Machining Processes PDF

Machining Processes Milling Dr.-Ing. Amr Nounou Introduction Milling is a basic machining process by which a surface is generated by progressive chip removal. The workpiece is fed into a rotating cutting tool or the workpiece remains stationary, and the cut...

Machining Processes Milling Dr.-Ing. Amr Nounou Introduction Milling is a basic machining process by which a surface is generated by progressive chip removal. The workpiece is fed into a rotating cutting tool or the workpiece remains stationary, and the cutter is fed to the work. Milling 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 In nearly all cases, a multiple-tooth cutter is used so that the material removal rate is high. Often the desired surface is obtained in a single pass of the cutter or work. Because very good surface finish can be obtained, milling is particularly well-suited and widely used for mass-production work. Milling 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 Many types of milling machines are used, ranging from relatively simple and flexible machines that are used for general-purpose machining in job shops and tool and die work (these are NC or CNC machines) to highly specialized machines for mass production. Unquestionably, more flat surfaces are produced by milling than by any other machining process. Milling 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 The cutting tool used in milling is known as a milling cutter. Equally spaced peripheral teeth will intermittently engage and machine the workpiece. This is called interrupted cutting. The workpieces are typically held in fixtures. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 5 Fundamentals of Milling Processes Milling, a multiple-tooth process, has two feeds: the amount of metal an individual tooth removes, called the feed per tooth, ft, (Courtesy J T. Black) and the rate at which the table translates past the rotating tool, called the table feed rate, fm, in inches per minute. It is calculated from where n is the number of teeth in a cutter and Ns is the rpm value of the cutter. Milling 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 Fundamentals of Milling Processes Milling operations can be classified into broad categories called peripheral milling, end milling, and face milling. Each has many variations. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 7 Fundamentals of Milling Processes Some basic types of milling cutters and milling operations. (a) Peripheral milling. (b) Face milling. (c) End milling. Milling Source: E Serope Kalpakjian and Steven Shmid, “Manufacturing Engineering and Technology” (6th edition), Prentice Hall, 2010. Dr.-Ing. Amr Nounou - Winter 2024-2025 8 Fundamentals of Milling Processes Peripheral Milling In peripheral milling, the surface is generated by teeth located on the periphery of the cutter body. The surface is parallel with the axis of rotation of the cutter. Both flat and formed surfaces can be produced by this method. This process, often called slab milling, is usually performed on horizontal spindle milling machines. (Courtesy J T. Black) Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 9 Fundamentals of Milling Processes Peripheral Milling Peripheral milling can be performed on a horizontal-spindle milling machine. The cutter rotates at rpm Ns, removing metal at cutting speed, V. The allowance for starting and finishing the cut depends on the cutter diameter and depth of cut, d. The feed per tooth, ft, and cutting speed are selected by the operator or process planner. (Courtesy J T. Black) Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 10 Fundamentals of Milling Processes Peripheral Milling As in the other processes, the cutting speed, V, and feed per tooth are selected by the engineer or the machine tool operator. As before, these variables depend on the work material, the tool material, and the specific process. The cutting velocity is that which occurs at the cutting edges of the teeth in the milling center. (Courtesy J T. Black) Milling 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 Milling Processes Peripheral Milling The depth of cut, called DOC or d, is simply the distance between the old and new machined surface. The width of cut is the width of the cutter or the work, in inches, and is given the symbol W. (Courtesy J T. Black) Milling 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 Milling Processes Face Milling In face milling and end milling, the generated surface is at right angles to the cutter axis. Most of the cutting is done by the peripheral portions of the teeth, with the face portions providing some finishing action. Face milling is done on both horizontal- and vertical- spindle machines. (Courtesy J T. Black) Milling 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 Milling Processes Face Milling Face milling is often performed on a vertical spindle milling machine using a multiple-tooth cutter (n = 6 teeth) rotating Ns at rpm to produce cutting speed, V. The workpiece feeds at rate fm, in inches per minute past the tool. The allowance depends on the tool diameter and the width of cut. (Courtesy J T. Black) Milling 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 Milling Processes Face Milling The tool rotates (face mills) at some rpm (Ns) while the work feeds past the tool. The rpm is related to the surface cutting speed, V, and the cutting tool diameter, D, according to equation. The depth of cut is d, in inches. The width of cut is W, in inches, and may be width of the workpiece or width of the cutter, depending on the setup. (Courtesy J T. Black) Milling 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 Milling Processes The length of the cut, L, is the length of the work plus some allowance, LA, for approach and overtravel. Milling 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 Milling Processes Milling 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 Milling Processes End Milling End milling is a very common operation performed on both vertical- and horizontal-spindle milling machines or machining centers. (a) End milling a step feature in a block using a flat-bottomed, end mill cutter in a vertical spindle-milling machine. (b) End view, table moving the block into the cutter. (c) Side view, workpiece feeding right to left into tool Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 18 Up Versus Down Milling One of the aspects of milling concerns the direction of rotation of the cutter with respect to the movement of the workpiece. Surfaces can be generated by two distinctly different methods. Up milling is the traditional way to mill and is also called conventional milling. The cutter rotates against the direction of feed of the workpiece. In climb or down milling, the cutter rotation is in the same direction as the feed rate. The method of chip formation is completely different in the two cases. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 19 Up Versus Down Milling Climb cut or down milling versus conventional cut or up milling for slab or face or end milling. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 20 Milling Surface Finish The average surface finishes that can be expected on free-machining materials range from 60 to 150 μin. Conditions exist, however, that can produce wide variations on either side of these ranges. In finishing cuts, keeping the depth of cut small will limit the axial cutting force, reducing vibrations and producing a superior finish. Milling is an interrupted cutting process. The individual teeth enter and leave the cut and subject the tool to impact loading, cyclic heating, and cycle cutting forces. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 21 Milling Surface Finish Conventional face milling (left) with cutting force diagram for Fc (right) showing the interrupted nature of the process. (From Metal Cutting Principles, 2nd ed., Ingersoll Cutting Tool Company) Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 22 Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 23 Milling Tools and Cutters Plain milling cutters used for plain or slab milling have straight or helical teeth on the periphery and are used for milling flat surfaces. The helical teeth engage the work gradually, and usually more than one tooth cuts at a given time. This reduces shock and chattering tendencies and promotes a smoother The chips are formed progressively by the teeth surface. Consequently, this type of cutter of a plain helical-tooth milling cutter during up (helical mill) usually is preferred over one milling. with straight teeth. Milling 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 24 Milling Tools and Cutters Most milling work today is done with face mills and end mills. The face mills use indexable carbide insert tooling, while the end mills are either solid HSS or insert tooling. Basically, mills are shank-type cutters having teeth on the circumferential surface and one end. They can thus be used for facing, profiling, and end milling. The teeth may be either straight or helical, but the latter is more common. Small end mills have straight shanks, whereas taper shanks are used on larger sizes. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 25 Milling Tools and Cutters Face mills have a center hole so that they can be arbor mounted. Face-milling cutters are widely used in both horizontal- and vertical-spindle machine tools and come in a wide variety of sizes (diameters and heights) and tool geometries (round, square, triangular, etc.). Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 26 Milling Tools and Cutters Face mills come in many different designs using many different insert geometries and mounting arbors. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 27 Milling Tools and Cutters Solid end mills are often coated. Insert tooling end mills come in a variety of sizes and are mounted on taper shanks. (Courtesy J T. Black) Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 28 Milling Tools and Cutters Two or more side-milling cutters often are spaced on an arbor to straddle the workpiece, also called straddle milling, and two or more parallel surfaces are machined at once. Cutter for straddle milling Source: DeGarmo's Materials and Processes in Adapted from the source: S. Kalpakjian and S.R. Schmid Manufacturing, SI Version, 12th Edition, Global (2013): Manufacturing Engineering and Technology, SI Edition, Wiley, 2017. Edition, 7th edition. Pearson Education. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 29 Milling Tools and Cutters Form milling cutters have the teeth ground to a special shape—usually an irregular contour—to produce a surface having a desired transverse contour. They must be sharpened by grinding only the tooth face, thereby retaining the original contour as long as the plane of the face remains unchanged with respect to the axis of Cutter for form milling rotation. Convex, concave, corner-rounding, and gear-tooth cutters Adapted from the source: S. Kalpakjian and S.R. Schmid are common examples. (2013): Manufacturing Engineering and Technology, SI Edition, 7th edition. Pearson Education. Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 30 Milling Tools and Cutters Slitting saws are thin, plain milling cutters, 1 3 usually from to in. thick, which have 32 16 their sides slightly “dished” to provide clearance and prevent binding. They usually have more teeth per unit of diameter than ordinary plain milling cutters and are used for milling deep narrow slots Cutters for slotting; and slitting with a milling cutter and cutting-off operations. Source: DeGarmo's Materials and Processes in Adapted from the source: S. Kalpakjian and S.R. Schmid Manufacturing, SI Version, 12th Edition, Global (2013): Manufacturing Engineering and Technology, SI Edition, Wiley, 2017. Edition, 7th edition. Pearson Education. Milling Dr.-Ing. Amr Nounou - Winter 2024-2025 31 Milling Tools and Cutters T-slot cutters are integral-shank cutters with teeth on the periphery and both sides. They are used for milling the wide groove of a T-slot. To use them, the vertical groove must first be made with a slotting mill or an end mill to provide clearance for the shank. Because the T-slot cutter cuts on five surfaces simultaneously, it must be fed (a) T-slot cutting with a milling with care. cutter. (b) A shell mill Source: DeGarmo's Materials and Processes in Source: S. Kalpakjian and S.R. Schmid (2013): Manufacturing, SI Version, 12th Edition, Global Manufacturing Engineering and Technology, SI Edition, Edition, Wiley, 2017. 7th edition. Pearson Education. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 32  Some basic types of milling cutters and milling operations. Source: Courtesy of Sandvik Coromant Milling Source: S. Kalpakjian and S.R. Schmid (2013): Manufacturing Engineering and Technology, SI Edition, 7th edition. Pearson Education. Dr.-Ing. Amr Nounou - Winter 2024-2025 33 Milling Tools and Cutters Another method of classification for face and end mill cutters relates to the direction of rotation. A right-hand cutter must rotate counterclockwise when viewed from the front end of the machine spindle. Similarly, a left-hand cutter must rotate clockwise. All other cutters can be reversed on the arbor to change them from one hand to the other. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 34 Milling Tools and Cutters Milling Source: https://www.ukocarbide.com/blog/whats-the- difference-between-left-and-right-end- mills/#:~:text=To%20judge%20whether%20the%20milling,a Dr.-Ing. Amr Nounou - Winter 2024-2025 35 %20right%2Dhand%20milling%20cutter. Retrieved; 19/11/2022 Machines for Milling Basic Milling Machine Construction Most basic milling machines are of column-and-knee construction. The column, mounted on the base, is the main supporting frame for all the other parts and contains the spindle with its driving mechanism. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 36 Machines for Milling Basic Milling Machine Construction This construction provides controlled motion of the worktable in three mutually perpendicular directions: (1) through the knee, moving vertically on ways on the front of the column; (2) through the saddle, moving transversely on ways on the knee; and (3) through the table, moving longitudinally on ways on the saddle. All these motions can be imparted by either manual or powered means. In most cases, a powered rapid traverse is provided in addition to the regular feed rates for use in setting up work and in returning the table at the end of a cut. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 37 Machines for Milling Basic Milling Machine Construction Major components of a plain column-and-knee-type milling machine, which can have horizontal spindle (shown on the left) or a turret type machine with a vertical spindle (shown on the right). The workpiece and workholder on the table can be translated in X, Y, and Z directions with respect to the tool. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 38 Machines for Milling Column-and-knee-type Machines Used for general-purpose milling operations, column-and-knee type machines are the most common milling machines. The spindle on which the milling cutter is mounted may be horizontal for peripheral milling, or vertical, for face and end milling, boring, and drilling operations. Milling Source: S. Kalpakjian and S.R. Schmid (2013): Manufacturing Engineering and Technology, SI Edition, 7th edition. Pearson Education. Dr.-Ing. Amr Nounou - Winter 2024-2025 39  Schematic illustration of (a) a horizontal-spindle column-and-knee type milling machine and (b) vertical-spindle column-and-knee type milling machine. Source: After G. Boothroyd. Milling Source: S. Kalpakjian and S.R. Schmid (2013): Manufacturing Engineering and Technology, SI Edition, 7th edition. Pearson Education. Dr.-Ing. Amr Nounou - Winter 2024-2025 40 Machines for Milling Bed-Type Milling Machines Bed-type milling machines are made for the capability of making heavy cuts. The table is mounted directly on the bed and has only longitudinal motion. The spindle head can be moved vertically in order to set up the machine for a given operation. Normally, once the setup is completed, the spindle head is clamped in position and no further motion of it occurs during machining. However, on some machines, vertical motion of the spindle occurs during each cycle. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 41 Machines for Milling Bed-Type Milling Machines Bed-type vertical-spindle heavy-duty production machine tools for milling usually have three axes of motion Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 42 Machines for Milling Bed-Type Milling Machines After such milling machines are set up, little skill is required to operate them, permitting faster learning time for the operators. Some machines of this type are equipped with automatic controls so that all the operator has to do is load and unload workpieces into the fixture and set the machine into operation. Bed-type milling machines with single spindles are sometimes called simplex milling machines; they are made with both horizontal and vertical spindles. Bed-type machines also are made in duplex and triplex types, having two or three spindles respectively, permitting the simultaneous milling of two or three surfaces at a single pass. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 43  Schematic illustration of a bed-type milling machine. Milling Source: S. Kalpakjian and S.R. Schmid (2013): Manufacturing Engineering and Technology, SI Edition, 7th edition. Pearson Education. Dr.-Ing. Amr Nounou - Winter 2024-2025 44 Machines for Milling Planer-Type Milling Machines Planer-type milling machines utilize several milling heads, which can remove large amounts of metal while permitting the table and workpiece to feed quite slowly. Often only a single pass of the workpiece past the cutters is required. Large planer-type milling machines share their basic design with that of Through the use of different types of milling heads and a planer with the planing tool cutters, a wide variety of surfaces can be machined with a replaced by a powered milling head single setup of the workpiece. (not shown). (American Machinist Special Report to Fundamentals of Milling, J This is an advantage when heavy workpieces are involved. Jablonowski, Feb, 1978) Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 45 Machines for Milling Milling Machine Selection When purchasing or using a milling machine, consider the following issues: 1.Spindle orientation and rpm. 2.Machine capability (accuracy and precision). 3.Machine capacity (size of workpieces). 4.Horsepower available at spindle (usually 70% of machine horsepower). 5.Automatic tool changing. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 46 Machines for Milling Accessories for Milling Machines The usefulness of ordinary milling machines can be greatly extended by employing various accessories or attachments. A horizontal milling machine can be equipped with a vertical milling attachment to permit vertical milling to be done. Ordinarily, heavy cuts cannot be made with such an attachment. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 47 Machines for Milling Accessories for Milling Machines A universal milling attachment is similar to the vertical attachment but can be swiveled about both the axis of the milling machine spindle and a second, perpendicular axis to permit milling to be done at any angle. The universal dividing head is by far the most widely used milling machine accessory, providing a means for End milling a helical groove on a holding and indexing work through any desired arc of horizontal-spindle milling machine using a rotation. universal dividing head and a universal The work may be mounted between centers or held in a milling attachment. chuck that is mounted in the spindle hole of the dividing (Courtesy of Cincinnati Milacron, Inc.) head. Milling Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 48 Enhance your German terminology … English term German term Milling Fräsen Movement Bewegung Horizontal Waagerecht Vertical Senkrecht Milling Dr.-Ing. Amr Nounou - Winter 2024-2025 49  Thank you for your attention... Milling Dr.-Ing. Amr Nounou - Winter 2024-2025 50