Machining Processes PDF

Machining Processes Turning and Boring Processes Dr.-Ing. Amr Nounou Introduction Turning is the process of machining external cylindrical and conical surfaces. It is usually performed on a machine tool called a lathe. Relatively simple work and tool movements are invol...

Machining Processes Turning and Boring Processes Dr.-Ing. Amr Nounou Introduction Turning is the process of machining external cylindrical and conical surfaces. It is usually performed on a machine tool called a lathe. Relatively simple work and tool movements are involved in turning a Schematic of a standard engine lathe performing a turning cylindrical surface. operation, with the cutting tool shown in inset. (Courtesy J T. Black) Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 2 Introduction The workpiece is rotated and the single-point cutting tool is fed longitudinally into the workpiece and then travels parallel to the axis of workpiece rotation, reducing the diameter by the depth of cut (DOC). Basics of the turning process normally done on a lathe. The dashed arrows indicate the feed motion of the tool relative to the work. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 3 Introduction The tool feeds at a rate, fr, cutting at a speed, V, in units of surface feet per minute (sfpm), which is used to determine the revolutions per minute (rpm) of the workpiece. Basics of the turning process normally done on a lathe. The dashed arrows indicate the feed motion of the tool relative to the work. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 4 Introduction Basic turning machines can rotate the work and feed the tool longitudinally for turning and can perform other operations by feeding transversely. Depending on what direction the tool is fed and on what portion of the rotating workpiece is being machined, the operations have different names. The dashed arrows indicate the tool feed motion relative to the workpiece. (Courtesy J T. Black) Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 5 Introduction If the tool is fed at an angle to the axis of rotation, an external conical surface results. This is called taper turning. If the tool is fed to the axis of rotation, using a tool that is wider than the depth of the cut, the operation is called facing, and a flat surface is produced on the end of the cylinder. (Courtesy J T. Black) Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 6 Introduction By using a tool having a specific form or shape and feeding it radially or inward against the work, external cylindrical, conical, and irregular surfaces of limited length can also be turned. The shape of the resulting surface is (Courtesy J T. Black) determined by the shape and size of the cutting tool. Such machining is called form turning. Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 7 Introduction If the tool is fed all the way to the axis of the workpiece, it will be cut in two. This is called parting or cutoff, and a simple, thin tool is used. A similar tool is used for necking or partial cutoff. (Courtesy J T. Black) Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 8 Introduction Boring is a variation of turning. Essentially, boring is internal turning. Boring can use single-point cutting tools to produce internal cylindrical or conical surfaces. It does not create the hole but, rather, machines or opens the hole up to a specific size. Boring can be done on most machine tools that can do turning. (Courtesy J T. Black) Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 9 Introduction Other operations, such as threading and knurling, can be done on machines used for turning. (Courtesy J T. Black) Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 10 Introduction In addition, drilling can be done on the rotation axis of the work. (Courtesy J T. Black) Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 11 Fundamentals of Turning, Boring, and Facing Turning Turning constitutes the majority of lathe work. If good finish and accurate size are desired, one or more roughing cuts are usually followed by one or more finishing cuts. In roughing cuts, large depths of cut are used. Finishing cuts are light, usually being less than 0.015 in. in depth, with the feed as fine as necessary to give the desired finish. In most cases, one finishing cut is all that is required. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 12 Fundamentals of Turning, Boring, and Facing Turning To determine the inputs to the machines, the depth of cut, cutting speed, and feed rate must be selected. The desired cutting speed establishes the necessary rpm (Ns) of the rotating workpiece. The feed fr is given in inches per revolution (ipr). The depth of cut is d, where Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 13 Fundamentals of Turning, Boring, and Facing Turning The inputs to the turning process are determined as follows; Based on the material being machined and the cutting tool material being used, the engineer selects the cutting speed, V, in feet per minute, the feed (fr), and the depth of cut. The rpm value for the machine tool can be determined by calculating Ns, (using the larger diameter), where the factor of 12 is used to convert feet to inches. Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 14 Fundamentals of Turning, Boring, and Facing Turning The length of cut is the distance traveled parallel to the axis L plus some allowance or overrun A to allow the tool to enter and/or exit the cut. The cutting time is where A is overrun allowance and fr is the selected feed in inches per revolution Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 15 Fundamentals of Turning, Boring, and Facing Turning The metal removal rate (MRR) is An approximate equation that assumes that the depth of cut d is small compared to the uncut diameter D1. Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 16 Fundamentals of Turning, Boring, and Facing Turning Basic movement of boring, facing, and cutoff in a lathe, where cutting is performed by one- single-point cutting tool at a time and the tool can be fed in any direction. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 17 Fundamentals of Turning, Boring, and Facing Turning Boring Boring always involves the enlarging of an existing hole, which may have been made by drilling or may be the result of a core in a casting. Holes may be bored straight, tapered, with threads, or to irregular contours. Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 18 Fundamentals of Turning, Boring, and Facing Turning Boring As before V and fr are selected. For a cut of length L, the cutting time is where for D1, the diameter of bore, and A, the overrun allowance. The metal removal rate is where D2 is the original hole diameter; (omitting allowance term), where d is the depth of cut. Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 19 Fundamentals of Turning, Boring, and Facing Turning Facing Facing is the producing of a flat surface as the result of the tool being fed across the end of the rotating workpiece. Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 20 Fundamentals of Turning, Boring, and Facing Turning Facing The cutting speed should be determined from the largest diameter of the surface to be faced. In facing, the tool feeds perpendicular to the axis of the rotating workpiece. Because the rpm is constant, the cutting speed is continually decreasing as the axis is approached. The length of cut L is D1/2 or (D1 – D2)/2 for a tube. where d is the depth of cut and L = D1/2 is the length of cut. Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 21 Fundamentals of Turning, Boring, and Facing Turning Parting Parting is the operation by which one section of a workpiece is disconnected from the remainder by means of a cutoff tool. The tool should be set exactly at the height of the axis of rotation, be kept sharp, have proper clearance angles, and be fed into the workpiece at a proper and uniform feed rate. The tool is fed (plunged) perpendicular to the rotational axis, as it was in facing. The length of cut for solid bars is D1/2. For tubes, In cutoff operations, the width of the tool is d in inches, the width of the cutoff operation. The equations for Tm and MRR are then basically the same as for facing. Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 22 Fundamentals of Turning, Boring, and Facing Turning Drilling Drilling can be done on lathes with the drill mounted in the tailstock quill of engine lathes or the turret on turret lathes and fed against a rotating workpiece. Coolants should be used where required. In drilling deep holes, the drill should be withdrawn occasionally to clear chips from the hole and to aid in getting coolant to the cutting edges. This is called peck drilling. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 23 Lathe Design and Terminology Knowing the terminology of a machine tool is fundamental to understanding; - how it performs the basic operations, - how the workholding devices are interchanged, - and how the cutting tools are mounted and interfaced to the work. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 24 Lathe Design and Terminology Lathes are machine tools designed primarily to do turning, facing, and boring. Very little turning is done on other types of machine tools, and none can do it with equal ability. Lathes also can do drilling. Consequently, the lathe is probably the most common machine tool, along with milling machines. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 25 Lathe Design and Terminology Lathe Design The essential components of an engine lathe are the bed, headstock assembly (which includes the spindle), tailstock assembly, carriage assembly, quick-change gearbox, and the leadscrew and feed rod. Schematic of an engine lathe, a versatile machine tool that is easy to set up and operate and is intended for short-run jobs. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 26 Lathe Design and Terminology Lathe Design – the bed The bed is the base and backbone of a lathe. Two sets of parallel, longitudinal ways, inner and outer, are contained on the bed. Any inaccuracy in them usually means that the accuracy of the entire lathe is destroyed. Schematic of an engine lathe, a versatile machine tool that is easy to set up and operate and is intended for short-run jobs. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 27 Lathe Design and Terminology Lathe Design – the headstock The headstock, mounted in a fixed position on the inner ways, provides powered means to rotate the work at various rpm values. Essentially, it consists of a hollow spindle, mounted in accurate bearings, and a set of transmission gears through which the spindle can be rotated at a number of speeds. The spindle protrudes from the gearbox and Schematic of an engine lathe, a versatile machine tool contains means for mounting various types of that is easy to set up and operate and is intended for workholding devices (chucks, face and dog short-run jobs. plates, collets). Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 28 Lathe Design and Terminology Lathe Design – the tailstock The tailstock assembly consists, essentially, of three parts. A lower casting fits on the inner ways of the bed, can slide longitudinally, and can be clamped 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, to permit aligning the tailstock and headstock spindles (for turning tapers). Schematic of an engine lathe, a versatile machine tool that is easy to set up and operate and is intended for The third major component of the assembly is the short-run jobs. tailstock quill which is a hollow steel cylinder. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 29 Lathe Design and Terminology Lathe Design – the carriage assembly The carriage assembly, together with the apron, provides the means for mounting and moving cutting tools. The carriage, a relatively flat H-shaped casting, rides on the outer set of ways on the bed. The cross slide is mounted on the carriage and can be moved by means of a feed screw that is controlled by a small handwheel and a graduated dial. The cutting tools for lathe work are held in the tool post on the compound rest, which can translate and swivel. (Courtesy J T. Black) Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 30 Lathe Design and Terminology Lathe Design On most lathes, the tool post is mounted on a compound rest. The compound rest can rotate and translate with respect to the cross slide, permitting further positioning of the tool with respect to the work. The apron, attached to the front of the carriage, has the controls for providing manual and powered motion for the carriage and powered motion for the cross slide. The cutting tools for lathe work are held in the tool The carriage is moved parallel to the ways by post on the compound rest, which can translate and turning a handwheel on the front of the apron. swivel. (Courtesy J T. Black) Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 31 Lathe Design and Terminology Size Designation of Lathes The size of a lathe is designated by two dimensions. The first is known as the swing. This is the maximum diameter of work that can be rotated on a lathe. The second size dimension is the maximum distance between centers. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 32 Lathe Design and Terminology Types of Lathes Lathes used in manufacturing can be classified as speed, engine, toolroom, turret, automatics, tracer, and numerical control turning centers. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 33 Lathe Design and Terminology Types of Lathes – Engine lathes Engine lathes are the type most frequently used in manufacturing. They are heavy-duty machine tools with all the components described previously and have power drive for all tool movements except on the compound rest. Although engine lathes are versatile and very useful, the time required for changing and setting tools and for making measurements on the workpiece is often a large percentage of the cycle time. Schematic of an engine lathe, a versatile machine tool that is easy to set up and operate and is Turret lathes, and other types of semiautomatic intended for short-run jobs. and automatic lathes have been highly developed and are widely used in manufacturing as another means to improve cutting productivity. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 34 Lathe Design and Terminology Types of Lathes – Turret Lathes Basically, a longitudinally feedable, hexagon turret replaces the tailstock. The turret, on which six tools can be mounted, can be rotated to bring each tool into operating position, and the entire unit can be translated parallel to the ways to provide feed for the tools. Turret lathe Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 35 Lathe Design and Terminology Types of Lathes – Turret Lathes The square turret on the cross slide can be rotated manually about a vertical axis to bring each of the four tools into operating position. On most machines, the turret can be moved transversely, either manually or by power, by means of the cross slide, and longitudinally through power or manual operation of the carriage. Turret lathe In most cases, a fixed tool holder also is added to the back end of the cross slide; this often carries a parting tool. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 36 Lathe Design and Terminology Types of Lathes – Turret Lathes Through these basic features of a turret lathe, a number of tools can be set up on the machine and then quickly be brought successively into working position. In this way, a complete part can be machined without the necessity for further adjusting, changing tools, or making measurements. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 37 Cutting Tools for Lathes Lathe Cutting Tools Because tool materials are expensive, it is desirable to use as little as possible. At the same time, it is essential that the cutting tool be supported in a strong, rigid manner to minimize deflection and possible vibration. Consequently, lathe tools are supported in various Common types of forged tool holders: types of heavy, forged (a) right-hand turning, (b) facing, (c) grooving cutoff, steel tool holders. (d) boring, (e) threading. (Courtesy of Armstrong Industrial Hand Tools) Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 38 Cutting Tools for Lathes Lathe Cutting Tools Typical insert shapes, available cutting edges per insert, and insert holders for throwaway insert cutting tools. (Adapted from Turning Handbook of High Efficiency Metal Cutting, Courtesy Armstong Industrial Hand Tools) Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 39 Cutting Tools for Lathes Lathe Cutting Tools When lathes are incorporated into lean manufacturing cells where many different operations are performed, the time required for changing and setting tools may constitute as much as 50% of the total cycle time. Quick-change tool holders can reduce the manual tool-changing time. The individual tools, preset in their holders, can be interchanged in the special tool post in a few seconds. With some systems, a second tool may be set in the tool post while a cut is being made with the first tool and can then be brought Quick-change tool post and accompanying tool holders. into proper position by rotating the post. (Courtesy of Armstong Industrial Hand Tools) Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 40 Cutting Tools for Lathes Turret-Lathe Tools Turret-lathe tooling setup for producing part shown. Numbers in circles indicate the sequence of the operations from 1 to 9. The letters A through F refer to the surfaces being machined. Operation 3 is a combined operation. The roll turner is turning surface F, while tool 3 on the square post is turning surface B. The first operation stops the stock at the right length. The last operation cuts the finished bar off and puts a chamfer on the bar, which will next be advanced to the stock stop. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 41 Workholding in Lathes Workholding Devices for Lathes Five methods are commonly used for supporting workpieces in lathes: 1.Held between centers. 2.Held in a chuck. 3.Held in a collet. 4.Mounted on a faceplate. 5.Mounted on the carriage. In the first four of these methods, the workpiece is rotated during machining. In the fifth method, which is not used extensively, the tool rotates while the workpiece is fed into the tool. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 42 Workholding in Lathes Workholding Devices for Lathes Lathe Centers Workpieces that are relatively long with respect to their diameters are usually held between centers. Two lathe centers are used, one in the spindle hole and the other in the hole in the tailstock quill. Before a workpiece can be mounted between lathe centers, a center hole Work being turned between centers in a lathe, showing the must be drilled in each end. use of a carriage (dog) and catch plate (dog plate). (Courtesy of South Bend Lathe) Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 43 Workholding in Lathes Workholding Devices for Lathes Lathe Centers Because the work and the center of the headstock end rotate together, no lubricant is needed in the center hole at this end. The center in the tailstock quill does not rotate; adequate lubrication must be provided. Live centers are often used in the Work being turned between centers in a lathe, showing the use of a tailstock to overcome these carriage (dog) and catch plate (dog plate). problems. (Courtesy of South Bend Lathe) Turning and Boring Processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 44 Workholding in Lathes Workholding Devices for Lathes Lathe Chucks Lathe chucks are used to support a wider variety of workpiece shapes and to permit more operations to be performed (than held between centers). Two basic types of chucks are used, three-jaw and four-jaw. The jaws on chucks for lathes (four-jaw independent or three-jaw self- centering) can be removed and reversed. Turning and Boring Processes Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 45 Enhance your German terminology … English term German term Turning Drehen Diameter Durchmesser Length Länge Speed Geschwindigkeit Turning and Boring Processes Dr.-Ing. Amr Nounou - Winter 2024-2025 46  Thank you for your attention... Turning and Boring Processes Dr.-Ing. Amr Nounou - Winter 2024-2025 47