外文翻譯--切削側(cè)表面刀具的磨損高速干切削

1、<p><b>　　附錄1 外文譯文</b></p><p><b>　　第四章</b></p><p>　　切削側(cè)表面刀具的磨損高速干切削</p><p><b>　　4.1前言</b></p><p>　　許多不同類型的切削刀具都存在著不同程度的磨損，無(wú)論是在側(cè)

2、面、凹面或凸面。 側(cè)面磨損技術(shù)源于平面技術(shù)在新興邊緣摩擦工作面的發(fā)展；主要原因是摩擦表面的數(shù)字顯示見圖4-1。它可以測(cè)量側(cè)面磨損的寬度(VB). 對(duì)于凹面磨損來說由于存在磨粒磨損及其擴(kuò)展于黏附。因此凹面磨損需測(cè)量凹陷的深度(KT)。凸面磨損與側(cè)面磨損的原理基本相同。一般經(jīng)常用到的是磨損寬度VB和凹陷深度KT(見圖4-2)因?yàn)樗麄兛梢员容^清楚的反映出加工工件的路徑。然而,凸面則顯得更難以測(cè)量。在機(jī)械工程發(fā)展的過程中側(cè)面磨損被廣泛的用于大量

3、測(cè)量磨損的標(biāo)準(zhǔn)。</p><p>　　圖4-2顯示了機(jī)械磨損的結(jié)果，這表明了側(cè)面磨損技術(shù)標(biāo)志著一個(gè)新的切削時(shí)代的到來。最初的高速磨損經(jīng)常發(fā)生在切削過程的開始階段。第二個(gè)區(qū)域也是比較好的一個(gè)區(qū)域它處于一個(gè)穩(wěn)定或接近穩(wěn)定的磨損率，其磨損率主要取決于切削速度和切削刃。第三個(gè)區(qū)域也是最后一個(gè)區(qū)域，在這個(gè)區(qū)域里磨損率將迅速增長(zhǎng)他將導(dǎo)致切削刃毀滅性的破壞。對(duì)這一現(xiàn)象的解釋是,側(cè)面與工作面的摩擦而導(dǎo)致溫度的升高，從而引起連鎖反

4、應(yīng)使得溫度迅速升高。</p><p><b>　　4.1.1碳化鐵</b></p><p>　　自從碳化鐵被用于刀具的原材料以來它就大量的作為刀具生產(chǎn)的原料。這種材料的制作是通過粉末冶金技術(shù)的微粒燒結(jié)和加如金屬粘合擠而成的高硬度碳化物。與高速鋼相比，這種碳化鐵提供了較好的硬度和在較高溫度下的熱化學(xué)穩(wěn)定性。作為金屬粉末產(chǎn)品，這種碳化鐵可以生產(chǎn)出不同檔次的產(chǎn)品以應(yīng)用于不同

5、領(lǐng)域。這種技術(shù)可以加工各種不同幾何形狀的工件，當(dāng)然也可以用特制的刀具夾頭或較昂貴的黃銅手柄放在上面。這種化學(xué)膠結(jié)碳化物的組成通常包括碳化鎢(WC)，碳化鈦(TiC)和碳化鉭(TaC)且用鈷作為粘合擠。對(duì)于上述化學(xué)物質(zhì)每個(gè)公司都有自己的混合比例。就碳化鐵的機(jī)械特性來說，如可延展性和韌性取決于其中所含碳化物的等級(jí)和密度。此外,碳化鐵的硬度及抗壓強(qiáng)度在1100°C時(shí)如能達(dá)到800 MPa則TiC的含量將達(dá)到12%，如要使其硬度在80

6、0 °C達(dá)到1.5GPa時(shí)則合金的比例分配將是TiC19%，TaC16%和Co9.5%。</p><p>　　圖4-1 刀具的磨損</p><p>　　圖4-2 切削過程中側(cè)面的磨損狀況</p><p><b>　　4.2 涂層</b></p><p>　　從70年代初涂層技術(shù)開始引進(jìn)以來導(dǎo)致了硬質(zhì)合金涂層生產(chǎn)

7、的極大提高。此后這種涂層技術(shù)幾乎應(yīng)用于各種切割刀具。涂層就像一堵屏障以防止切削碎片和原料的工作表面發(fā)生相互作用。到目前為止已經(jīng)開發(fā)出了各種不同類型的涂層材料，包括氮化鈦（TiN）,碳化鈦（TiC），三氧化二鋁（AL2O3 ）和氮化鋯（ZrN）。一般來說,其硬度高于200VDH并在鐵的參合下溶解性極低。在機(jī)械設(shè)備中的鋼和鐵都存在銹蝕和脫落的問題，這些涂層能夠使延長(zhǎng)他們的使用壽命。但是涂層技術(shù)并不能應(yīng)用于防止切削刀具的折斷與破損。</

8、p><p>　　在刀具上應(yīng)用涂層TiN,TiCN和A12O3顯示了其具有阻礙和降低刀具表面的磨損的作用。以下是常用的涂層技術(shù)：</p><p><b>　　4.2.1單層涂層</b></p><p>　　這種技術(shù)是將TiC以化學(xué)蒸汽的形式沉積到硬質(zhì)合金表面上而提出的。然而,在使用這個(gè)過程中的缺點(diǎn)是硬質(zhì)合金上的涂層會(huì)帶走金屬表面的碳。這將打破化學(xué)平衡

9、和刀具成分的變化從而使涂層和刀具本體的分界層變的比較脆，這將使刀具在切入工件時(shí)在刀具邊緣出現(xiàn)容易斷裂的結(jié)果。</p><p><b>　　4.2.2多層涂層</b></p><p>　　這種類型涂層技術(shù)的提及被稱為“三明治”涂層，根據(jù)涂層材料的不同而有不同的組合最多可顯示多達(dá)8層以上涂層。這種“三明治”涂層技術(shù)的最后一層厚度能達(dá)到10-15微米，它遠(yuǎn)遠(yuǎn)大于進(jìn)行涂層過程

10、中的第一層涂層。但是，第一涂層將是最佳結(jié)合性能單一涂層。</p><p>　　多層涂層技術(shù)一般由TiN/TiCN/ AL2O3涂層，TiN/ AL2O3/ TiC / TiCN涂層或者它們之間的組合。另一方面，涂層中也引進(jìn)了一些張力與壓力的概念以提高刀具抗拒機(jī)械沖擊的過程。</p><p>　　在側(cè)面磨損與凹面磨損之間有著不同類型的涂層。TiN涂層用于凹面的抗磨性比TiC涂層好而在側(cè)面上用

11、TiC涂層將比TiN涂層的抗磨性好。但是，在側(cè)面或凹面上采用涂層AL2O3的抗磨效果幾乎是相同的，就像在側(cè)面上采用碳化物涂層及在凹面上采用氮化物涂層一樣。最近報(bào)道顯示，塑料在抗變形能力上將比其他材料要優(yōu)越的多因而在抗磨性上有取代鋁化物涂層的趨勢(shì)。</p><p>　　4.3干燥條件下機(jī)械磨損的研究</p><p>　　關(guān)于刀具的使用壽命實(shí)驗(yàn)數(shù)據(jù)在第三章已加以論述，機(jī)械磨損的研究將在4.4節(jié)

12、、4.5節(jié)和4.6節(jié)加以論述。通過這幾節(jié)的論述將加深對(duì)涂層技術(shù)研究的理解提供有益的啟示，優(yōu)化機(jī)械操作和對(duì)涂層材料及涂層技術(shù)的改進(jìn)提供必要的知識(shí)。因?yàn)槟ハ黝愋偷姆诸愂歉鶕?jù)切削速度來進(jìn)行的，所以對(duì)微小磨削非傳統(tǒng)切削速度（即HSM）的研究將是非常必要的。通過這次實(shí)驗(yàn)將首次對(duì)磨削壽命及高速干切削條件下的微型機(jī)械磨削進(jìn)行研究。對(duì)于非傳統(tǒng)切削速度的重要性是他能縮短生產(chǎn)時(shí)間、增加盈利及減少機(jī)械故障。</p><p>　　4.4

13、碳化鐵機(jī)械磨損的實(shí)驗(yàn)觀察</p><p>　　干燥條件下的機(jī)械切削</p><p>　　在這一節(jié)中將對(duì)碳化鐵刀具切入4140鋼時(shí)的微型機(jī)械磨削進(jìn)行實(shí)驗(yàn)和觀察。根據(jù)圖4-3A顯示切削刀具在達(dá)到最大磨損極限時(shí)的切削速度通常是180m/min。它顯示了滑移磨損出現(xiàn)在刀具工作表面的側(cè)面位置，即滑移產(chǎn)生在工件表面和刀具切入的側(cè)面?？梢钥闯鲈趥?cè)面磨損中切入深度達(dá)到最大時(shí)的磨削深度。然而將側(cè)面進(jìn)行放大1

14、500倍后，如圖4-3B，則能看見微小的滑痕。在對(duì)鎢化鐵刀具進(jìn)行實(shí)驗(yàn)時(shí)其結(jié)論也幾乎是相同的。隨著切削速度的增加，在切削速度達(dá)到180m/min時(shí)溫度可增加到1115℃；從而導(dǎo)致硬度的急劇下降。</p><p>　　圖4-3B顯示了機(jī)械磨損的微小滑痕，這在鈷作為切入材料的粘合劑時(shí)得到了證實(shí)，碳的顆粒將在側(cè)面上產(chǎn)生而粘在粘合劑上。因此，它的結(jié)論是在切削速度達(dá)到180m/min時(shí)，滑移和微小滑痕都將出現(xiàn)。</p&

15、gt;<p>　　圖4-4A顯示了在干燥條件下切入時(shí)切削速度達(dá)到150m/min的滑移磨損現(xiàn)象。切入側(cè)面的邊緣出現(xiàn)了典型的相互平行的滑移磨損溝槽。它類似于碳化鎢的滑痕半徑30微米。</p><p>　　切削速度在180m/min時(shí)的滑移磨損顯微圖</p><p>　?。˙）切削速度在180m/min時(shí)的滑痕顯微圖</p><p>　　圖 4-3 切速1

16、80m/min時(shí)的放大圖（A）切削速度在180m/min時(shí)的滑移磨損</p><p>　　顯微圖（B）切削速度在180m/min時(shí)的滑痕顯微圖</p><p>　　其它類型的機(jī)械微小磨損的研究也和上述類型相似，如圖4-4B所示，一條微小的滑痕在狹窄的溝槽中顯示。據(jù)報(bào)道同樣類型的磨損現(xiàn)象在陶瓷刀具中也出現(xiàn)過。由于將鈷作為切削刀具的粘合劑則微型溝槽在切削側(cè)表面大量的出現(xiàn)。因此，它的結(jié)論是在15

17、0m/min的切削速度下滑移磨損和微型機(jī)械滑痕都將大量出現(xiàn)。</p><p>　　由于在金屬切削過程中存在多種機(jī)械磨損；包括氧化、擴(kuò)散磨損、腐蝕磨損和疲勞磨損。因磨損的存在則刀具的切削刃是焊接在刀柄上的。因?yàn)榈度信c刀柄之間是焊接為一體的則焊接處刀柄有一缺口以便于安放刀刃。機(jī)械磨損的效力在于刀具表面出現(xiàn)磨粒的硬度。因此刀具切削刃的切削能力與摩擦顆粒的硬度有關(guān)。磨損的擴(kuò)散方向是由刀刃與金屬碎片之間的原子引力來決定的；

18、它將導(dǎo)致原子移動(dòng)的兩個(gè)不同方向。這種方法是通過提高溫度、壓力和接觸時(shí)間來實(shí)現(xiàn)的。機(jī)械疲勞是由于刀刃的連續(xù)壓縮與張力而形成的且刀刃所承受的壓力高于刀刃的機(jī)械強(qiáng)度。另一方面,連續(xù)的降溫和升溫也有可能導(dǎo)致熱疲勞。</p><p>　　切削速度在150m/min時(shí)的滑移磨損顯微圖</p><p>　?。˙）切削速度在150m/min時(shí)的滑痕顯微圖</p><p>　　圖 4

19、-4 切速150m/min時(shí)的放大圖（A）切削速度在150m/min時(shí)的滑移磨損</p><p>　　顯微圖（B）切削速度在150m/min時(shí)的滑痕顯微圖</p><p>　　當(dāng)切削速度在120m/min時(shí)刀具側(cè)表面與工件的接觸方向一般會(huì)出現(xiàn)縱向平行的溝槽。如圖4-5所示在刀具側(cè)表面磨損率較底或較高的區(qū)域都將會(huì)出現(xiàn)沿金屬碎片脫落方向而存在的暗淡脊?fàn)顥l痕。這表明機(jī)械磨損的微小黏附是存在的。在

20、刀具AISI 4340的刀刃中加入鋁的化合物（Al2 03 + TiC ）時(shí)也存在著類似的結(jié)果。隨著切削速度下降,刀刃和切削區(qū)域的溫度也隨之下降。另外隨工件材料脫落的切削碎片的黏性也比高速切削時(shí)底，但也足夠于黏附在刀具切入時(shí)的刀具側(cè)表面。同時(shí)如另一張放大倍數(shù)更高的圖4-6A所示可明顯的看見刀具側(cè)表面摩擦黏附所凸起的脊?fàn)钗?。這種脊?fàn)顥l痕也比其它相進(jìn)的刀具材料所形成的脊?fàn)顥l痕大。隨著刀具側(cè)表面與工件本體之間的連續(xù)摩擦這種粘附在表面的金屬層也

21、會(huì)被摩擦掉。因此，一種新的機(jī)械磨損出現(xiàn)了即微小摩擦磨損。一些低質(zhì)材料也將隨著粘附金屬層的移動(dòng)而帶走。如圖4-6B所示微小摩擦的特征是在表面上出現(xiàn)了微小的孔穴。</p><p>　　當(dāng)切削速度達(dá)到90m/min和60m/min時(shí)則在刀具凹面將出現(xiàn)刃狀。如圖4-7A所示在刀刃上出現(xiàn)了新的刀刃。因?yàn)樵诟稍锏沫h(huán)境下進(jìn)行切削，所以一種無(wú)油潤(rùn)滑且潔凈的高速干切削是可以利用的。這些都是理想情況下在切削凹面上形成的壓力熔接點(diǎn)稱為

22、BUE。它是在切削表面的碎片流動(dòng)速率不是很高的情況下形成的。這顯示了碎片流過凹面部分的流速將隨碎片上層至底層逐級(jí)遞減且最底層黏附在刀具凹面不動(dòng)。這兒有兩種類型的BUE。一種是顯示在速率90和60m/min時(shí)切削材料為4140時(shí)是穩(wěn)定的。這個(gè)跡象闡明了刀具在這兩個(gè)切削速度的壽命最長(zhǎng)。</p><p>　　此外,如圖3-5所示在穩(wěn)定的區(qū)域加大切入長(zhǎng)度并在高速切削時(shí)在刀刃上將不存在壓力熔接點(diǎn)。盡管如此，壓力熔接速率也和

23、切入表面的粘性碎片移動(dòng)速率相等。這就是壓力熔接技術(shù)（BUE）在切速90和60m/min時(shí)穩(wěn)定和連續(xù)的原因。圖4-7B是壓力熔接層放大1000倍的示意圖，它顯示了多層碎片溶解層的重疊。</p><p>　　圖4-5 切速120m/min時(shí)的脊?fàn)顥l痕和滑移磨損顯微圖</p><p>　?。ˋ）切速120m/min時(shí)的微小黏附磨損顯微圖</p><p>　?。˙）切速12

24、0m/min時(shí)黏附層脫落后的微小摩擦磨損顯微圖</p><p>　　圖4-6 切速120m/min時(shí)的側(cè)面區(qū)域顯微圖（A）切速120m/min時(shí)的微小黏</p><p>　　附磨損顯微圖（B）切速120m/min時(shí)黏附層脫落后的微小摩擦磨損顯</p><p><b>　　微圖</b></p><p>　　切速90m/mi

25、n時(shí)刃狀的出現(xiàn)</p><p>　?。˙）切速90m/min時(shí)似刃狀的多層碎片溶解層</p><p>　　圖 4-7 切速90m/min時(shí)的放大圖（A）切速90m/min時(shí)刃狀的出現(xiàn)（B）切</p><p>　　速90m/min時(shí)似刃狀的多層碎片溶解層</p><p><b>　　附錄2 外文原文</b></p&

26、gt;<p>　　CHAPTER IV</p><p>　　TOOL WEAR MECHANISMS ON THE FLANK SURFACE OF CUTTING INSERTS</p><p>　　FOR HIGH-SPEED DRY MACHINING</p><p>　　4.1 Introduction</p><p>

27、　　On the cutting tool many different types of wear mechanisms could take place, on either the flank surface, crater surface, or cutting tool nose [1]. Flank wear takes place by forming a flat surface that develops where

28、the edge rub the newly generated work piece surface; primarily because of the abrasive wear as shown in Figure 4-1. It can be measured by the width of the flank wear land (VB). Crater wear, on the other hand, can be deve

29、loped due to abrasive wear, diffusion and adhesion wear. Crate</p><p>　　Figure 4-2 shows the effect of the wear mechanism, in this case the flank wear on the new cutting edge against time. A rapid initial we

30、ar usually is caused by the break-in that begins the process. The second region on the right is the steady state or nearly steady rate of wear, which depends mainly on the cutting speed or (chip removal) over the cutting

31、 edge. The third and last region is the rapidly increasing wear rate the proceeds to a catastrophic failure of the cutting tool edge. The explana</p><p>　　4.1.1 Uncoated Cemented Carbide</p><p>

32、　　Cemented carbide since its discovery as a cutting tool material has been the most frequently used cutting tool material for high production [1]. This material is fabricated with powder metallurgy technology by sinterin

33、g fine particles of hard carbide in a metal binder. In comparison with high-speed steel, cemented carbide provides a superior hardness chemical stability at elevated temperature. </p><p>　　Figure 4-1 Tool we

34、ar measurement.</p><p>　　Figure 4-2 Wear situations on the flank surface of the cutting tool.</p><p>　　As a metal powder product, the cemented carbide can be produced with different grades for d

35、ifferent applications [2]. Cutting inserts with various geometries can be produced by this technique that either need a special tool holder, or one that can be brazed onto a less expensive shank. The chemical composition

36、 of the cemented carbide, usually includes tungsten carbide (WC), titanium carbide (TiC), and tantalum carbide (TaC) with cobalt as a binder. Each company has its own blending ratio for the</p><p>　　4.2 Coat

37、ings</p><p>　　Since their introduction in early 70's, hard metal coatings have resulted in tremendous increase in production. Since then they have been applied on almost all types of cutting tools. Coati

38、ngs, however, work as a diffusion barrier to prevent interaction between the chip formed and the work piece material. Different types of coating material have been developed in the past, including titanium nitride (TiN),

39、 titanium carbide (TiC), Alumina (AL2O3), and Zirconium nitride (ZrN). In general, their ha</p><p>　　Dearnly and Trent [17] have indicated that the wear resistance of TiN, TiCN, and A12O3 are because of thei

40、r high diffusion resistance on the parts of the tool surface where seizure occurs. The following techniques are commonly used in coating:</p><p>　　4.2.1 Single layer coatings</p><p>　　This techn

41、ique was first presented by placing a single layer of TiC using a chemical vapor deposition onto a substrate of hard metal [1]. However, the disadvantage of using this process in coating hard metal is that some carbon is

42、 taken away from the surface of the metal. This changes the chemical balance and results in a brittle compound at the interface between the coating and the substrate, which makes the insert susceptible to fracture at the

43、 tool edge.</p><p>　　4.2.2 Multiple layer coatings</p><p>　　This type of coatings is referred to as "sandwiched" coatings, in which different combinations of different coating material

44、s are used to display up to eight layers over the substrate. The final thickness from multiple layering processes " sandwiched" can reach 10-15 µm, which is much greater than that of the process trying to

45、produce it by one step. However, this process combines the best properties of single coatings.</p><p>　　Multiple coatings are made up of TiN/TiCN/AL2O3 layers, TiN/AL2O3 l TiC / TiCN or their repetition. On

46、the other hand, the layers also introduce some pre-tensioning in the form of compressive stresses to help the tool withstand the impact of the machining process.</p><p>　　In regard to flank wear and crater w

47、ear there are differences between the different types of coating. TiN is resistant to crater wear than TiC and TiC is more resistant to flank wear than TiN. However, the substrate coated with Alumna AL2O3 has almost the

48、same resistance to flank and crater wear as the inserts coated with carbide and nitride. Dearnly [17] has reported that plastic deformation is the dominant type of wear that takes place on the Alumina coated inserts rath

49、er than diffusion wears.</p><p>　　4.3 Wear Mechanism Study Under Dry Condition</p><p>　　In an attempt to explain the experimental tool life data presented in (Chapter3), wear mechanisms study wa

50、s carried out through out Section 4.4, Section 4.5, and Section 4.6. It will provide a useful insight for understanding the tribological behavior of coating under study, optimizing machining operations, and to provide es

51、sential knowledge to the improvement of coating materials and coatings techniques. Since the wear type is dependent on the cutting speed [2, 18, 19, 22, 26], it is important </p><p>　　4.4 Experimental Observ

52、ations of Wear Mechanisms of Uncoated Cemented CarbideCutting Inserts in Dry Machining</p><p>　　In this section, the experimental findings and observations of micro-wear mechanism with uncoated cemented car

53、bide tool inserts in machining 4140 steel are presented. In light of Figure 4-3A the cutting inserts were used at a cutting speed of 180 m/min after the cutting tool reached the maximum wear limit. It is observed that a

54、sliding wear occurred at the flank surface position at the tool work interface, where sliding occurs between the newly generated work piece material and the flank side of</p><p>　　Micro-abrasion wear mechani

55、sm is revealed from Figure 4-3B, this is justified by the fact that the cobalt is used in the cutting inserts material as a binder [18]. It is worn faster and then the carbide grains protrude out of the flank face. Hence

56、, it is concluded that at this cutting speed (180m/min), both sliding and micro-abrasion wears are activated.</p><p>　　Figure 4-4A was taken for cutting inserts machined at a cutting speed of 150 m/min under

57、 dry conditions. A typical sliding wear at the flank edge of the cutting insert is revealed indicating grooves parallel to the contact direction. It is similar to Koji's [32] findings on Tungsten Carbide inserts in s

58、liding test against diamond pin 30µ radius.</p><p>　　(a) SEM micrographs of (KC313) at 180m/min showing sliding wear</p><p>　　(b) SEM micrographs of (KC313) at 180m/min showing micro-abra

59、sion wear.</p><p>　　Figure 4-3 Magnified images of (KC313) at 180m/min: (a) SEM micrographs of (KC313) at 180m/min showing sliding wear, (b) SEM micrographs of (KC313) at 180m/min showing micro-abrasion wear

60、.</p><p>　　To investigate closely other types of micro-wear mechanisms, a zoom-in view was taken at the surface as shown in Figure 4-4B, a micro-abrasion appeared in the narrow grooves. Chuanzhen [45] report

61、ed the same type of wear when machining Inconel with Ceramic tools. The micro-grooves developed on the flank surface are due mainly to the cobalt used as a binder in this cutting inserts material. Therefore, it is conclu

62、ded that at 150 m/min cutting speed sliding wear and micro-abrasion wear mechanisms </p><p>　　Several wear mechanisms occur during metal cutting; these include oxidation, diffusion wear, abrasive wear, and f

63、atigue wear [26]. Attrition wear leading to a build up edge (BUE), is a localized welding of material during sliding. Since the material is moving, the welding points get broken and take small parts away from the cutting

64、 tool. Abrasive wear is a mechanism of wear where a grinding effect takes place between hard particle and the cutting tool surface under load. The ability of the cutti</p><p>　　The flank surface at 120m/min

65、also has micro-abrasion wear indicated by the longitudinal grooves laid parallel to the contact direction. The flank side has an appearance of dull flat as shown in Figure 4-5 containing ridges lying in the direction of

66、metal chip flow and regions of lower wear rate and others with higher wear rate. This indicates the presence of micro-adhesion wear mechanism. Avila et al [20] recorded similar results when machining AISI 4340 with mixed

67、 alumina tools (Al2 03 + TiC).</p><p>　　SEM micrographs of (KC313) at 150m/min showing sliding wear.</p><p>　　(b)SEM micrographs of (KC313) at 150m/min showing micro- abrasion .</p><p

68、>　　Figure 4-4 Two images of (KC313) at 150m/min:(a) SEM micrographs of (KC313) at 150m/min showing sliding wear, (b) SEM micrographs of (KC313) at 150m/min showing micro- abrasion.</p><p>　　between the fl

69、ank side and the newly generated metal surface. Therefore, a new wear mechanism was activated, which is the micro-attrition wear. Some of the substrate material was plucked away with the removal of adhered metal. As resu

70、lt micro-holes appeared showing the characteristic feature of micro-attrition as shown in Figure 4-6B. This is again is supported by similar results observed by Gu at al [36].</p><p>　　Built up edge (BUE) wa

71、s noticed on the cutting tool crater surface when machined at a cutting speed of 90 m/min and 60 m/min. It's similar to the findings reported by J. Gu [18] in machining resulphurized 0.08 wt-%C steel and C. Lim [31]

72、in testing C5 milling inserts. Figure 4-7A, however, shows a build up edge sticking on the cutting tool edge. Since the machining was carried out at dry conditions, a clean surface was available since no oil lubricant wa

73、s used along with the resultant high heat </p><p>　　In addition, for the tool life Figure 3-5 shows the stable region that extended for longer time than inserts, which were machined at higher cutting speeds

74、and no BUE were observed on their edges. Nonetheless, the fonnation rate of the BUE was equal to the removing rate of the sticking chips from the insert surface. This explains the stability and continuity of the BUE noti

75、ced at 90 and 60 m/min. Figure 4-7B was taken at a magnification of 1000 times by the SEM from the side of BUE, showing multi</p><p>　　4-5 SEM micrographs of (KC313) at 120m/min showing ridges and sliding we

76、ar.</p><p>　　(a) SEM micrographs of (KC313) at 120m/min showing micro-adhesion wear.</p><p>　　SEM micrographs of (KC313) at 120m/min showing</p><p>　　micro-attritionafter the adher

77、ed layer plucked away.</p><p>　　Figure 4-6 A zoom-in view at the flank side at 120(min) showing: (a) SEM. micrographs of (KC313) at 120m/min showing micro-adhesion wear, (b) SEM micrographs of (KC313) at 120

78、m/min showing micro-attrition after the adhered layer plucked away.</p><p>　　SEM micrographs of (KC313) at 90m/min showing build up edge.</p><p>　　SEM micrographs of (KC313) at 90m/min showing t

79、he morphology of the build up edge.</p><p>　　Figure 4-7 Magnified images of (KC313) at 90mlmin: (a) SEM micrographs of (KC313) at 90m/min showing build up edge, (b) SEM micrographs of (KC313) at 90m/min show