Fundamentals of Machining PDF 2024-2025

Machining Processes Fundamentals of Machining Dr.-Ing. Amr Nounou Tips and Important Remarks - Attending the Lecture is very important - Lecture slides and Lecture notes are to be studied for the Assessments - Participate actively in the Lecture - Also write down y...

Machining Processes Fundamentals of Machining Dr.-Ing. Amr Nounou Tips and Important Remarks - Attending the Lecture is very important - Lecture slides and Lecture notes are to be studied for the Assessments - Participate actively in the Lecture - Also write down your notes during the lecture and revise them for the Assessments Fundamentals of Machining 2 Dr.-Ing. Amr Nounou - Winter 2024-2025 Introduction Machining is the process of removing unwanted material from a workpiece in the form of chips. If the workpiece is metal, the process is often called metal cutting or metal removal. Source: https://www.robotics247.com/article/hexagon- Source: DeGarmo's Materials and Processes in releases-new-machine-simulation-software Manufacturing, SI Version, 12th Edition, Global Retrieved: 17/09/2023 Edition, Wiley, 2017. Fundamentals of Machining Dr.-Ing. Amr Nounou - Winter 2024-2025 3 Processing families with subgroups and typical processes Adapted from the source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. 4 Fundamentals of Machining Dr.-Ing. Amr Nounou - Winter 2024-2025 Introduction The majority of manufactured products require machining at some stage in their production, ranging from relatively rough or nonprecision work, such as cleanup of castings or forgings, to high-precision work involving tolerances of 0.0001 in. or less- and high-quality finishes. Thus, machining undoubtedly is the most important of the basic manufacturing processes. Fundamentals of Machining Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 5 GIU Lathe machine Milling machine Drilling machine Fundamentals of Machining Dr.-Ing. Amr Nounou - Winter 2024-2025 6 GIU CNC milling machine Fundamentals of Machining Dr.-Ing. Amr Nounou - Winter 2024-2025 7 Fundamentals The process of metal cutting is complex because it has such a wide variety of inputs The machine tool (machine) selected to perform the process. The cutting tool selected (geometry and material). The properties and parameters of the workpiece. The cutting parameters selected (speed, feed, depth of cut). The workpiece holding devices or fixtures or jigs. Fundamentals of Machining 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  The fundamental inputs and outputs to machining processes. Fundamentals of Machining 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 There are seven basic chip formation processes are: Turning Milling Drilling Sawing Broaching Shaping and planing Grinding (also called abrasive machining) Fundamentals of Machining Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 10  The basic machining processes used in chip formation are widely varied. Fundamentals of Machining Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 11 For all metal-cutting processes, it is necessary to determine the cutting parameters of speed, feed, and depth of cut. The turning process will be used to introduce these terms. Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Source: https://metalworking.in/mastercam- Edition, Wiley, 2017. milling-turning-and-mill-turn-what-are-the- differences/ Retrieved: 17/09/2023 Fundamentals of Machining Dr.-Ing. Amr Nounou - Winter 2024-2025 12 In general, speed (V) is the primary cutting motion, which relates the velocity of the cutting tool relative to the workpiece. It is generally given in units of surface feet per minute (sfpm), inches per minute (in./min), meters per minute (m/m), or meters per second (m/s). Fundamentals of Machining 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 Feed (fr) is the amount of material removed per revolution or per pass of the tool over the workpiece. In turning, feed is in inches per revolution, and the tool feeds parallel to the rotational axis of the workpiece for the turning process. Depending on the process, feed units are inches per revolution, inches per cycle, inches per minute, or inches per tooth. Fundamentals of Machining 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 The depth of cut (DOC) represents the third dimension. In turning, it is the distance the tool is plunged into the surface. It is half the difference in the initial diameter, D1, and the final diameter, D2: Fundamentals of Machining 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 The selection of the cutting speed V determines the surface speed of the rotating part that is related to the outer diameter of the workpiece. Note: 1 foot = 12 inches where D1 is in inches, V is speed in surface feet per minute, and Ns is the revolutions per minute (rpm) of the workpiece. The operator inputs the desired revolutions per minute (rpm) of the spindle into the lathe to produce the desired cutting velocity. Fundamentals of Machining 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 The selection of the cutting tool material and geometry determines the selection of the cutting speed. That is, the cutting tool is used to machine the workpiece (i.e., form chips) and is the most critical component. For the lathe, the input parameters are DOC, the feed rate, and the rpm value of the spindle. The rpm value depends on the selection of the cutting speed, V. Rewriting equation for Ns: Once cutting speed (V) has been selected, this equation is used to determine the spindle rpm, Ns. Fundamentals of Machining 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 17 Tables of recommended values, as shown are good starting points. The table given is only a sample. For industrial calculations, standard references listed at the end of the book or cutting tool manufacturers should be consulted. Examples of a table for selection of speed and feed for turning. (Source: Metcut’s Machinability Data Handbook) Fundamentals of Machining Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. 18 Dr.-Ing. Amr Nounou - Winter 2024-2025 The selection of values of cutting speed, feed rate, and DOC depend on many factors, and a great deal of experience and experimentation are required to find the best combinations. This table is for turning processes only. This table provides recommendations of V and fr in both English and metric units based on the DOC needed to perform the job. Table values are usually conservative and should be considered starting points for determining the operational parameters for a process. Fundamentals of Machining Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 19 The speed and feed can be used with the DOC to estimate the metal removal rate for the process, or MRR. For turning, the MRR is This is an approximate equation for MRR. For turning, MRR values can range from 0.1 to 600 in.3/min. The MRR can be used to estimate the horsepower needed to perform a cut, as will be shown later. For most processes, the MRR equation can be viewed as the volume of metal removed divided by the time needed to remove it: where Tm is the cutting time in minutes. For turning, the cutting time depends on the length of cut L divided by the rate of traverse of the cutting tool past the rotating workpiece frNs in inches/minute. Therefore, Fundamentals of Machining 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 Basic Machining Processes Turning is an example of a single-point tool process. Milling, and drilling are examples of multiple-point tool processes. Source: https://trimantec.com/blogs/t/machining- Source: DeGarmo's Materials and Processes in processes-overview Manufacturing, SI Version, 12th Edition, Global Retrieved: 17/09/2023 Edition, Wiley, 2017. Fundamentals of Machining Dr.-Ing. Amr Nounou - Winter 2024-2025 21 Forces and Power in Machining Most of the cutting operations process described to this point are examples of oblique or three-force cutting. Fc: Primary cutting force acting in the direction of the cutting velocity vector. This force is generally the largest force and accounts for 99% of the power required by the process. Ff: Feed force acting in the direction of the tool feed. This force is usually about 50% of Fc but accounts for only a small percentage of the power required because feed rates are usually small compared to cutting speeds. Fr: radial or thrust force acting perpendicular to the machined surface. Fundamentals of Machining 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 Forces and Power in Machining In general, increasing the speed, the feed, or the depth of cut will increase the power requirement. Doubling the speed doubles the horsepower directly. Doubling the feed or the depth of cut doubles the cutting force, Fc. In general, increasing the speed does not increase the cutting force, Fc, a surprising experimental result. However, speed has a strong effect on tool life because most of the input energy is converted into heat, which raises the temperature of the chip, the work, and the tool. The cutting force system in a conventional, oblique-chip formation process is shown. Oblique (three-force) machining has three measurable components of forces acting on the tool. Fundamentals of Machining Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 23 Forces and Power in Machining The power required for cutting is The horsepower at the spindle of the machine is therefore In metal cutting, a very useful parameter is called the unit, or specific, horsepower, HPs, which is defined as In turning, for example, where then Thus, this term represents the approximate power needed at the spindle to remove a cubic inch of metal per minute. Fundamentals of Machining Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 24 Chip Formation Basically, the chip is formed by a localized shear process that takes place over a very narrow zone. Schematic representation of the material flow, that is, the chip-forming shear process. Here, ϕ defines the onset of shear or lower boundary and ψ defines the direction of slip due to dislocation movement. Fundamentals of Machining Source: DeGarmo's Materials and Processes in Manufacturing, SI Version, 12th Edition, Global Edition, Wiley, 2017. Dr.-Ing. Amr Nounou - Winter 2024-2025 25 Fundamentals of Machining Source: TURN TUTORIAL, SOLIDWORKS CAM 2022 Dr.-Ing. Amr Nounou - Winter 2024-2025 26 Fundamentals of Machining Source: Mill Tutorial, SOLIDWORKS CAM 2022 Dr.-Ing. Amr Nounou - Winter 2024-2025 27 Enhance your German terminology … English term German term Machining processes Bearbeitungsprozesse Turning Drehen Drilling Bohren Milling Fräsen Sawing Sägen Cutting parameters Schneidparameter Speed Geschwindigkeit Depth of cut Schnitttiefe Strain Belastung Tensile strength Zugfestigkeit Fundamentals of Machining Dr.-Ing. Amr Nounou - Winter 2024-2025 28  Thank you for your attention... Fundamentals of Machining Dr.-Ing. Amr Nounou - Winter 2024-2025 29