41140

Low-alloy carhuri .ing sleets 8620 Same steels as in group following 4140. hut with sulfur added 411 Kl. 411.47. 411 50, 43L.47. 511.32. 86L20. X6L40. 52LIOO 1320. 21 7. 2512. 2515. 2M7. .1115. 3120. < I2V 310. 1.116. 4012. 4017 4023. 4024 4027. 4028, 4118. 4125 4128. 43 7. 4320. 460X. 4615 4617.4620.4621. 4721). 4SI5. 4X17. 4X20. 5015, 5020. < 024. 5120. 61 IS. 6120. 631 . 632V 641V XIIV X6IV X6I7, X622 . 8625. X627 8720. XX22. 9310. 9.315. 94BI5, 94BI Workpiece hardness. III 165-170...

Machines and Accessories

The machines most commonly used for tapping arc drill presses, tapping machines, gang machines, manual or automatic turret lathes, and other multiple-operation machines. Tapping machines are basically drill presses equipped with lead screws, tap holders, and reversing mechanisms. Lead screws or lead-control devices provide a means of regulating the desired feed rate during tapping. The amount of feed per revolution determines the pitch of the tapped thread. Lead screws convert rotary motion...

Through Feed Rolling

In through-feed rolling, the work moves axially through Ihe dies. Through-feed dies are designed with a lead angle generally different from thai of the work, so that the part can feed. The dies are made with a starling taper, so that the thread is formed progressively as the blank feeds through ihe dies. I'hc finish end of Ihe dies also is tapered slightly so that rolling pressure is released gradually without marking the work. Feed rate, in terms of feed per work revolution, is proportional to...

Oo

Pj I End views of ploner-type milling machine configurations in addition to that shown in Fig. 10. Top row single-column machines with one milling spindle head (a) o' overhanging beam and two milling spindle heads (b) and cross slide, support stand, and one milling spindle head (c). Bottom row double-column machines with cross beam and two milling heads (d) cross beam, cross slide, and two milling spindle heods (e) cross beam, cross slide, ond four milling spindle heads (f) required one is...

50

(a) Based on 1 vwluc of ItM) for the mo.si uhriiMtin-rcNisfunC rn ilcn.i (a) Based on 1 vwluc of ItM) for the mo.si uhriiMtin-rcNisfunC rn ilcn.i pj a Free graphite in a tungsten carbide alloy. P Microstructures ol straight WC-Co alloys, (a) 97WC-3Co alloy, medium grain size. (b) 94WC-6Co alloy. r,5 ' Black areas contain graphite and are on medium grain, (c) 94WC-6Co alloy, coarse grain, (d) 85WC-l5Co alloy, coarse groin. All etched with example ol C-type porosity. Polished 86WC-Murakomi's...

Ii

Fig. 4 Straight-flute chucking reamers applicability arc discussed. Many of these sections also cite examples of production applications for specific types of reamers. Applications of Straight-Flute Chucking Reamers Straight-flute chucking reamers arc general-purpose solid reamers designed for use in various machines, such as drill presses, turret lathes, and automatic bar or chucking machines. They are available with taper or straight shanks (Fig. 4) and therefore can be held in collets or...

Penetration Rate and Load Requirements

The total die penetration per revolution of the blank varies with different machines, the kind of work, and (he type and hardness of the metal being rolled. Low penetration rates are necessary for hard metals, hollow workpieces. and workpieces of nt nrigid cross section. Higher penetration rates are used for rolling metals lhat work harden at an excessive rale. The rate of die penetration is normally limited by the rigidity of the workpiece and the machine and by the hardness of the metal being...

005

Feed per revolution or per tooth, mm Fig. 8 Theoretical surface roughness for turning or face milling tools with round cutting edges. Source Ref 5 wheel grade, wheel speed, downfeed or infeed. wheel dressing, and grinding fluid. As grinding parameters become more aggressive (that is, harder wheels, higher wheel speeds, increased infeed, and so on), the grinding process becomes more abusive and therefore more likely to produce surface damage. Gentle, or low-stress, grinding conditions for a...

Cemented Carbide Properties

Evaluation of the physical and mechanical properties of tool materials is an impor tant prerequisite to the selection of grades for a given metal cutting application and for tool material development. A number of industry, national, and ISO standards have been developed for determining the selected properties of cemented carbides (Tabic 5). Hardness determines the resistance of a material to abrasion and wear. Ii is affected not only by composition but also by the level of porosity and...

Drilling Steel Having 48 to 55 HRC Hardness

Successful drilling of steel that has been heal treated to a hardness of 48 to 55 HRC depends mainly on the design of the drill, the rigidity of Ihe machine setup, and the choice of tool material. As a rule, improvements in drill design and in machine and workpiece rigidity are of more direct benefit lo drilling performance lhan is a change in tool material. A number of oiher conditions may also affect drill performance, and in certain cases, they may become critical. Among these conditions are...

Functions off Cutting and Grinding Fluids

Depending on the machining operation being performed, a cutting or grinding fluid has one or more of the following functions Cooling the tool, workpiece, and chip Lubricating (reducing friction and minimizing erosion on lhe tool) Controlling built-up edge on the tool Protecting the workpiece tooling and machine from corrosion The relaiive importance of each of these functions depends on the work material, the cutting or grinding tool, the machining conditions. and the finish required on the...

Tool Replacement

Tools arc replaced to minimize the probable consequences of a failure event. The tool wear environment is so complex that even with the utmost care it is possible thai the tool may fail in service. A very conservative strategy may replace ihe tool frequently to reduce the probability of an in-process failure, but, as a consequence, interrupt the process so frequently that productivity decreases and lool cosis increase. To establish the strategy objectively, a clear understanding of the failure...

Surface Speed

Permissible surface speeds for thread rolling are governed by the mechanical power limitations of the threading equipment and. when the workpiecc is rotated, by the speed (rcv min) of the workpiece or of the holding equipment used with end-feeding heads. Table 7 compares die surface speeds in modern thread rolling equipment with the surface speeds of thread cutting tools. Table 8 shows the approximate thread rolling time for different spindle speeds used with tan-gcntial-infccd double-roll...

Thread Milling Machines

Conventional (up-thread) milling can be done on all types of thread millers, but some models are also designed for climb (down-thread) milling. In climb milling, the relative rotation of the work and the cutler is similar to that of a pair of mating gears. Figure 1 illustrates conventional milling with a single-form cutter. Thread milling machines can be either planetary or conventional machines. In planetary machines the workpiece does not rotate, while in conventional machines the workpiece...

Surface Finish and Surface Integrity

Kahles, and William P. Koster, Metcut Research Associates Inc. A PARI SURFACE has (wo important aspects that must be defined and controlled. The first concerns the geometric irregularities of the surfacc. and the second concerns (he metallurgical alterations of the surface and the surface layer. This second aspect has been termed surface integrity. Both surfacc finish and surface integrity must be defined, measured, and maintained within specified limits in the processing...

K20 M20

M41-M47)orlS9. SID. SII.SI2). Source Mctcut Research Associates Int high-speed steel (TU. M. . . M41-M47)orlS9. SID. SII.SI2). Source Mctcut Research Associates Int al accuracy required, method of advancing the cutter (manual or automatic), work-metal hardness, and rate of cutter feed. Excessive unsupported length can sometimes be tolerated when soft metals are being milled with light feeds. For most applications, however, an unsupported length greater than about...

Image For Stationary Machine Civil Engineers

Fixed Bed Type Milling Machine

These relationships are not standardized, and a particular machine may vary considerably from these values. A typical No. 3 machinc has maximum table, saddle, and knee movement of 812. 305. and 508 mm (32. 12. and 20 in.), respectively. A No. 6 machine has a table travel of 1525 mm (60 in.), cross travel of 457 mm (18 in.), and a vertical travel of 508 mm (20 in.). Advantages and Limitations. The method of operating knee-and-column machines r * at Principal components of the ram-type knee-rig...

Milling Cutters

Milling cutters vary widely in type and size and are broadly classified as peripheral mills, face mills, end mills, and special mills. Cutters can be of the solid, lipped, or inserted tooth types and have the same-materials as single-point tools. Large cutters commonly have teeth of expensive material that are inserted and locked in place in a soft steel or cast iron body. Peripheral mills (Fig. 16) are so named because cutting is mainly done by leelh on the periphery to produce the finished...

Surface Finish or Surface Texture

Surface finish as described in Ref I is concerned with only the geomeiric irregularities of surfaces of solid materials and the characteristics of instruments for measuring roughness. Surface lexturc is defined in terms of roughness, waviness, lay. and flaws (Fig. I) Surface roughness consists of fine irregularities in the surface texture, usually including those resulting from the inherent action of the production process, such as feed marks produced during machining Waviness is a more widely...

149 189

Fin OA l nProveme ,, in surface finish and machin-9* ing efficiency that resulted from change in composition of carbide tools used for turning, facing, and chamfering duster-gear blanks. Dimensions in figure given in inches Fin OA l nProveme ,, in surface finish and machin-9* ing efficiency that resulted from change in composition of carbide tools used for turning, facing, and chamfering duster-gear blanks. Dimensions in figure given in inches 50 greater than nominal (see Table 6), and five...

Climb Milling Versus Conventional Milling

The relationships between cutter rotation and feed direction in climb milling and in conventional milling are shown in Fig. 28. In climb milling, as implied by the name, the milling cutter attempts to climb Ihe work-piece. Climb milling is also called down milling. Conventional milling is often referred to as up milling. In climb milling, chips arc cul to maximum thickness at the initial engagement of cutter teeth with the work and then decrease to zero thickness at the end of engagement. In...

Causes and Prevention of Broach Breakage

Broaches that are properly designed and well made seldom break in normal use. Broach breakage is usually the result of poor processing practices (such as failure to maintain tooth sharpness, overloading, or improper sharpening), careless handling of the broach, or improper preparation or excessive hardness of the workpiece. Poor Processing Practices. More force is required for pulling a dull broach through ihe workpiece than is required for a sharp broach. If a broach is sufficiently dull,...

Orthogonal Machining Fundamentals

Orthogonal machining setups are used to model oblique machining processes. Processes such as turning, drilling, milling, and shaping are all three-force, or oblique, cutting methods. However, the orthogonal model shown in Fig. 4 is an excellent illustration of the behavior of oblique processes without the complications of the third dimension. Chip Ratio. As described earlier in this article, orthogonal machining can be accomplished by machining a plate or can be approximated by cutting the end...

Small Hole Drilling Microdrilling

The drilling of small holes (diameters of 0.025 to 1.2 mm. or 0.001 to Vx in.I requires machines, drills, techniques, and operator skills different from those used in conventional drilling. Machines used for drilling small holes are usually bench-mounted and resemble a jeweler's drill press (Fig. 2). Alignment of spindle and tabic at any position should be within 0.013 mm in 152 mm (0.0005 in. in f> in.), or at a radius equal to half the length of the table. Runout of the spindle should nol...

Truing Grinding Wheels

I hread grinding wheels are trued to maintain the required thread form and an efficient grinding surface. Thread grinders arc usually equipped with precision Iruing devices that function automatically. One type automatically dresses ihe wheel and compensates for the slight amount removed in dressing, thus automatically maintaining size control of the work. Diamond Dressing. In most cases, suitably mounted diamond points are the cutting tools used to impart the desired form to the grinding wheel...

Types of Drilling Machines

Line Diagram Gang Drilling Machine

The basic work and tool motions that are required for drilling relative rotation between the workpiece and the tool, with relative longitudinal feeding also occur in a number of other machining operations. Consequently, drilling can be done on a variety of machine tools, such as lathes, milling machines, and boring machines. This section will focus on machines that are designed, constructed, and used primarily for drilling. Drilling machines, called drill presses, consist of a base, a column...

The Wear Environment

Cutting tool wear occurs along ihe cutting edge and on adjacent surfaces. Figure I shows a view of Ihe culling process in which the rake and clearance surfaces intersect lo define the cutting edge. Figure 2 in the article Mechanics of Chip Formation in this Volume shows a similar view bill adds the stress and strain states thai are present in the material and chip Fig. 4 from ihe same article also shows the machining forces and velocities lhat produce this state of stress and strain. These are...

Milling Machines

Milling Machine Engineering Drawing

Most milling is done in machines designed primarily for milling, but milling has been done in almost every type of machine that can rigidly hold and rotate a cutter while allowing a workpiece to be fed into the cutler, or vice versa. Figure 1 illustrates the wide range of cutler configurations available for use in milling operations. For example, milling can be done in single-spindie or multiple-spindle bar and chucking machines in sequence with other machining operations (see ihe section...

Surface Finishes In Civil Engineering

Horizontal Broaching Machine Figure

Fig. 7 Classification of broaching machines than pushed through the workpiece. because a broach tool is stronger in tension than in compression. This in turn helps determine the type of machine for the job. A short push broach is often handled in a press instead of an expensive ram-type broaching machine. Presses can of course be converted to pull short broaches by the addition of a pull-down adaptor, which converts push strokes to pull strokes. Lubrication, workpiece size, chip-handling...

35

1 'I Top. design of carbide-lip drills used to drill HI I steel sheet at 54 HRC. Bottom comparison ol tool life for the three grades of carbide tested on drills of the above design for performance in drilling 6.35 mm (0.250 in.) diam holes through two 2.11 mm (0.083 in.) thick sheets of this steel. Dimensions In ligure given in millimeters Fig. 34 Two types of indexable carbide insert drills, (a) Two-insert drill, (b) Four-insert drill available provide savings from not having to replace the...

Planetary Thread Rolling

Planetary thread rolling machines have one ccntral rotating die on a fixed axis and one or more stationary concave segment dies located near the outside of the rotary die, as shown in Fig. 15. One or several blanks may be rolled on a segment die al one time, depending on the gearing of the stalling mechanism. The starting end of the segment is adjusted so that the blank contacts both dies. As the rotary die revolves, the blank is rolled between the dies until u traverses the full arc of the...

Fundamentals of Broaching

Each tooth on a broach is essentially a single-edge cutting tool, arranged much like the teeih on a saw except for ihe step (rise per tooth), which determines the depth cut by each tooth. The depth of cut can vary from approximately 0.15 mm ((1.006 in.) for roughing teeth in machining free-cultmg steel to a minimum of 0.025 mm (O.(K)I in.) for finishing teeth. Brooch Tooth Terminology. Usually, a broach is a tapered bar into which teeth have been cut so as lo produce a desired contour in a...

Classification of Cemented Carbides

There is no universally accepted system for classifying cemented carbides. The systems mosl often employed by producers and users are discussed below. Each system has inherent strengths and weaknesses in describing specific materials, and for this reason close cooperation between user and Fi a 7 Representative microstruclures of steel-cutting grades of tungsten carbide (a) 85WC-9(Ta.Ti,Nb)C-6Co alloy, medium grain size, (b) 78WC-15(Ta,Ti.Nb)C-7Co ' * alloy, medium grain, (c)...

References

Surface Studies of Diamond. Ind. Diamond Rev No. 1965. p 486-489 2. A. Sawaoka. Boron Nitride Structural Changes by Shock Compression and Preparation of Superhard Compacts by Very High Pressure Sintering, Ceram. Bull Vol 62 (No. 12). 1983. p 1379 3. R. Berman and F. Simon, 7 Elektro-chern Vol 49 (No. 333), 1955 4. R.J. Wedlake, Technology of Diamond Growth, in The Properties of Diamond. J. Field. Ed Academic Press, 1979 5. P.A. Bex and G.R. Shafto, The Influence of Temperature and...

Flat Die Rolling

Flat traversing dies are the type most commonly used for rolling threads in commercial fasteners and similar parls. One technique involves the use of two flat, rectangular dies one is stationary, and the other traverses in a plane parallel to the stationary die and separated from it by a distance equal to the minor diameter of the thread to be rolled. In another technique, both dies traverse the workpicce. Figure X shows ihe most common arrangement of dies and work-piece. As the biank is forced...

0175

1,1) Euch sleel listed is a frequently used grade in a group ot similar steels listing of the steels itt the various groups is provided in Table 2 in (he article Honng in this Volume Source Mclcut Research Associates 1,1) Euch sleel listed is a frequently used grade in a group ot similar steels listing of the steels itt the various groups is provided in Table 2 in (he article Honng in this Volume Source Mclcut Research Associates 17 to 24 m min (55 to 80 sl'm) for steel at 1 ) HB. regardless of...

Grooves Slots and Keyways

Vertical machines are usually used in preference to horizontal shapers for cutting external or internal grooves. This is particularly true when two or more grooves must be kept in a specific relationship to each other, because indexing for cutting in a vertical plane is usually simpler. External grooves can be machined on shapers to about the same degree of dimensional accuracy as in milling. Holding close dimensions on external grooves cut on a shaper depends largely on the accuracy of Ihe...

Types of Broaches

There are three general categories of broaches solid, shell, and insert-type. Within these categories, broaches can be further classified by the type of cut internal or external hey are designed o make and by the method by which they are actuated push or pull . Of the various types of broaches, the solid pull broach Fig. 13 is probably the most commonly used. Solid broaches are one-piece broaches produced from bar stock Fig. I and 13 . They can be provided with greater dimensional accuracy and...

Fundamental Mechanism off Metal Deformation

Metal Cutting Feed

Before the mechanics of machining are presented, a brief discussion of the fundamental nature of the deformation processes is helpful in understanding the assumptions that accompany the mechanics. The machining geometry can be simplified from the three-dimensional oblique geometry, which typifies most industrial processes, to a two-dimensional orthogonal geometry. Figure I compares the oblique and the orthogonal cutting geometries. Orthogonal machining can be obtained in...

Tool Geometry Angle

Photo Tool Geometry

Where p is the density of the work material and t is the feed or uncut chip thickness. Chip thickness is usually greater than the depth of cut, . and is constrained by the rake face of the cutting tool. Shear Angle. There are numerous other ways to measure or compute the shear angle, both during dynamically the cutting process and after statically it has been halted. The shear angle can be measured statically by instantaneously interrupting the cut through the use of quick-stop devices. These...