Lathe Shop Lab Manual
lathe w/s for mech guys...
AMRITA VISHWA VIDYAPEETHAM
AMRITA SCHOOL OF ENGINEERING, BANGALORE
Lathe Shop and Special Machines Lab
DEPARTMENT OF MECHANICAL ENGINEERING
GENERAL SHOP SAFETY All tools are dangerous if used improperly or carelessly. Working safely is the first thing the user or operator should learn because the safe way is the correct way. A person learning to operate machine tools must first learn the safety regulations and precautions for each tool or machine. Most accidents are caused by not following prescribed procedures. Develop safe work habits rather than suffer the consequences of an accident. Most of the safety practices mentioned in this section are general in nature. Safety precautions for specific tools and machines are described in detail in the chapters along with the description of the equipment. Study these carefully and be on the alert to apply them. EYE PROTECTION Using eye protection in the machine shop is the most important safety rule of all. Metal chips and shavings can fly at great speeds and distances and cause serious eye injury. Safety glasses must be worn when working with hand-cutting tools, since most hand-cutting tools are made of hardened steel and can break or shatter when used improperly. Safety goggles should be worn over prescription glasses. HAZARDOUS NOISE PROTECTION Noise hazards are very common in the machine shop. High intensity noise can cause permanent loss of hearing. Although noise hazards cannot always be eliminated, hearing loss is avoidable with ear muffs, ear plugs, or both. FOOT PROTECTION The floor in a machine shop is often covered with razor-sharp metal chips, and heavy stock may be dropped on the feet. Therefore, safety shoes or a solid leather shoe must be worn at all times. ELECTRICAL SAFETY Exposure to electrical hazard will be minimal unless the operator becomes involved with machine repair. The machine operator is mostly concerned with the on and off switch on the machine tool. However, if adjustments or repairs must be made, the power source should be disconnected. If the machine tool is wired permanently, the circuit breaker should be switched off and tagged with an appropriate warning statement. Most often the power source will not be disconnected for routine adjustment such as changing machine speeds. However, if a speed change involves a belt change, make sure that no other person is likely to turn on the machine while the operator’s hands are in contact with belts and pulleys. SAFETY RULES FOR MACHINE TOOLS Since different cutting tools and machining procedures are used on various machine tools, the safety precautions for each may vary. The following are general safety rules for any machine tool: Gears, pulleys, belts, couplings, ends of shafts having keyways, and other revolving or reciprocating parts should be guarded to a height of 6 feet above the floor. The guards should be removed only for repairing or adjusting the machine and must be replaced before operating it. Safety setscrews should be used in collars and on all revolving or reciprocating members of the machine tool or its equipment. Do not operate any machine tool without proper lighting. Never attempt to operate any machine tool until you fully understand how it works and know how to stop it quickly.
Never wear loose or torn clothing and secure long hair, since these items can become caught in revolving machine parts. Ties should be removed and shirt sleeves should be rolled up above the elbow. Gloves should never be worn when operating machinery except when absolutely necessary. Always stop the machine before cleaning it or taking measurements of the workpiece. Do not lubricate a machine while it is in motion. Injury to the operator and damage to the machine may result from this practice. Never remove metal chips, turnings, or shavings with your hands; they may cause a serious cut. If the shavings are long, stop the machine and break them with pliers or a bent rod, and then brush chips off the machine. Remove cast-iron chips, which break into small pieces, with a brush. Never wipe away chips when the machine is operating. Always wear safety glasses or goggles while operating machine tools. Also, wear respiratory protection if operation creates hazardous dust. All persons in the area where power tools are being operated should also wear safety eye protection and respirators as needed. Know where fire extinguishers are located in the shop area and how to use them. Never wear jewelry while working around machine tools. Rings, watches, or bracelets maybe caught in a revolving part which could result in the hand being pulled into the machine. Avoid horseplay. Tools are very sharp and machines are made of hard steel. An accidental slip or fall may cause a serious injury. Never use compressed air without a safety nozzle to clean machines or clothing. It will blow sharp, dangerous metal chips a long distance. Keep the floor around machines free of tools, stock, oil, grease, and metal chips. Tripping over metal on the floor, especially round bars, can cause dangerous falls. Wipe up all oil, grease, and cutting fluid spills on the floor as soon as possible to prevent a fall. Metal chips are very sharp and can easily become embedded in the soles of shoes, making them very slippery, especially when walking on a concrete floor. Never place tools or other materials on the machine table. Cluttering up a machine with tools or materials creates unsafe working conditions. Always use a rag when handling sharp cutters such as milling cutters and end mills. Do not expose power tools to rain or use in damp or wet Remove adjusting keys and wrenches. Form a habit of locations. Checking to see that keys and wrenches are removed from tools before turning them on. Always secure the workpiece. Use clamps or a vise. It is safer than using your hands, and it frees both hands to Do not operate any machine tool while under the operate the tool influence of drugs, alcohol, or any medication that could cause drowsiness. Do not abuse electrical cords. Never carry a tool by its cord or yank it to disconnect it from a receptacle. Keep Electrical cords away from heat, oil, and sharp edges. Have damaged or worn power cords and strain relievers repaired or replaced immediately.
ENGINE LATHE A lathe is a machine tool which rotates the workpiece on its axis to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation. Lathes are used in woodturning, metalworking, metal spinning, and glass working. Lathes can be used to shape pottery, the best-known design being the potter's wheel. Most suitably equipped metalworking lathes can also be used to produce most solids of revolution, plane surfaces and screw threads or helices. Ornamental lathes can produce three-dimensional solids of incredible complexity. The material can be held in place by either one or two centers, at least one of which can be moved horizontally to accommodate varying material lengths. Other workholding methods include clamping the work about the axis of rotation using a chuck or collet, or to a faceplate, using clamps or dogs. Examples of objects that can be sticks, table legs, bowls, baseballbats, instruments), crankshafts and camshafts.
a lathe include candlestick holders, cue instruments (especially woodwind
The Bed : The lathe bed is a mounting and aligning surface for the other machine components. Viewed from the operating position in front of the machine, the headstock is mounted on the left end of the bed and the tailstock on the right. The bed must be bolted to a base to provide a rigid and stable platform. The
bed ways are a precision surface (or surfaces) on which the carriage slides left and right during machining operations. The ways are machined straight and flat and are either bolted to the top of the bed or are an integrally machined part of the bed. Headstock: The headstock holds the spindle and drive mechanism for turning the work piece. The spindle is a precision shaft and bearing arrangement rotated directly by a motor or through a motor-driven belt. Gears or sliding pulleys mounted at the rear of the headstock allow spindle speed adjustment. A work piece is held in the spindle for turning or drilling by a jawed chuck or a spring collet system. Large, unusual shaped, or otherwise difficult to hold pieces, can be attached to the spindle with a face plate, drive dogs and special clamps. Tailstock: The tailstock supports long work that would otherwise sag or flex too much to allow for accurate machining. Without a tailstock, long pieces cannot be turned straight and will invariably have a taper. Some tailstocks can be intentionally misaligned to accurately cut a taper if needed. The tailstock has a centering device pressed into a shallow, specially drilled hole in the end of the work piece. The center can be either "live" or "dead." Live centers have a bearing, allowing the center to rotate along with the work piece. Dead centers do not rotate and must be lubricated to prevent overheating due to friction with the work piece. Instead of a center, a drill chuck can be mounted in the tailstock. Carriage: The carriage provides mounting and motion control components for tooling. The carriage moves left and right, either through manual operation of a hand wheel, or it can be driven by a lead screw. At the base of a carriage is a saddle that mates and aligns with the bed ways. The cross-slide, compound rest and tool holder are mounted to the top of the carriage. Some carriages are equipped with a rotating turret to allow a variety of tools to be used in succession for multi-step operations. Cross Slide: The cross-slide is mounted to the top of the carriage to provide movement perpendicular to the length of the bed for facing cuts. An additional motion assembly, the compound rest, with an adjustable angle, is often added to the top of the cross slide for angular cuts. The cutting tools that do the actual metal removal during turning are mounted in an adjustable tool holder clamped to the compound rest. Lead Screw: The lead screw provides automatic feed and makes thread cutting possible. It is a precision-threaded shaft, driven by gears as the headstock turns. It passes through the front of the carriage apron and is supported at the tailstock end by a bearing bracket. Controls in the apron engage a lead nut to drive the carriage as the lead screw turns.
SPECIFICATIONS of Lathe Machine 1. Swing over machine bed 2. Swing over cross slide 3. Distance between centers 4. Turning Length 5. Width of bed 6. Work Spindle diameter in front bearing 7. Spindle Bore 8. Taper bore according to DIN 228(shortened) 9. Normal Chuck diameter 10. Max. Diameter of face plate and clamping disk
11. Tool Slide & Guide Length of carriage 12 Graduation of Longitudinal scale on apron box hand wheel 13 Cross-slide travel 14 Graduation of scale at cross slide spindle 15 Width of cross-slide 16 Compound slide travel 17 Graduation of scale on compound slide spindle 18 Width of top slide 19 Tailstock with hand wheel 20 Diameter of center sleeve
21 Taper sockets 22 Scale graduations on center sleeve 23 Scale ring at tail stock spindle, scale graduation 24. Cross Travel 25. Number of speed ranges 26. Thread pitches with standard change gear set 27. Lead Screw pitch
28. Coolant tank with complete pump capacity 29. Floor Space required 30. Length x width x Height of machine 31. Work spindle above floor 32. Sound pressure level according to DIN 45635-16 33. Sound power level according to DIN 45635-16
Types of Lathe Engine Lathe The most common form of lathe, motor driven and comes in large variety of sizes and shapes. Bench Lathe A bench top model usually of low power used to make precision machine small work pieces. Tracer Lathe A lathe that has the ability to follow a template to copy a shape or contour. Automatic Lathe A lathe in which the work piece is automatically fed and removed without use of an operator. Cutting operations are automatically controlled by a sequencer of some form Turret Lathe lathe which have multiple tools mounted on turret either attached to the tailstock or the cross-slide, which allows for quick changes in tooling and cutting operations. Computer Controlled Lathe A highly automated lathe, where both cutting, loading, tool changing, and part unloading are automatically controlled by computer coding.
Conventional Types of Lathes
Numerical Control Lathe and Turret Lathe Operations Turning: produce straight, conical, curved, or grooved workpieces Facing: to produce a flat surface at the end of the part or for making face grooves. Boring: to enlarge a hole or cylindrical cavity made by a previous process or to produce circular internal grooves. Drilling: to produce a hole by fixing a drill in the tailstock Threading: to produce external or internal threads Knurling: to produce a regularly shaped roughness on cylindrical surfaces
Work Holding Devices Three jaw chuck: For holding cylindrical stock centered and For facing/center drilling the end of your aluminum stock Four-Jaw Chuck: - This is independent chuck generally has four jaws , which are adjusted individually on the chuck face by means of adjusting screws
Fig.a. Three Jaw Chuck Fig.b. Four Jaw Chuck Collet Chuck: Collet chuck is used to hold small workpieces Magnetic Chuck: Thin jobs can be held by means of magnetic chucks.
Fig.c. Collet Chuck
Fig.d. Magnetic Chuck
GENERAL PURPOSE CUTTING TOOLS The lathe cutting tool or tool bit must be made of the correct material and ground to the correct angles to machine a workpiece efficiently. The most common tool bit is the general all-purpose bit made of high-speed steel. These tool bits are generally inexpensive, easy to grind on a bench or pedestal grinder, take lots of abuse and wear, and are strong enough for all-around repair and fabrication. High-speed steel tool bits can handle the high heat that is generated
during cutting and are not changed after cooling. These tool bits are used for turning, facing, boring and other lathe operations. Tool bits made from special materials such as Single point tool bits can be one end of a high-speed steel tool bit or one edge of a carbide or ceramic cutting tool or insert. Basically, a single point cutter bit is a tool that has only one cutting action proceeding at a time. A machinist or machine operator should know the various terms applied to the single point tool bit to properly identify and grind different tool bits SINGLE POINT TOOL BITS The shank is the main body of the tool bit. The nose is the part of the tool bit which is shaped to a carbides, ceramics, diamonds, cast alloys are able to machine workplaces at very high speeds but are brittle and expensive point and forms the corner between the side cutting edge For normal lathe work, high-speed steel tool bits are used. The nose radius is the rounded end of the tool bit. The face is the top surface of the tool bit upon which the chips slide as they separate from the work piece. The side or flank of the tool bit is the surface just below and adjacent to the cutting edge. The cutting edge is the part of the tool bit that actually cuts into the workpiece, located behind the nose and adjacent to the side and face. The base is the bottom surface of the tool bit, which usually is ground flat during tool bit manufacturing. The end of the tool bit is the near-vertical surface which, with the side of the bit, forms the profile of the bit. The end is the trailing surface of the tool bit when cutting. The heel is the portion of the tool bit base immediately below and supporting the face.
MACHINING Machining is a manufacturing process in which a cutting tool is used to remove excess material from a workpiece. The material that remains is the desired part geometry. The cutting tool deforms the workpiece in shear and creates scrap called “chips.” As chips fall off the workpiece a new surface is exposed. Almost all solid metals, plastics, and composites can be machined by conventional machining. Machining can create any regular geometry, i.e., planes, round holes, and cylinders. Machining can produce dimensions to tolerances of less than 0.001” (0.025mm) Surface finishes of better than 16μin (0.4 μm) can be produced by machining processes. A cutting tool has one cutting edge (facing tool or turning tool) or more than one cutting edges (drill, end mill). The cutting edge separates the chip from the workpiece.
The rake face of a tool guides the chip from the surface of the workpiece and is oriented at an angle α. The rake angle α is measured relative to a plane perpendicular to the work surface. The flank of a tool provides clearance between the cutting tool and the newly exposed surface to protect the surface from
abrasion. The flank is oriented at an angle called the relief angle. The picture below illustrates the make-up of a cutting tool.
Discontinuous chips: This type of chip is usually formed when cutting hard, brittle materials, partly because these materials cannot withstand high shear forces and therefore the chips formed shear cleanly away. However, the chips formed may be firmly or loosely attached to each other or may leave the cutting area in a fine shower – as often encountered when cutting hard Brass. When discontinuous chips are formed there is a greater possibility of tool chatter; unless the tool, tool-holder and workpiece are held very rigidly; due to pressure at the tool tip increasing during chip formation and then releasing suddenly as the chip shears. Continuous chips: This type of chip is usually formed when cutting soft or ductile materials such as Aluminium or Copper. There is less likelihood of chatter and surface finish is usually better than when discontinuous chips are formed. A disadvantage of continuous chips is the fact that they can become very long and become entangled with the machine or pose a safety hazard. This problem can be overcome by the use of chip-breakers; a device clamped to the top of the tool that encourages the chip to curl more tightly, hitting the workpiece and breaking off.
Built Up Edge: Figure shows a tool with a Built up Edge (B.U.E.). A B.U.E. is formed when particles of the workpiece material weld to the rake face of the tool during cutting. Large B.U.E.s can be very detrimental to surface finish and integrity, they effectively change the geometry of the cutting edge and
consequently shear plane angle, this can lead to residual stresses in the material below the depth of cut. As a large B.U.E. dislodges it can deposit work hardened particles, to become embedded in the finished surface. A thin, stable B.U.E. is generally considered desirable as this can tend to reduce frictional wear on the rake face of the tool. TOOL WEAR: Wedge shape cutting tools normally wear in two ways. Figure shows the typical wear pattern of a wedge shape cutting tool. Crater wear occurs on the rake face of the tool just behind the cutting edge and is caused by the rubbing of the chip across the surface. Flank wear occurs on the clearance angle of the tool causing rubbing and degradation of the surface finish. Cutting tools are deemed to have failed and require regrinding or replacing when flank wear exceeds 0.25mm or when cratering appears, this allows regrinding with minimal removal of tool material. It can be seen from Figure that when cratering appears the cutting edge becomes thinned and less able to dissipate the heat generated during cutting; leading to unpredictable and possibly catastrophic, failure.
Built up edge
General Recommendations for Tool Angles in Turning
MILLING MACHINE A milling machine is a power driven machine that cuts by means of a multitooth rotating cutter. The mill is constructed in such a manner that the fixed workpiece is fed into the rotating cutter. Varieties of cutters and holding devices allow a wide range of cutting possibilities. The mills in the Student Shop are vertical milling machines, commonly called “Bridgeport” style mills. These versatile mills are capable of performing many operations, including some that are similar to those performed on the drill press like drilling, reaming, countersinking, and counterboring. Other operations performed on the mill include but are not limited to: side and face milling, flycutting, and precision boring. Mills are classified on the basis of the position of their spindle. The spindle operates in either a vertical or horizontal position. The amount of horsepower the mill is able to supply to the cutter is also often important. METHODS OF MILLING Up Milling: Up milling is also referred to as conventional milling. The direction of the cutter rotation opposes the feed motion. For example, if the cutter rotates clockwise, the workpiece is fed to the right in up milling.
Down Milling: Down milling is also referred to as climb milling. The direction of cutter rotation is same as the feed motion. For example, if the cutter rotates counterclockwise, the workpiece is fed to the right in down milling.
The chip formation in down milling is opposite to the chip formation in up milling. The figure for down milling shows that the cutter tooth is almost parallel to the top surface of the workpiece. The cutter tooth begins to mill the full chip thickness. Then the chip thickness gradually decreases. Milling Cutters A milling cutter is a cutting tool that is used on a milling machine. Milling cutters are available in many standard and special types, forms, diameters, and widths. The teeth maybe straight (parallel to the axis of rotation) or at a helix angle. The helix angle helps a slow engagement of the tool distributing the forces .The cutter may be right-hand (to turn clockwise) or left-hand (to turn counterclockwise).The figure shows a typical end milling cutter.
Types of milling cutters : a) Helical Milling Cutters b) Metal Slitting Saw Milling Cutter c) Side Milling Cutters d) End Milling Cutters e) T-Slot Milling Cutter f) Woodruff Keyslot Milling Cutters g) Angle Milling Cutters h) Gear Hob i) Concave and Convex Milling Cutters j) Corner Rounding Milling Cutter k) Special Shaped-Formed Milling Cutter
Milling Operations Side milling - machining a plane surface perpendicular to the milling machine arbor with an arbor mounted tool. This tool is called a side mill. Straddle milling - milling two parallel surfaces using two cutters spaced apart on an arbor. Gang milling - milling multiple surface simultaneously using multiple cutters mounted on an arbor. Thread milling - milling treads using the capability of a three axis contouring CNC machine.
Types of Milling Machines Vetical: Vertical milling machines have a cutting blade that is vertically positioned over a table. The blade points directly down into the surface of the metal that it is going to cut. This cutting blade moves up and down while the table moves below it to position the metal for the cut. This allows different sections of the object to be cut, drilled or carved away by the cutting tool. This is the most common milling machine. Horizontal: The horizontal milling machine has a cutting blade that points straight out at a 90 degree angle horizontally from the machine. It moves up and down while the table that holds the object that is being cut moves from side to side. This allows the object to be cut in different positions.
INDEXING Indexing is the process of evenly dividing the circumference of a circular workpiece into equally spaced divisions, such as in cutting gear teeth, cutting splines, milling grooves in reamers and taps, and spacing holes on a circle. The index head of the indexing fixture is used for this purpose. Index Head: The index head of the indexing fixture contains an indexing mechanism which is used to control the rotation of the index head spindle to space or divide a workpiece accurately. A simple indexing mechanism consists of a 40-tooth worm wheel fastened to the index head spindle, a single-cut worm, a crank for turning the wormshaft, and an index plate and sector. Since there are 40 teeth in the worm wheel, one turn of the index crank causes the worm, and consequently, the index head spindle to make 1/40 of a turn; so 40 turns of the index crank revolve the spindle one full turn.
Fig: Indexing head
Index Plate: The indexing plate is a round plate with a series of six or more circles of equally spaced holes; the index pin on the crank can be inserted in any hole in any circle. With the interchangeable plates regularly furnished with most index heads, the spacing necessary for most gears, boltheads, milling cutters, splines, and so forth can be obtained. The following sets of plates are standard equipment.
Index plate and sector Brown and Sharpe type consists of 3 plates of 6 circles each drilled as follows: Plate I -15, 16, 17, 18, 19, 20 holes Plate 2-21, 23, 27, 29, 31, 33 holes Plate 3-37, 39, 41, 43, 47, 49 holes Cincinnati type consists of one plate drilled on both sides with circles divided as follows: First side -24, 25, 28, 30, 34, 37, 38, 39,41,42,43 holes Second side -46, 47, 49, 51, 53, 54, 57, 58, 59, 62, 66 holes Plain Indexing The following principles apply to basic indexing of workpieces: Suppose it is desired to mill a project with eight equally spaced teeth. Since 40 turns of the index crank will turn the spindle one full turn, l/8th of 40 or 5 turns of the crank after each cut will space the gear for 8 teeth, If it is desired to pace equally for 10 teeth, 1/10 of 40 or 4 turns would produce the correct spacing. The same principle applies whether or not the divisions required divide equally into 40, For example, if it is desired to index for 6 divisions, 6 divided into 40 equals 6 2/3 turns; similarly, to index for 14 spaces, 14 divided into 40 equals 2 6/7 turns. These examples may be multiplied indefinitely and from them the following rule is derived: to determine the number of turns of the index crank needed to obtain one division of any number of equal divisions on the workpiece, divide 40 by the number of equal divisions desired (provided the worm wheel has 40 teeth, which is standard practice).
Direct Indexing The construction of some index heads permits the worm to be disengaged from the worm wheel, making possible a quicker method of indexing called direct indexing. The index head is provided with a knob which, when turned through part of a revolution, operates an eccentric and disengages the worm. Direct indexing is accomplished by an additional index plate fastened to the index head spindle. A stationary plunger in the index head fits the holes in this index plate. By moving this plate by hand to index directly, the spindle and the workpiece rotate an equal distance. Direct index plates usually have 24 holes and offer a quick means of milling squares, hexagons, taps, and so forth. Any number of divisions which is a factor of 24 can be indexed quickly and conveniently by the direct indexing method. Indexing Operations The following examples show how the index plate is used to obtain any desired part of a whole spindle turn by plain indexing, Milling a hexagon. Using the rule previously given, divide 40 by 6 which equals 6 2/3 turns, or six full turns plus 2/3 of a turn or any circle whose number is divisible by 3. Take the denominator which is 3 into which of the available hole circles it can be evenly divided. In this case, 3 can be divided into the available 18-hole circle exactly 6 times. Use this result 6 as a multiplier to generate the proportional fraction required.
Therefore, 6 full turns of the crank plus 12 spaces on an 18- hole circle is the correct indexing for 6 divisions. Cutting a gear. To cut a gear of 52 teeth, using the rule again, divide 40 by 52. This means that less than one full turn is required for each division, 40/52 of a turn to be exact. Since a 52-hole circle is not available, 40/52 must be reduced to its lowest term which is 10/13. Take the denominator of the lowest term 13, and determine into which of the available hole circles it can be evenly divided. In this case, 13 can be divided into a 39-hole circle exactly 3 times. Use this result 3 as a multiplier to generate the proportional fraction required.
Therefore, 30 holes on a 39-hole circle is the correct indexing for 52 divisions. When counting holes, start with the first hole ahead of the index pin.
SHAPING MACHINE A shaper is a type of machine tool that uses linear relative motion between the workpiece and a singlepoint cutting tool to machine a linear toolpath. Its cut is analogous to that of a lathe, except that it is (archetypally) linear instead of helical. (Adding axes of motion can yield helical tool paths, as also done in helical planing.) A shaper is analogous to a planer, but smaller, and with the cutter riding a ram that moves above a stationary workpiece, rather than the entire workpiece moving beneath the cutter. The ram is moved back and forth typically by a crank inside the column; hydraulically actuated shapers also exist.
Uses: The most common use is to machine straight, flat surfaces, but with ingenuity and some accessories a wide range of work can be done. Other examples of its use are: Keyways in the boss of a pulley or gear can be machined without resorting to a dedicated broaching setup. b) Dovetail slides c)Internal splines d)Keyway cutting in blind holes e)Cam drums with toolpaths of the type that in CNC milling terms would require 4- or 5-axis contouring or turn-mill cylindrical interpolation f)It is even possible to obviate wire EDM work in some cases. Starting from a drilled or cored hole, a shaper with a boring-bar type tool can cut internal features that don't lend themselves to milling or boring (such as irregularly shaped holes with tight corners). Operation A shaper operates by moving a hardened cutting tool backwards and forwards across the workpiece. On the return stroke of the ram the tool is lifted clear of the workpiece, reducing the cutting action to one direction only. The workpiece mounts on a rigid, box-shaped table in front of the machine. The height of the table can be adjusted to suit this workpiece, and the table can traverse sideways underneath the reciprocating tool, which is mounted on the ram. Table motion may be controlled manually, but is usually advanced by automatic feed mechanism acting on the feedscrew. The ram slides back and forth
above the work. At the front end of the ram is a vertical tool slide that may be adjusted to either side of the vertical plane along the stroke axis. This tool-slide holds the clapper box and toolpost, from which the tool can be positioned to cut a straight, flat surface on the top of the workpiece. The tool-slide permits feeding the tool downwards to deepen a cut. This adjustability, coupled with the use of specialized cutters and toolholders, enable the operator to cut internal and external gear tooth profiles, splines, dovetails, and keyways. The ram is adjustable for stroke and, due to the geometry of the linkage, it moves faster on the return (non-cutting) stroke than on the forward, cutting stroke. This action is via a slotted link or Whitworth link.
Shaping machines Shaping machines are neither productive nor versatile. However, its limited applications include : Δ Machining flat surfaces in different planes. Figure shows how flat surfaces are produced in shaping machines by single point cutting tools in (a) horizontal, (b) vertical and (c) inclined planes. Δ Making features like slots, steps etc. which are also bounded by flat surfaces. Figure visualises the methods of machining (a) slot, (b) pocket (c) T-slot and (d) Vee-block in shaping machine by single point tools. Δ Forming grooves bounded by short width curved surfaces by using single point but form tools. Figure typically shows how (a) oil grooves and (b) straight tooth of spur gears can be made in shaping machine Δ Some other machining applications of shaping machines are cutting external keyway and splines, smooth slitting or parting, cutting teeth of rack for repair etc. using simple or form type single point cutting tools.
Figure: Machining of flat surfaces in shaping machines Some unusual work can also be done, if needed, by developing and using special attachments.
Figure: Machining (a) slot, (b) pocket (c) T-slot and (d) Vee block in shaping machine
Figure: Making grooves and gear teeth cutting in shaping machine by form tools. However, due to very low productivity, less versatility and poor process capability, shaping machines are not employed for lot and even batch production. Such low cost primitive machine tools may be reasonably used only for little or few machining work on one or few pieces required for repair and maintenance work in small machine shops.
1. Kalpakjian S., Introduction to Manufacuring Processes, 2. Olivo C.T., Machine Tool Technology and Manufacturing Processes, C Thomas Olivo and Associates 3. DeVries W.R., Analysis of Material Removal Processes, 4. Lambert B.K., Milling: Methods and Machines, Society of manufacturing Engineers, 5. A Treatise on Milling and Milling Machines, The Cincinnati Milling Machine Co., 6. Boothroyd G. & Knight W., Fundamentals of Machining and Machine Tools, 7. Mikell P. Groover, Fundamentals of Modern Manufacturing”, Third Edition 2008