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毕业设计（论文）报告纸
LATHES
The basic machines that are designed primarily to do turning, facing and boring are called lathes.Very little turning is done on other types of machine tools, and nine can do it with equal facility.Because lathe can do boring, facing, drilling, and reaming in addition to turning, their versatility permits several operations to be performed with a single setup of the workpiece.This accounts for the fact that lathes of various types are more widely used in manufacturing than any other machine tool.
Lathes in various forms have existed for more than two thousand years.Modem lathes date from about 1797, when Henry Maudsley developed one with a leadscrew.It provided controlled, mechanical feed of the tool.This ingenious Englishman also developed a change-gear system that could connect the motions of the spindle and leadscrew and thus enable threads to be cut.
Lathe Construction.The eential components of a lathe are depicted in the block diagram of Fig.15-1.These are the bed, headstock aembly, tailstock aembly, carriage aembly, quick-change gear box, and the leadscrew and feed rod.
The bed is the backbone of a lathe.It is usually made of well-normalized or aged gray or nodular cast iron and provides a heavy, rigid frame on which all the other basic components are mounted.Two sets of parallel, longitudinal ways, inner and outer, are contained on the bed, usually on the upper side.Some makers use an inverted V-shape for all four ways, whereas others utilize one inverted V and one flat way in one or both sets.Because several other components are mounted and/or move on the ways they must be made with precision to aure accuracy of alignment.Similarly, proper precaution should be taken in operating a lathe to aure that the ways are not damaged.Any inaccuracy in them usually means that the accuracy of the entire lathe is destroyed.The ways on most modern lathes are surface hardened to offer greater resistance to wear and abrasion.
The headstock is mounted in a fixed position on the inner ways at one end of the lathe bed.It provides a powered means of rotating the work at various speeds.It consists, eentially, of a hollow spindle, mounted in accurate bearings, and a set of transmiion gears---similar to a truck transmiion---through which the spindle can be rotated at a number of speeds.Most lathes provide from eight to eighteen speeds, usually in a geometric ratio, and on modern lathes all the
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毕业设计（论文）报告纸
speeds can be obtained merely by moving from two to four levers.An increasing trend is to provide a continuously variable speed range through electrical or mechanical drives.
Because the accuracy of a lathe is greatly dependent on the spindle, it is of heavy construction and mounted in heavy bearings, usually preloaded tapered roller or ball types.A longitudinal hole extends through the spindle so that long bar stock can be fed through it.The size of this hole is an important size dimension of a lathe because it determines the maximum size of bar stock that can be machined when the material must be fed through the spindle.
The inner end of the spindle protrudes from the gear box and contains a means for mounting various types of chucks, face plates, and dog plates on it.Whereas small lathes often employ a threaded section to which the chucks are screwed, most large lathes utilize either cam-lock or key-drive taper noses.These provide a large-diameter taper that aures the accurate alignment of the chuck, and a mechanism that permits the chuck or face plate to be locked or unlocked in position without the neceity of having to rotate these heavy attachments.
Power is supplied to the spindle by means of an electric motor through a V-belt or silent-chain drive.Most modern lathes have motors of from 5 to 15 horsepower to provide adequate power for carbide and ceramic tools at their high cutting speeds.
The tailstock aembly consists, eentially, of three parts.A lower casting fits on the inner ways of the bed and can slide longitudinally thereon, with a means for clamping the entire aembly in any desired location.An upper casting fits on the lower one and can be moved transversely upon it on some type of keyed ways.This transverse motion permits aligning the tailstock and headstock spindles and provides a method of turning tapers.The third major component of the aembly is the tailstock quill.This is a hollow steel cylinder, usually about 2 to 3 inches in diameter, that can be moved several inches longitudinally in and out of the upper casting by means of a handwheel and screw.The open end of the quill hole terminates in a Morse taper in which a lathe center, or various tools such as drills, can be held.A graduated scale, several inches in length, usually is engraved on the outside of the quill to aid in controlling its motion in and out of the upper casting.A locking device permits clamping the quill in any desired position.
The carriage aembly provides the means for mounting and moving cutting tools.The
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毕业设计（论文）报告纸
carriage is a relatively flat H-shaped casting that rests and moves on the outer set of ways on the bed.The transverse bar of the carriage contains ways on which the cro slide is mounted and can be moved by means of a feed screw that is controlled by a small handwheel and a graduated dial.Through the cro slide a means is provided for moving the lathe tool in the direction normal to the axis of rotation of the work.
On most lathes the tool post actually is mounted on a compound rest.This consists of a base, which is mounted on the cro slide so that it can be pivoted about a vertical axis, and an upper casting.The upper casting is mounted on ways on this base so that it can be moved back and forth and controlled by means of a short lead screw operated by a handwheel and a calibrated dial.
Manual and powered motion for the carriage, and powered motion for the cro slide, is provided by mechanisms within the apron, attached to the front of the carriage.Manual movement of the carriage along the bed is effected by turning a handwheel on the front of the apron, which is geared to a pinion on the back side.This pinion engages a rack that is attached beneath the upper front edge of the bed in an inverted position.
To impart powered movement to the carriage and cro slide, a rotating feed rod is provided.The feed rod, which contains a keyway throughout most of its length, paes through the two reversing bevel pinions and is keyed to them.Either pinion can be brought into mesh with a mating bevel gear by means of the reversing lever on the front of the apron and thus provide “forward” or “reverse” power to the carriage.Suitable clutches connect either the rack pinion or the cro-slide screw to provide longitudinal motion of the carriage or transverse motion of cro slide.
For cutting threads, a second means of longitudinal drive is provided by a lead screw.Whereas motion of the carriage when driven by the feed-rod mechanism takes place through a friction clutch in which slippage is poible, motion through the lead screw is by a direct, mechanical connection between the apron and the lead screw.This is achieved by a split nut.By means of a clamping lever on the front of the apron, the split nut can be closed around the lead screw.With the split nut closed, the carriage is moved along the lead screw by direct drive without poibility of slippage.
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毕业设计（论文）报告纸
Modern lathes have a quick-change gear box.The input end of this gear box is driven from the lathe spindle by means of suitable gearing.The output end of the gear box is connected to the feed rod and lead screw.Thus, through this gear train, leading from the spindle to the quick-change gear box, thence to the lead screw and feed rod, and then to the carriage, the cutting tool can be made to move a specific distance, either longitudinally or transversely, for each revolution of the spindle.A typical lathe provides, through the feed rod, forty-eight feeds ranging from 0.002 inch to 0.118 inch per revolution of the spindle, and, through the lead screw, leads for cutting forty-eight different threads from 1.5 to 92 per inch.On some older and some cheaper lathes, one or two gears in the gear train between the spindle and the change gear box must be changed in order to obtain a full range of threads and feeds.
CUTTING TOOL
Shape of cutting tools, particularly the angles, and tool material are very important factors.The purpose of this unit is to introduce the cutting tool geometry and tool materials.Cutting Tool Geometry
Angles determine greatly not only tool life but finish quality as well.General principles upon which cutting tool angles are based do not depend on the particular tool.Basically, grinding wheel are being designed.Since, however, the lathe (turning) tool, depicted in Fig.14-1, might be easiest to visualize, its geometry is discued.
Tool features have been identified by many names.The technical literature is full of confusing terminology.Thus in the attempt to clear up existing disorganized conceptions and nomenclature, the American Society of Mechanical Engineers published ASA Standard B5-22-1950.what follows is based on it.
A single-point tool is a cutting tool having one face and one continuous cutting edge.Tool angles identified in Fig.14-2 are as follows: (1) Back-rake angle, (2) Side-rake angle, (3) End-relief angle (4) End-relief angle (5) Side-relief angle (6) End-cutting-edge angle, (7) Side-cutting-edge angle, (8) Nose angle, (9) Nose radius.
Tool angle 1, on front view, is the back-rake angle.It is the angle between the tool face and a line parallel to the base of the shank in a longitudinal plane perpendicular to the tool base.Then this angle is downward from front to rear of the cutting edge, the rake id positive; when upward
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毕业设计（论文）报告纸
from front to back, the rake is negative.This angle is most significant in the machining proce, because it directly affects the cutting force, finish, and tool life.
The side-rake angle, numbered 2, measures the slope of the face in a cro plane perpendicular to the tool base.It, also, is an important angle, because it directs chip flow to the side of the tool post and permits the tool to feed more easily into the work.
The end-relief angle is measured between a line perpendicular to the base and the end flank immediately below the end cutting edge; it is numbered 3 in the figure.It provides clearance between work and tool so that its cut surface can flow by with minimum rubbing against the tool.To save time, a portion of the end flank of the tool may sometimes be left unground, having been previously forged to size.In such case, this end-clearance angle, numbered 4, measured to the end flank surface below the ground portion, would be larger than the relief angle.
Often the end cutting edge is oblique to the flank.The relief angle is then best measured in a plane normal to the end cutting edge perpendicular to the base of the tool.This clearance permits the tool to advance more smoothly into the work.
The side-relief angle, indicated as 5, is measured between the side flank, just below the cutting edge, and a line through the cutting edge perpendicular to the base of the tool.This clearance permits the tool to advance more smoothly into the work.
Angle 6 is the end-cutting-edge angle measured between the end cutting edge and a line perpendicular to the side of the tool shank.This angle prevents rubbing of the cut surface and permits longer tool life.
The side-cutting-edge angle, numbered 7, is the angle between the side cutting edge and the side of the tool shank.The true length of cut is along this edge.Thus the angle determines the distribution of the cutting force.The greater the angle, the longer the tool life; but the poibility of chatter increases.A compromise must, as usual, be reached.
The nose angle, number 8, is the angle between the two component cutting edges.If the corner is rounded off, the arc size is defined by the nose radius 9.the radius size influences finish and chatter.Cutting Tool Materials
A large number of cutting tool materials have been developed to meet the demands of high
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毕业设计（论文）报告纸
metal-removal rates.The most important of these materials and their influence on cutter design, are described below.
High Carbon Steel.Historically, high carbon steel was the earliest cutting material used industrially, but it has now been almost entirely superseded since it starts to temper at about 220℃ and this irreversible softening proce continues as temperature increases.Cutting speeds with carbon steel tools are therefore limited to about 0.15m/s (30ft/min) when cutting mild steel, and even at these speeds a copious supply of coolant is required.
High-speed Steel.To overcome the low cutting speed restriction imposed by plain carbon steels, a range of alloy steels, known as high-speed steels, began to be introduced during the early years of this century.The chemical composition of these steels varies greatly, but they basically contain about 0.7% carbon and 4% chromium, with addition of tungsten, vanadium, molybdenum and cobalt in varying percentages.They maintain their hardne at temperatures up to about 600℃, but soften rapidly at cutting speeds in exce of 1.8m/s (350ft/min), and many cannot succefully cut mild steel faster than 0.75m/s (150ft/min).
Sintered Carbides.Carbide cutting tools, which were developed in Germany in the late 1920s, usually consist of tungsten carbide or mixtures of tungsten carbide and titanium or tantalum carbide in powder form, sintered in a matrix of cobalt or nickel.Because of the comparatively high cost of this tool material and its low rupture strength, it is normally produced in the form of tips which are either brazed to a steel shank or mechanically clamped in a specially designed holder.Mechanically clamped tool tips are frequently made as throwaway inserts.When all the cutting edges have been used the inserts are discarded, ad regrinding would cost more than a new tip.
The high hardne of carbide tools at elevated temperatures enables them to be used at much faster cutting speeds than high-speed steel (of 3-4m/s（600-800ft/min）when cutting mild steel).They are manufactured in several grades, enabling them to be used for most machining applications.Their earlier brittlene has been largely overcome by the introduction of tougher grades, which are frequently used for interrupted cuts including many arduous face-milling operations.
Recently, improvements have been claimed by using tungsten carbide tools coated with
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毕业设计（论文）报告纸
titanium carbide or titanium nitride (about 0.0005mm coating thickne).These tools are more resistant to wear than conventional tungsten carbide tools, and the reduction in interface friction using titanium nitride results in a reduction in cutting forces and in tool temperatures.Hence, higher metal removal rates are poible without detriment to tool life or alternatively longer tool lives could be achieved at unchanged metal removal rates.
The uses of other forms of coating with aluminum oxide and polycrystalline cubic boron nitride are still in an experimental stage, but it is likely that they will have important applications when machining cast iron, hardened steels and high melting point alloys.
Ceramics.The so-called ceramic group of cutting tools represents the most recent development in cutting tool materials.They consist mainly of sintered oxides, usually aluminum oxide, and are almost invariably in the form of clamped tips.Because of the comparative cheapne of ceramic tips and the difficulty of grinding them without causing thermal cracking, they are made as throw-away inserts.
Ceramic tools are a post-war introduction and are mot yet in general factory use.Their most likely application is in cutting metal at very high speeds, beyond the limits poible with carbide tools.Cramics resist the formation of a built-up edge and in consequence produce good surface finishes.Since the present generation of machine tools is designed with only sufficient power to exploit carbide tooling, it is likely that, for the time being, ceramics will be restricted to high-speed finish machining where is sufficient power available for the light cuts taken.The extreme brittlene of ceramic tools has largely limited their use to continuous cuts, although their use in milling is now poible.
As they are poorer conductors of heat than carbides, temperatures at the rake face are higher than in carbide tools, although the friction force is usually lower.To strengthen the cutting edge, and consequently improve the life of the ceramic tool, a small chamfer or radius is often stoned on the cutting edge, although this increases the power consumption.
Diamonds.For producing very fine finishes of 0.05-0.08um（2-3um) on non-ferrous metals such as copper and aluminum, diamond tools are often used.The diamond is brazed to a steel shank.Diamond turning and boring are eentially finishing operations, as the forces imposed by any but the smallest cuts cause the diamond to fracture or be torn from its mounting.Under
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毕业设计（论文）报告纸
suitable conditions diamonds have exceptionally long cutting lives.
Synthetic polycrystalline diamonds are now available as mechanically clamped cutting tips.Due to their high cost they have very limited applications, but are sometimes used for machining abrasive aluminum-silicon alloys, fused silica and reinforced plastics.The random orientation of their crystals gives them improved impact resistance, making them suitable for interrupted cutting.
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毕业设计（论文）报告纸
车床
用于车外圆、端面和镗孔等加工的机床称作车床。车削很少在其他种类的机床上进行，因为其他机床都不能像车床那样方便地进行车削加工。由于车床除了用于车外圆还能用于镗孔、车端面、钻孔和铰孔，车床的多功能性可以是共建在一次定位安装中完成多种加工。这种是在生产中普遍使用的各种车床比其他种类的机床都要多的原因。
两千多年前就已经有了车床。现代车床可以追溯到大约1797年，那时亨利·莫德斯利发明了一种具有丝杠的车床。这种车床可以控制工具的机械进给。这位聪明的英国人还发明了一种把主轴和丝杠相连的变速装置，这样就可以切削螺纹。
图15-1中标出了车床的主要部件：床身、主轴箱组件、尾架组件、拖板组件、变速齿轮箱、丝杠和光杠。
床身是车床的基础件。它通常是由经过充分正火或时效处理的灰铸铁或者球墨铸铁制成，它是一个坚固的刚性框架，所有其他主要部件都安装在床身上。通常在床身上那个面有内外另组平行的导轨。一些制造厂生产的四个条导轨都采用倒“V”形，而另一些制造厂则将倒“V”形导轨和平面导轨相结合。由于其他的部件要安置在导轨上并（或）在导轨上移动，导轨要经过精密加工，以保证其装配精度。同样地，在操作中应该小心，以避免损伤导轨。导轨上的任何误差，常常会使整个机床的精度遭到破坏。大多数现代车床的导轨要进行变面淬火处理，以减少磨损和擦伤，具有更大的耐磨性。
主轴箱安装在车身一端内导轨的固定位置上。它提供动力，使工件在各种速度下旋转。它基本上有一个安装在精密轴承中的空心主轴和一系列变速齿轮——类似于卡车变速箱所组成，通过变速齿轮，主轴可以在许多种转速下旋转。大多数车床有8～18种转速，一般按等比级数排列。在现代车床上只需扳动2～4个手柄，就能得到全部档位的转速。目前发展的趋势是通过电气的或机械的装置进行无极变速。
由于车床的精度在很大程度上取决于主轴，因此主轴的结构尺寸较大，通常安装在紧密配合的重型圆锥滚子轴承或球轴承中。主轴中有一个贯穿全长的通孔，长棒料可以通过该孔送料。主轴孔的大小是车床的一个重要尺寸，因为当工件必须通过主轴孔供料时，它确定了能够加工棒料毛坯的最大外径尺寸。
主轴的内端从主轴箱中凸出，其上可以安装多种卡盘、花盘和挡块。而小型的车
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毕业设计（论文）报告纸
床常有螺纹截面供安装卡盘之用。很多大车床使用偏心夹或键动圆锥轴头。这些附件组成了一个大直径的圆锥体，以保证对卡盘进行精确地装配，并且不用旋转这些笨重的附件就可以锁定或松开卡盘或花盘。
主轴由电动机经V带或无声链装置提供动力。大多数现代车床都装置有5～15马力的电动机，为硬质合金和金属陶瓷合金刀具提供足够的动力，进行高速切削。
尾座组件主要由三部分组成。底座与床身的内侧导轨配合，并可以子导轨上做纵向移动，底座上有一个可以使整个尾座组件加紧在任意位置上的装置。尾座安装在底座上，可以沿键槽在底座上横向移动，使尾座与主轴箱中的主轴对中并为切削圆锥体提供方便。尾座组件的第三部分是尾座套筒，它是一个直径通常在2～3英寸之间的钢制空心圆柱轴。通过手轮和螺杆，尾座套筒可以在尾座体中纵向移入和移出几英寸。活动套筒的开口一端具有莫氏锥度，可以用于安装顶尖或诸如钻头之类的各种刀具。通常在活动套筒的外表面刻有几英寸长的刻度，以控制尾座的前后移动。锁定装置可以使套筒在所需的位置上夹紧。
拖板组件用于安装和移动切削工具。拖板是一个相对平滑的H形铸件，安装在床身外侧导轨上，并可以在上面移动。大拖板上有横向导轨，使横向拖板可以安装在上面，并通过丝杠使其运动，丝杠由一个小手柄和刻度盘控制。横拖板可以带动刀具垂直于工件的旋转轴线切削。
大多数车床的刀架安装在复式刀座上，刀座上有底座，底座安装在横拖板上，可绕垂直轴和上刀架转动。上刀架安装在底座上，可用手轮和刻度盘控制一个短丝杠使其前后移动。
溜板箱装在大拖板前面，通过溜板箱内的机械装置可以手动和动力驱动大拖板以及动力驱动横拖板。通过转动溜板箱前的手轮，可以手动操作拖板沿床身移动。手轮的另一端与溜板箱背面的小齿轮连接，小齿轮与齿条啮合，齿条倒装在床身前上边缘的下面。
利用光杆可以将动力传递给大拖板和横拖板。光杆上有一个几乎贯穿于整个光杠的键槽，光杠通过两个转向相反并用键连接的锥齿轮传递动力。通过溜板箱前的换向手柄可使啮合齿轮与其中的一个锥齿轮啮合，为大拖板提供“向前”或“向后”的动力。适当的离合器或者齿条小齿轮连接或者与横拖板的螺杆连接，是拖板纵向移动或使横拖板横向移动。
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毕业设计（论文）报告纸
对于螺纹加工，丝杠提供了第二种纵向移动的方法。光杠通过摩擦离合器驱动拖板移动，离合器可能会产生打滑现象。而丝杠产生的运动是通过滑板箱与丝杠之间的直接机械连接来实现的，对于螺母可以实现这种连接。通过溜板箱前面的夹紧手柄可以使对开螺母紧紧包合丝杠。当对开螺母闭合时，可以沿丝杠直接驱动拖板，而不会出现打滑的可能性。
现代车床有一个变速齿轮箱，齿轮箱的输入端有车床主轴通过合适的齿轮传动来驱动。齿轮箱的输出端与光杠和丝杠连接。主轴就是这样通过齿轮传动链驱动变速齿轮箱，在带动丝杠和光杠，然后带动拖板，刀具就可以按主轴的转数纵向地或横向地精确移动。一台典型的车床的主轴每旋转一圈，通过光杠可以获得从0.002到0.118英寸尺寸范围内的48种进给量；而使用丝杠可以车削从1.5到92牙/英寸范围内的48种不同螺纹。一些老式的或价廉的车床为了能够得到所有的进给量和加工出多有螺纹，必须更换主轴和变速箱之间的齿轮系中的一个或两个齿轮。
金属切削刀具
刀具的形状（特别是其角度）和材料是刀具的两个非常重要的因素。本文向大家介绍刀具的几何参数和刀具材料。
刀具几何参数
刀具的角度不仅在很大程度决定了刀具的寿命，而且也决定加工的表面质量。刀具角度设计的一般性原则不因某种特殊刀具而变。车刀、铣刀、钻头甚至是砂轮的设计，所要考虑的因素基本相同。图14.1所示的车刀外形易于观察，我们即以此为例来讨论刀具的几何参数。
刀具特征参数名目繁多，技术文献中术语使用也很混乱。为了澄清已有的混乱的概念和术语，美国机械工程师协会颁布了ASA标准B5-22—1950，本文的术语即以此为依据。
单尖刀具是指只有一个前刀面和一条连续切削刃的刀具。图14-2所示各个角度定义如下：
主视图中的角度1为背前角，它是在垂直于刀具基面的纵向剖面内的平行于刀柄的一条直线与刀面之间的夹角。如该角后倾，则为正角，否则为负角。背前角对加工过程影响很大，它直接影响刀具的切削力、表面光洁度以及刀具耐用度。
角度2为侧前角，它是刀具前刀面在垂直于刀具基面的横向剖面内的倾斜角。侧
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毕业设计（论文）报告纸
前角也是一个重要的几何角度，它能把切屑引向刀架的一侧，并能使进给更加容易。
端后角是刀具基面的垂线与紧靠端切削刃下的断后刀面之间的夹角，即图中角度3。它确保工件和刀具之间有间隙使得切屑经过刀具时摩擦最小。为了节省磨刀时间，刀具段后刀面的一部分有时可以直接锻造成形，而不需要进行磨削。在这种强况下，从断后刀面刃磨部位下量出的角度（角度4）比端后角大。
通常端切削刃与端后刀面是斜交的，因此，端后角最好是在于端切削刃相垂直的平面内进行测量。后角也可用刀具的侧面和端面的视图来表示。
角度5表示侧后角，它是端切削刃下面的侧后刀面与通过切削刃并垂直于刀具基面的直线之间的夹角。侧后角能使刀具更平稳的切入工件。
角度6为端切削刃角，它是端切削刃和垂直于刀具柄侧面的直线之间的夹角。该角可减少刀具和已加工表面之间的摩擦，延长刀具的使用寿命。
角度7为侧切削刃角，它是测切削刃和刀柄侧面之间的夹角。由于刀具切削长度是沿着此切削刃的，因此，侧切削刃角决定了切削力的分布。该角度越大，刀具寿命越长，但颤振的可能性也随之增加。设计时，这两方面的因素都要兼顾。
角度8为刀尖角，它是两条切削刃之间的夹角。刀尖采用圆弧过渡时，圆弧的尺寸可用弧半径9来表示。刀尖圆弧半径的尺寸对表面光洁度及颤振有影响。
刀具材料
已有许多刀具材料能满足高金属切削率的要求。下面讨论最重要的几种材料和它们对刀具设计的影响。
1.高碳钢：才刀具历史上，高碳钢是最早用于工业上的刀具材料，但目前已几乎全部被废弃不用了，因为它在220°C左右开始回火，而且这种软化过程随着温度的升高而继续。因此，在切削低碳钢时，高碳钢刀具的切削速度限于大约0.15mm/s(30ft/min)，即使在这种速度时也要连续供应切削液。
2.高速钢：为克服普通碳素钢切削速度较低的特点，本世纪初，几种称为高速钢的合金钢开始用于金属切削。这些钢的化学成分差别很大，但基本上都含有大约0.7%碳和4%铬，另外还有比例不一样的钨、钒、钼和鈷。它们在高达600°C时仍能保持硬度，但在更高温度下会迅速软化。实验表明：高速钢切削低碳钢时，如速度超过1.8m/s(350ft/min),就会很快失效，而且许多高速钢材料在速度超过0.75m/s(150ft/min)时，就不能成功切削低碳钢。
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毕业设计（论文）报告纸
3.硬质合金：这是20世纪20年代晚期德国出现的硬质合金刀具，通常是将碳化钨或碳化钨和碳化钛或碳化钽的混合物以粉末形式沉积在鈷或镍的基体上。因为较高成本和较低的断裂强度，它们通常以刀片形式铜焊在钢质刀柄上或机械夹持在特质夹具撒上。机夹形式刀头经常做成不重磨形式，当所有刀刃都用废时，就将刀片丢弃，因为重磨成本比新刀片的成本高得多。
硬质合金刀具在高温时具有高硬度，故它们的切削速度比高速钢高得多，切削低碳钢时为3～4m/s(600-800ft/min),它们有几种牌号专用于大多数加工场合。韧性更高的硬质合金大大克服了早期产品的脆性，故也能用于断续切削，包括许多费力的面铣加工。 最近，已经出现碳化钛或氮化钛涂层碳化钨刀具（涂层大约厚0.0005mm）。这些刀具比普通碳化钨硬质合金刀具更耐磨，使用氮化钛涂层界面摩擦力减小，导致切削力和刀具温度降低。因此，不降低刀具寿命就可得到较高的金属切削率，或不改变金属切削率而延长刀具寿命。
使用氧化铝涂层和多晶氮化硼的其他涂层尚处于实验阶段，但它们很可能在加工铸铁、淬硬钢和高熔点合金时有重要应用。
4.陶瓷：所谓的陶瓷刀具代表了刀具材料的最新进展，它们主要由烧结氧化物（通常是氧化铝）组成，而且几乎不变地做成夹持刀片。因为陶瓷刀片较便宜，而且刃磨时易引起热脆裂，所以都做成不重磨刀片。
陶瓷刀具是战后出现的，还没有在工厂里得到普遍应用。它们大都应用于高速切削中。陶瓷刀具能抑制积屑瘤的形成，能形成好的表面光洁度。因为现代机床的设计功率只能适合硬质合金刀具，目前，陶瓷只限于告诉精加工，此时，机床功率足够进行轻加工。陶瓷刀具特别脆，尽管目前已能进行铣削，陶瓷刀具主要还是限于连续切削。
陶瓷的热传导性比硬质合金差，因此，尽管前刀面上的摩擦力通常较低，但其前刀面的温度比硬质合金的要高得多。为了强化切削刃，进而改进刀具的寿命，经常在切削刃上做成一个小倒棱或圆弧，虽然这样做会增加功率消耗。
5.金刚石：金刚石刀具常用于加工有色金属如铜和铝，可得0.05～0.08um（2~3um）j极高的光洁度。金刚石用铜焊焊接在碳钢刀柄上。金刚石车削和镗孔是基本的精加工，因为任何（即使最轻）粗切削产生的李也会导致金刚石破裂或脱落。在适合的条件下，金刚石切削寿命最长。
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毕业设计（论文）报告纸
合成多晶金刚石目前已被用于机夹刀片上，因其成本太高，目前应用很少，但有时用于加工有磨蚀作用的铝、硅合金，熔融石英和增强塑料，随意的晶体取向改善了它们的冲击抗力，使它们适合断续切削。
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