nm定位的超精密車床（東芝ULG-100C）使用金剛石工具有0到7、間隙為0.5mm半徑的分辨率。直徑100mm、厚0.5mm，并具有重疊的完成硅（111）晶片用作樣本。切屑形成在硅晶片的延性切削的示意圖如圖20所示。這里R是切削刃半徑，刀具的前角，興趣區(qū)切割深度。使用六種不同的切削刃半徑，在23807 nm處金剛石刀具刃口半徑單晶金剛石刀具，Li等進(jìn)行切削通過壓痕法Li等進(jìn)行測定（圖18）。切削半徑的使用被設(shè)計(jì)（圖17）一種特殊的包處理來實(shí)現(xiàn)。超精密端面車削實(shí)驗(yàn)的切削條件列于表1。干式切削，目的用于進(jìn)行收集切割碎片。用電子顯微鏡（SEM）（JEOL JSM-5500）掃描加工工件的表面紋理和芯片形成進(jìn)行了研究。使用原子力顯微鏡（AFM）的加工的工件表面形貌進(jìn)行了檢查。使用表單跟蹤器（三豐CS-5000）硅片的加工表面粗糙度進(jìn)行了檢查。使用金剛石工具用在切割為150m/min的速度不同的切削刃的半徑在硅晶片的切割加工表面的原子力顯微鏡照片示于圖21。為23、202、490、623和717 nm的金剛石刀具刃口半徑，一次測試中，條件是未變形切屑厚度小于刀具刃口半徑和其他測試條件下進(jìn)行下進(jìn)行的未變形切屑厚度比刀具刃口半徑大。對(duì)于807nm金剛石刀具刃口半徑，無論是測試的條件還是未變形切屑都是在厚度小于刀具刃口半徑下進(jìn)行。這是通過掃描電子顯微鏡觀察該顯示連續(xù)的切屑類似的形成于韌性材料，其中芯片的形成是由位錯(cuò)為主的切削證實(shí)。另一方面，當(dāng)未變形切屑厚度比刀具的切削刃半徑越大，這表明在切割被下脆模式進(jìn)行，加工的工件表面非常粗糙，裂縫很大。圖17 側(cè)翼（a）和耙（二）端面切削距離202.3km，前刀面（100）金剛石刀具（500）后磨損。表格1切割的超精密切削試驗(yàn)條件圖18 不同切割晶體取向?qū)η懈畹哪p距離的影 圖19針對(duì)不同的切割晶體取向，對(duì) 切削距離表面粗糙度（Ra）的影響圖20 切屑形成了脆性材料的延性切削示意圖圖22 多功能微型機(jī)床 圖21 在不同的未變形切屑加工硅片表面原子力顯微鏡照3 采用混合處理工具為基礎(chǔ)的微機(jī)械加工3.1。微型機(jī)床多工序加工的發(fā)展 多用途微型機(jī)床已發(fā)展為高精度微細(xì)加工（19），圖22示出了桌面微型機(jī)床的結(jié)構(gòu)。該機(jī)床具有560 mm（W）*高度600 mm（D）660毫米（H），最大行程范圍是210mm（X）110mm（Y）110mm（Z）。每個(gè)軸都有光學(xué)線性度為0.1m分辨率，以及全閉環(huán)反饋控制，保證亞微米級(jí)的精度。機(jī)床使多變的高速、中速和低速主軸為微銑削、微車削和微粉磨機(jī)上。低速主軸電從機(jī)器的主體分離，使電機(jī)系列-ING，如電火花和ECM中，可以在機(jī)器上進(jìn)行。運(yùn)動(dòng)控制器可以執(zhí)行從獨(dú)立于主機(jī)計(jì)算機(jī)下載的程序。因此，可實(shí)時(shí)實(shí)現(xiàn)一個(gè)良好的電火花加工間隙控制。因?yàn)殡娀鸹庸み^程中快速移動(dòng)所需的的間隙控制，所以各軸的響應(yīng)是很重要。Z-軸顯示了0.1024mm處高達(dá)10赫茲和共振頻率100赫茲，這是控制放電加工過程的火花間隙足夠的距離。3.2使用微細(xì)電火花加工高深寬比微細(xì)加工微放電加工（EDM）是已發(fā)現(xiàn)的最有效的技術(shù)制造的微部件之一的非傳統(tǒng)加工技術(shù)。非接觸型方法需要電極和工件之間的力小，并且能夠加工韌性的、脆性或超級(jí)硬化的材料。用適當(dāng)?shù)膮?shù)，它有可能用微細(xì)電火花加工，以達(dá)高精度及高品質(zhì)加工。電火花加工的非接觸性質(zhì)使得可以使用非常長的和薄的電極的加工。盡管微銑刀向下的距離為50m，這在市場上很有價(jià)值，刀具的長度通常是其直徑的3-5倍，它也是不適合的機(jī)器很吃力模具材料，其僅可以使用電火花加工。雖然微細(xì)電火花加工中在微細(xì)加工領(lǐng)域中起重要作用，但它也有缺點(diǎn)，如高電極消耗率和低材料去除速率。為了進(jìn)一步使加工得到補(bǔ)償，電極的損耗必須通過改變電極或通過從開始不再準(zhǔn)備電極或制造原位電極。這是加工過程中不推薦改變所述微電極，由于在安裝或重新擰緊的微電極的變化，它可能會(huì)降低精度。圖23示出使用微放電加工以制造高縱橫比的微結(jié)構(gòu)的概念性流程。在微電火花加工過程中，工具電極被制造在機(jī)器上，以避免夾緊誤差。從一個(gè)電極比所需的直徑變粗，一個(gè)圓柱形電極通過電火花加工過程中使用的犧牲電極制成。不同的設(shè)置犧牲的電極可在此過程中（圖23的（a）項(xiàng)）被使用。當(dāng)存在所述犧牲電極尺寸變化時(shí)，制造的工具電極的直徑通常是不可預(yù)測的。一個(gè)對(duì)工具電極直徑的測量機(jī)，需要在這種情況下（圖23（ b）項(xiàng)） 。這種光學(xué)測量裝置已用于薄電極，它由一個(gè)激光二極管、光學(xué)濾波器和光電檢測器的測量而特別開發(fā)的。測量直徑后，對(duì)工具電極制造一個(gè)補(bǔ)償加工時(shí)間表生成和加工進(jìn)行。重復(fù)實(shí)現(xiàn)這些過程直到獲得所需的工具電極直徑。精加工工具電極在制造完成后，微放電加工進(jìn)行制造的高縱橫比的微結(jié)構(gòu)（圖23（c）項(xiàng)） 。圖 23 使用微細(xì)電火花加工過程中制作高深寬比微結(jié)構(gòu)在研究工具電極的制造過程中，三個(gè)不同的犧牲電極進(jìn)行測試，以比較它們的功能和性能。圖24示出了三種不同類型的犧牲電極。圖24（a）示出了一個(gè)固定的塊，這是最簡單的方法來加工工具電極。圖24（b）示出了具有0.5mm的厚度和直徑60mm的旋轉(zhuǎn)電極。盤電極的旋轉(zhuǎn)速度是工具制造過程中約90n/min。圖24（c）示出了引導(dǎo)運(yùn)行線作為0.07mm直徑的犧牲電極。該線的運(yùn)行速度大約為3-5mm/s。這種方法被稱為線性電極電火花磨削（WEDG ），并且它是微EDM的典型方法。在工具制造過程中，主軸旋轉(zhuǎn)約300rpm，它根據(jù)刀具電極的接觸條件上下移動(dòng)。這意味著該主軸是在控制之下，以維持放電的火花間隙。一旦刀具到達(dá)其沖程運(yùn)動(dòng)的一個(gè)端部，該工具向電極移動(dòng)到切口的一個(gè)給定的深度，并重復(fù)該過程。圖25顯示了在使用微細(xì)電火花加工不同類型的犧牲電極制作一些典型的電極形狀。圖25（a）示出了使用固定的銅塊工具電極加工。所制造的工具電極的表面通常是光滑的。然而，該形狀精度沒有希望的那么好，并且該工具通常有一些錐度。工具電極上的錐形形狀是由于在犧牲電極的磨損。因?yàn)樵谥圃爝^程中刀具向上和向下移動(dòng)工具，下部（尖端）部分具有更大的機(jī)會(huì)來面對(duì)犧牲電極，并因此經(jīng)受更多的排放，因此加工。電極塊向工具電極的輕微傾斜，不利于提高錐形形狀。該電極仍具有如圖所示的不均勻直徑。25（b）所示。固定犧牲塊電極易于安裝;然而，其形狀和尺寸不容易控制。圖 24 三種類型的犧牲電極為了機(jī)床制造圖25 機(jī)器制造工具電極的典型形狀。（a）使用一個(gè)固定的犧牲塊錐形工具電極加工。（b）使用一個(gè)固定的犧牲塊不均勻直徑加工。（c）電極用旋轉(zhuǎn)盤加工。使用運(yùn)行線（d）電極加工。圖 26 由微細(xì)電火花加工制成微特征。（a）微槽; （b）三角孔; （c）微電極; （d）微裂紋。圖25（c）示出使用旋轉(zhuǎn)犧牲電極工具電極的制造的一個(gè)例子。在這個(gè)例子中，有加工時(shí)侵蝕在旋轉(zhuǎn)電極放電。然而，侵蝕分布幾乎均勻地分布在電極的整個(gè)周長。考慮到工具電極和犧牲電極之間的直徑差，在使用微細(xì)電火花加工工具電極制造，旋轉(zhuǎn)電極的尺寸變化是幾乎可以忽略不計(jì)。厚度為0.5mm的旋轉(zhuǎn)電極給出了相同效果的表面光潔度的固定電極，因?yàn)樗亲銐驅(qū)?，可以完成一個(gè)平滑的表面。圖25（d）是用運(yùn)行絲機(jī)加工工具電極放電加工的典型的表面狀態(tài)。這個(gè)過程被稱為導(dǎo)線電火花磨削（WEDG），并已被廣泛用于微細(xì)電火花加工。因?yàn)樾陆z被連續(xù)地使用時(shí)，該犧牲電極的尺寸變化在理論上是零。這實(shí)際上確保了微細(xì)電火花加工高精度三維控制。然而，表面處理效率與高旋轉(zhuǎn)電極法不一樣。正是由于這一事實(shí)，即運(yùn)行絲的直徑僅為0.07mm，用于旋轉(zhuǎn)電極電火花加工間隙控制的相同的條件下順利完成機(jī)加工的表面，這是不夠使用。實(shí)現(xiàn)使用這種薄金屬絲較好的表面，在精加工過程的速度必須減小。從三個(gè)不同的方法進(jìn)行比較，研究發(fā)現(xiàn)旋轉(zhuǎn)電極法是制作工具電極的最有效的方法。即使旋轉(zhuǎn)電極的磨損不為零時(shí)，該電極的直徑可以用在機(jī)測量隨后被控制補(bǔ)償進(jìn)行加工。做出一系列的測試后，各個(gè)微形狀使用的是微放電加工制成。圖26（a）示出了在鎢棒上制造一個(gè)微隙寬度為200m左右。掃描電火花加工過程被用于加工。圖26（b）示出了在不銹鋼板加工一個(gè)三角形的孔上。實(shí)現(xiàn)的形狀是500m的鎢電極被加工成三角形。為了達(dá)到形狀，加工50m的鎢電極，先用WEDG工藝，然后微細(xì)電火花下沉加工三角形狀模具。圖26（c）表示使用WEDG 直徑50mm的微電極進(jìn)行加工的過程。圖26（d）表示使用微掃描電火花加工鋁工件模擬微裂紋的加工過程。3.3。利用微車削加工薄電極微放電加工（電火花）是一種非傳統(tǒng)的加工技術(shù)。這是最有效制造微元件技術(shù)之一。非接觸型方法需要電極和工件之間的力小，并且能夠延展性加工，脆性或超級(jí)硬化的材料。根據(jù)相應(yīng)的參數(shù)，它有可能為微細(xì)電火花設(shè)置高精度，高品質(zhì)加工。雖然微細(xì)電火花加工微細(xì)加工領(lǐng)域中起重要作用，它也有缺點(diǎn)，如高電極消耗率和低的材料去除速率。電極的損耗必須通過改變電極或通過從開始準(zhǔn)備電極或制造原位電極用于進(jìn)一步加工得到補(bǔ)償。這是加工過程中不推薦的，改變所述微電極，因?yàn)樗赡軙?huì)由于夾緊降低精度。由于低剛度，較長電極加工處均引入偏轉(zhuǎn)，如圖27（a）。圖 27 高精度微細(xì)電火花加工的概念 （a）與薄電極電火花;（b）轉(zhuǎn)電火花加工混合。圖 28 微型軸加工過程中變形圖27（b）示出了旋轉(zhuǎn)電火花混合加工的概念。這種混合加工工藝，電火花加工是使用一個(gè)轉(zhuǎn)動(dòng)軸。一個(gè)電極所需的長度是利用微車削工藝制造。使用這種混合加工，能夠避免夾緊引起的誤差，電極的偏轉(zhuǎn)可以被最小化，從而加工精度得到改善。優(yōu)先選擇不同直徑的電極，與WEDG方法相比，可轉(zhuǎn)動(dòng)的電極制備顯著減少。這種混合的加工技術(shù)也可通過電火花加工過程中的幫助，用于制造圓柱形微型元件與非旋轉(zhuǎn)部分，如后轉(zhuǎn)動(dòng)的鍵、槽或扁鋼。在使用車削加工薄電極的一個(gè)問題是在工件的加工過程中的撓曲。圖28示出的用偏轉(zhuǎn)測量傳感器測量工件的端部的偏轉(zhuǎn)。從該實(shí)驗(yàn)中，我們觀察到工件未彎曲僅在刀具和工件接觸區(qū)的正常方向（X）;它也偏轉(zhuǎn)在切線方向（Y）。事實(shí)上，工件偏轉(zhuǎn)朝向切削工具的頂面（前刀面）。制造高度精確的細(xì)軸，Y方向上的偏轉(zhuǎn)也必須根據(jù)工件直徑的變化進(jìn)行補(bǔ)償?？紤]到減少偏轉(zhuǎn)，影響工件偏轉(zhuǎn)的另一個(gè)因素是步長。圖29示出的步長大小的步誤差和工件的撓曲的影響。，步長增大，它是觀察到的步長大小的步長誤差的影響比切削深度更占優(yōu)勢時(shí)。對(duì)于薄電極轉(zhuǎn)動(dòng)，降低步長是減少電極的整體誤差的一個(gè)實(shí)施辦法。 圖 29 步長對(duì)步長誤差和撓度的影響微轉(zhuǎn)動(dòng)部件部分樣品如圖30所示。圖30（a）示出了具有33m直徑的微電極。圖30（b）示出了高縱橫比的微軸直徑為0.1mm，長度為15mm。這樣高的縱橫比可以用來實(shí)現(xiàn)最小步長小于0.5mm的微車削。圖30（c）示出微軸具有不同直徑和特征，軸被用作超聲微電機(jī)的主軸。圖 30 微車削件（a）33米直徑的電極（b）的高縱橫比的軸（c）微電機(jī)軸4 結(jié)論在本文中，在介紹了工具為基礎(chǔ)的納米表面生成和微加工領(lǐng)域的一些重要的和廣泛使用的最新成果。目前的實(shí)驗(yàn)結(jié)果顯示在ELID磨削領(lǐng)域一些可實(shí)現(xiàn)的一個(gè)突破是硅片的納米整理。采用單點(diǎn)金剛石刀具加工納米表面的過程表明，通過選擇合適的幾何角度刀具和切削條件下，可保持納米整理達(dá)到很長的壽命。已被證明了的多用途微型機(jī)床能夠進(jìn)行混合加工是對(duì)微型和小型元件的精度微加工一個(gè)很好的解決方案。參考文獻(xiàn)1 H. Okuyama, H. Takada, Micromachining with SR and FEL, Nucl. Instrum.Methods Phys. Res. B 144 (1998) 5865.2 S. Matsui, T. Kaito, J.-I. Fujita, M. Ishida, Y. Ochiai, Three-dimensional nanostructure fabrication by focused-ion-beam chemical vapor deposition, J. Jpn. Soc. Prec. Eng. 67 (9) (2001) 14121415 (in Japanese).3 Z. Lu, T. Yoneyama, Micro cutting in the micro lathe turning system, Int. J.Mach. Tools Manuf. 39 (1999) 11711183.4 M. Rahman, A.S. Kumar, J.R.S. Prakash, Micro milling of pure copper, J.Mater. Process. Technol. 116 (2001) 3943.5 R. Murata, K. Okano, C. Tsutsumi, Grinding of structural ceramics,Milton C Shaw Grinding Symposium PED, vol. 16, 1985, pp. 261272.6 H. Omori, T. Nakagawa, Mirror surface grinding of silicon wafers with electrolytic in-process dressing, Ann. CIRP 39 (1) (1990) 329333.7 T. Masuzawa, C.L. Kuo, M. Fujino, Drilling of deep micro holes by EDM,Ann. CIRP 38 (1989) 195198.8 T. Masuzawa, C.L. Kuo, M. Fujino, A combined electrical machining process for micronozzle fabrication, Ann. CIRP 43 (1994) 189192.9 S.C. Jacobsen, R.H. Price, J.E. Wood, T.H. Rytting, M. Rahaelof, The wobble motor: design, fabrication and testing of an eccentric motion electrostatic microactuator, in: Proceedings of the IEEE International Conference on Robotics Automation, Scottsdale, AZ, USA, 1419 May, 1989, pp.15361545.10 J. Wilks, E. Wilks, Properties and Applications of Diamond, Butterworth Einemann Publications, Oxford, 1991 (Chapter13).11 J.W. Dini, C.K. Syn, J.S. Taylor, G.L. Mara, R.R. Vandervoort, R.R. Donaldson, Inuence of phosphorus content and heat treatment on the machinability of electroless nickel deposits, in: Proceedings of the IVth Electroless Nickel Conference (Chicago), Gardner Publications, Cincinnati, 1995, pp.5-15-15.12 A. Pramanik, K.S. Neo, M. Rahman, X.P. Li, M. Sawa, Y. MeIada, Cutting performance of diamond tools during ultra-precision turning of electroless nickel plated die materials, J. Mater. Process. Technol. 140 (13) (2003) 308313.13 W.S. Blackley, R.O. Scattergood, Chip topography for ductile-regime machining of germanium, ASME Trans. J. Eng. Ind. 116 (1994) 263266.14 F.Z. Fang, V.C. Venkatesh, Diamond cutting of silicon with nanometric nish, Ann. CIRP 47 (1998) 4549.15 J. Yan, K. Syoji, T. Kuriyagawa, H. Suzuki, Ductile regime turning at large tool feed, J. Mater. Process. Technol. 121 (2002) 363372.16 D.A. Lucca, P. Chou, R.J. Hocken, Effect of tool edge geometry on the nanometric cutting of Ge, Ann. CIRP 47 (1998)475478.17 K. Liu, X.P. Li, M. Rahman, K.S. Neo, C.C. Chan, X.D. Liu, A study of the effect of tool cutting edge radius on ductile cutting of silicon wafers,Int. J. Adv. Manuf. Tech., in press.18 X.P. Li, M. Rahman, K. Liu, K.S. Neo, C.C. Chan, Nano-precision measurement of diamond tool edge radius for wafer fabrication, J. Mater. Process.Technol. 140 (2003) 358362.19 H.S. Lim, A. Senthil Kumar, M. Rahman, Improvement of form accuracy in hybrid machining of microstructure, J. Electron. Mater. 31 (10) (2002) 10321038. 編號(hào)： 畢業(yè)設(shè)計(jì)(論文)外文翻譯（原文）題 目：Tool-based nanonfishingand micromachining學(xué) 院： 機(jī)電工程學(xué)院 專 業(yè)： 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 學(xué)生姓名： 唐朋 學(xué) 號(hào)： 1000110128 指導(dǎo)教師單位： 桂林電子科技大學(xué) 姓 名： 彭曉楠 職 稱： 副教授 題目類型：理論研究 實(shí)驗(yàn)研究 工程設(shè)計(jì) 工程技術(shù)研究 軟件開發(fā)2014年 5 月 26 日Tool-based nanonishing and micromachiningM. Rahman , H.S. Lim, K.S. Neo, A. Senthil Kumar, Y.S. Wong, X.P. LiMechanical Engineering Department, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, SingaporeAbstractThere is a growing demand for industrial products not only with increased number of functions but also of reduced dimensions. Micromachining is the most basic technology for the production of such miniaturized parts and components. Since miniaturization of industrial products had been the trend of technological development, micromachining is expected to play increasingly important roles in todays manufacturing technology. Micromachining based on lithography has many disadvantages unlike tool-based micromachining technology such as micro-turning, grinding, EDM and ECM have many advantages in productivity, efciency, exibility and cost effectiveness. However, difculties, as the machining unit reduced, are yet to be solved to utilize the tool-based machining technology for micromachining. In this paper, recent achievements in some important areas of tool-based micromachining are introduced. Electrolytic in-process dressing (ELID) grinding and ultra precision machining using single point diamond tool are two most widely applied techniques to produce nano-surface nish on hard and brittle materials. Recently these techniques are also being applied for nano-surface generation on silicon wafers and it is hoped that this process will be able to replace the current technique, chemical mechanical polishing (CMP) process.Micro-electro-discharge machining (micro-EDM) and micro-turning technology are widely used to produce miniaturized parts and features. Usually hybrid machining is carried out to fabricate micro-components with high precision. Usually multi-purpose miniature machine tools are used to produce such components. Recent achievements on the development of such machines are also discussed in this paper. 2006 Elsevier B.V. All rights reserved.Keywords: Tool-based machining; ELID grinding; Micro-EDM; Micro-turning; Hybrid machining1. IntroductionMicromachining is gaining popularity due to the recent advancements in Micro-Electro Mechanical Systems. Many studies have been carried out to fabricate functional microstructures and components. Micromachining technology using photolithography on silicon substrate is one of the key processes to fabricate the microstructures. However, there are some limitations in this process due to its quasi-three-dimensional structure, its low aspect ratio and limitation of the working material. Deep X-ray lithography using synchrotron radiation beam (LIGA process) and focused-ion beam machining process can produce high aspect ratio three-dimensional sub-micron structures with very high form accuracy. But, these processes require special facilities, and the maximum achievable thickness is relatively small1,2. Conventional material removal processes, such as turning, milling and grinding, are also studied to fabricate microstructures by introducing a single point diamond cutter or very ne grit sized grinding wheels. These material removal processes can machine almost every material such as metals, plastics and semiconductors. There is also no limitation in machining shape, so that at surfaces, arbitral curvatures and long shafts can be machined, which are required for the moving parts and guiding structures 3,4. Planer and aspheric surfaces with nano-surface nish can also be produced by ductile mode machining either by single point turning using diamond cutter or with xed abrasive grains using new grinding methods 5,6. To obtain nano-surface nish and accuracy on brittle materials, grinding wheels with ne abrasive size are needed. Problems such as wheel loading and glazing are encountered while grinding with ne abrasives. Periodic dressing is essential to minimize the above problems and this makes the grinding process very tedious. Micro-mould cavities are also needed for mass-production of micro-components, which can be made by injection molding process. Hard-to-machine work-piece materials should be machined very precisely in three-dimensional forms in the micron range for the purpose of microinjection. For the fabrication of complex three-dimensional molds using very tough die materials, micro-electro-discharge machining (EDM) is one of the alternative machining processes that can be used successfully. Micro-EDM can machine almost every conductive material, regardless of its stiffness. Using a very thin electrode with control of the EDM contour, micro-molds can be produced successfully. Although these methods cannot reach the dimensional magnitudes of photo fabrication techniques, such magnitudes are not required in many cases. Besides these, the set up cost for the photo fabrication and etching techniques are also comparatively more expensive than micromachining using machine tools. In this paper, recent achievements in some important areas of tool-based micromachining are introduced.2. Nano-surface generation2.1. Nano-surface generation using electrolytic in-process dressing (ELID) grinding2.1.1. Principle of ELID grindingIt is possible to obtain mirror surface nishes on hard and brittle materials when material removal takes place through plastic deformation rather than fracture. Ductile mode machining can be realized when using super ne abrasive grinding wheels together with ELID grinding. Smoother surface and fewer grinding mark son the glass surface was observed when metal bonded diamond grinding wheel of grit size 4000 and above was used 79.Murata et al. (1985) introduced electrolytic in-process dress-ing (ELID) to grind ceramic with metal bonded diamond wheel of grit size less than #400 and they found the method to be efcient for grinding hard and brittle materials. ELID grinding was further improved by Ohmori (1990) with metal bonded grinding wheels of ner grades with grit size more than #1000 that was electrolytically dressed during grinding to realize ne surface nish. The developed ELID grinding process is a simple technique that can be used on any conventional grinding machine5,6.The basic ELID system consists of a metal bonded diamond grinding wheel, electrode, power supply and electrolyte. A schematic of an ELID system developed in NUS is shown in Fig. 1. The metal bonded grinding wheel is made into the positive pole through the application of a brush smoothly contacting the wheel shaft and the electrode is made into negative pole. In the small clearance of approximately 0.10.3 mm between the positive and negative poles, electrolysis occurs through the supply of the grinding uid and an electrical current. Fig. 2 shows the mechanism of ELID grinding of metal bonded diamond wheel. After truing (a), the grains and bonding material of the wheel surface are attened. It is necessary for the trued wheel to be electrically pre-dressed to protrude the grains on the wheel surface. When pre-dressing starts (b), the bonding material ows out from the grinding wheel and an insulating layer composed of the oxidized bonding material is formed on the wheel surface (c). This insulating layer reduces the electrical conductivity of the wheel surface and prevents excessive ow out of the bonding material from the wheel. As grinding begins (d), diamond grains wear out and the layer also become worn out (e). As a result, the electrical conductivity of the wheel surface increases and the electrolytic dressing restarts with the ow out of bonding material from grinding wheel. The protrusion of diamond grains from the grinding wheel therefore remains constant. This cycle is repeated during the grinding process to achieve stable grinding.2.1.2. Characteristics of ELID grinding on nano-nishing optical glass (BK7)The ELID grinding system developed has been applied to the grinding of BK7 glass, a common material for the manufacture of optical components. By applying the ELID grinding technique, there was a vast improvement in the surface roughness of the ground surface as shown in the micrographs of the ground surfaces in Fig. 3. The conventional grinding process produces poorer nish because the active sharp grits per unit area of the grinding wheel decreases during grinding until the next dressing cycle. In the case of the ELID grinding technique, the active sharp grits per unit area of the wheel remain the same due to constant dressing and this leads to improved surface integrity and surface roughness. The ELID grinding technique also has the advantage of reducing the bonding strength of the wheel- working surface, hence improving grind-ability.Fig. 1. ELID grinding setup.Fig. 2. In-process dressing in ELID grinding.Fig. 3. Comparison of ground surface generated with (a) conventional grinding and (b) ELID grinding (50% current).Fig. 4. Effect of grit size on the surface generation Fig. 5. Effect of in-process dressing condition (current duty ratio) on surface generation.Fig. 4 shows the effect of grinding wheel grit size on the surface generation. The grinding mode of the ground glass surface is inuenced by the grit size of the wheel that has very little or no inuence on the machining and pre-dressing conditions. The experiments show that the in-process dressing condition affects the surface roughness of the machined surface (Fig. 5). The grit held by the oxide layer is loosely held in the bond and the process is same as the lapping process. The oxide layer holding the diamond grit is like the lapping pad and the bonding material acts like a supporting pad. When more dressing current is applied, thickness of the oxide layer increases, the abrasives are loosely bonded and the grinding process becomes almost like polishing process. From the experiments it was observed that the surface roughness is better when the current duty ratio increases. However, there is limitation in terms of machining condition (feed rate) feed rate, due to a black strip formation on the ground surface.Fig. 6 shows the effect of feed rate and current duty ratio on the black strip formation, which will affect the surface nish. In the gure, marks indicate the formation of the black strip. To attain the desired surface nish and avoiding black strip formation, it is important to select the appropriate feed rate and current duty ratio.Experiments are also conducted to investigate the inuence of the current duty ratio on the surface roughness and wheel wear, when the feed rate and depth of cut are kept constant. From Fig. 7, it is clear that the surface roughness ha improved but the wheel wear increases proportionally with the current duty ratio.The ELID grinding system that was developed and the experiments carried out has provided a practical application solution of the process. Through appropriate selection of machining and electrolytic dressing conditions, a surface nish of 0.01m (Ra) is easily achievable on BK 7. Fig. 8 is an example of macro lens machined on a 5 mm glass rod.2.1.3. Nano-surface nishing of silicon wafer using ELID grindingAmong the polishing techniques used for semiconductor materials, CMP (Chemical mechanical Polishing) has many advantages and few serious disadvantages too. Materials which are soft and brittle like GaAs and GaP are efciently polished by the CMP technique. However, some of the disadvantages associated with this process for polishing hard and brittle materials like silicon are (i) low efciency due to low removal rates, (ii) non-uniform wafer surface due to the variation in the back pressure of wafer, and the variation in relative cutting speed across the wafer surface, and (iii) relatively high cost involved in this process. On the other hand, the ELID grinding process has some important advantages over the CMP process, and there is a potential for the ELID grinding process to replace the CMP polishing method. Some signicant advantages over CMP are (i) high efciency due to high removal rate, (ii) uniform ground surface across the wafer, and (iii) relatively low cost involved in this process.The authors have conducted experiments to compare the over- all performance involved in CMP process with that of the ELID grinding process. The ELID grinding operation was carried out on a Computer Numeric Control (CNC) machining center (Fig. 9). The optimum conditions were determined by observing the effects of various parameters related to ELID grinding and then proper conditions for better results were selected.The ELID grinding parameters for wafer machining are as follow: feed speed 100 mm/min, wheel grit 8000 (grit size 1.76mm), spindle speed 500 rpm, depth of cut 1m, ELID power voltage 90 V, max current 10 A.In the grinding of silicon wafer, the material removal rate is remarkably high and typically 6.596 mm3/min can be achieved. The wheel wear rate is negligible. After grinding two wafers to 195m thickness, there is no variation in the thickness of the grinding wheel. The ground surface is perfectly ductile and mirror like nish could be achieved as shown in Fig. 10.Fig. 6. Limitation in ELID grinding. Fig. 7. Effect of dressing current condition.Fig. 8. A spheric microlens by ELID grinding (5 mm diameter)Fig. 9. Experimental setup for ELID grinding of silicon wafer.Fig. 10. Mirror nished silicon surface.2.2. Nanosurface generation by ultra precision machining2.2.1. Ultra precision machining using single point diamond tool (SPDT)Ultra precision machining is a technique which removes materials from a few microns to sub-micron level to achieve ductile mode machining on hard-to-machine materials such as electro-less nickel plating, silicon, quartz, glass and ceramics with no subsurface defects. Such a machining process is able to achieve mirror surface nish of less than 10 nm and form error of less than 1m easily. If properly applied to a specic range of diamond turn-able materials, the process is far superior to grinding and polishing where shape control is more difcult and processing time is longer.An important factor to achieve ultra precision machining is a machine tool capable of moving in high accuracy at nanometer resolution. Necessary features for such a machine tool includes stiffness for vibrational stability, air bearing spindles with low run-outs, straight square ways and closed loop controller using nanometer resolution feedback. One such machine used in the Advanced Manufacturing Laboratory of NUS is the Toshiba ULG100C (H3) ultra precision machine. Another important factor is to employ high quality tools made of single crystal diamond be it natural or articial. The advantages of single crystal diamond cutter include high hardness and wear resistance, good thermal conductivity for heat removal during machining, and it is possible to achieve sharp cutting edge radius of 20 nm for nanometric level cutting. Other important factors to consider include cutter geometry, tool wear, coolant supply, cutting conditions, and the characteristics of the material being machined. The employment of SPDT in a turning setup is commonly referred to as diamond turning as shown in the machining setup in Fig. 11.Fig. 11. Face turning setup.Fig. 12. Flank (a) and rake (b) face wear after cutting distance of 93.6 km on EN of 5.7% P (w/w).2.2.2. Diamond turning of electro-less nickel plated molding diesA major application of the ultra precision machining technology is for the diamond turning of electro-less nickel plated molding dies for plastic optical parts such as LCD or projection TV. However, a big challenge posed is the short tool life of diamond cutters and polishing process is required after diamond turning. This is not desired as the form error of the polished surface is inferior to that of the diamond-turned surface. Hence, it is important to maintain only the turning process for such molds and the goal of this project is improving diamond cutting tool life by optimizing material characteristics of electro-less nickel, design of the diamond cutting tools and the machining conditions. At the Advanced Manufacturing Laboratory of NUS, a project was undertaken in collaboration with PERL of Hitachi Ltd., Japan to study into this problem.The process for diamond turning of electroless nickel molding dies has been established and surface roughness of less than 6 nm (Ra) has been achieved. Major factors affecting the wear of diamond cutter have been established; namely (a) the electro-less nickel plating composition, (b) the crystal orientation of the diamond cutter, (c) the types of diamond employed (articial or natural), and (d) the rake angle of the diamond cutters. Taking these into consideration, a long cutting distance of 200 km has been achieved and still maintaining mirror surface nish quality of 0.12 mm Ry. The following subsections show the major ndings of the project undertaken.2.2.2.1. Investigating cutter performance for different electro-less nickel plating (EN) compositions.In diamond turning of electro-less nickel plating, the composition of nickel and phosphorus in the electro-less nickel has signicant inuence on its machinability for two reasons. Firstly, elements like nickel and iron work as catalysts, which promote the diamondgraphite transformation 10, hence a greater amount nickel compared to phosphorus will lead to greater diamond cutter wear. Secondly, the phosphorus content in electro-less nickel signicantly affects its structure and hardness11. Electro-less nickel with lower phosphorus content tend to be more brittle and harder, hence making it harder to machine. Experimental cuts were made on work-pieces of 5.7% and 11.5% (w/w) phosphorus to see the cutter performance, hence establishing the preferred electro-less nickel composition as detailed by Pramanik et al. 12.The quantitative comparisons of cutting tool performance in terms of surface nish and wear with cutting distance for different phosphorus content have been presented in Figs. 1215. It is very clear that rate of wear is very small and almost constant for 11.5% (w/w) phosphorus content, hence maintaining good surface nish. On the other hand, tool wear was so high when machining electro-less nickel with 5.7% (w/w) phosphorus content that machining had to be stopped after cutting around 100 km. The severe wear is obvious when comparing the micro- graphs (Figs. 12 and 13) of the cutters that were used to machined electroless with different phosphorus content. The phosphorus in electro-less nickel not only affects its hardness and material structure, but also to serve as a lubricant to aid the machining process. Though electroless nickel with lower phosphorus content is harder and brittle, no brittle fracture was noticed during machining. So phosphorus content plays some more roles in chemical property of electro-less nickel and tool wear, from experimental results it can be assumed that phosphorus mitigates the catalytic action of nickel for promoting diamondgraphite transformation. It is clear that phosphorus protects the cutter from damage and facilitates the machinability of electro-less