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ENM208

ENM208. INTRODUCTION to MACHINING ANADOLU UNİVERSITY Industrial Engineering Department. Manufacturing Processes. Introduction To Machining. Machining is the process of removing unwanted material from a workpiece in the form of chips.

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ENM208

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  1. ENM208 • INTRODUCTION to MACHINING • ANADOLU UNİVERSITY • Industrial Engineering Department

  2. Manufacturing Processes Introduction To Machining Machining is the process of removing unwanted material from a workpiece in the form of chips. Machining is capable of creating geometric configurations, tolerances, and surface finishes often unobtainable by any other manufacturing processes Machining is the most important of the basic manufacturing processes. If the workpiece is metal, the process is often called Metal Cutting or Metal Removal. Spring 2005

  3. Manufacturing Processes Machining and Precision Because of the increased demand for high quality, precision machining is becoming common and hence the need for high accuracy measurement systems. Spring 2005

  4. Manufacturing Processes Examples of Machined Parts Spring 2005

  5. Manufacturing Processes Inputs to Machining Processes The machining process is complex because it has such a wide variety of inputs which are listed as follows: • The machine tool selected to perform the process. • The cutting tool selected (geometry and material). • The properties and parameters of the workpiece. • The cutting parameters selected (cutting speed, feed rate, and depth of cut). • The workpiece holding devices or fixtures. Spring 2005

  6. Types of Machining Operations

  7. Types of Machining Operations

  8. Manufacturing Processes Turning Operations Turning is the process of machining external cylindrical and conical surfaces. The process uses a machine tool called a lathe. Spring 2005

  9. Manufacturing Processes Lathe Machine The Centre Lathe is used to manufacture cylindrical shapes from a range of materials Spring 2005

  10. Manufacturing Processes Lathe Machine Lathe Machine Characteristics • Swing - maximum diameter that can be rotated on the lathe. • Maximum distance between centers • Power of the lathe engine. • Rotational speed range. • Feed Rate range. Spring 2005

  11. Manufacturing Processes Lathe Operations Turning Operations To produce straight, conical, formed, or grooved workpieces such as shafts, spindles and pins Spring 2005

  12. Manufacturing Processes Lathe Operations Facing Operations To produce flat surface at the end of the part, which are useful for parts that are attached to other components. Spring 2005

  13. Manufacturing Processes Lathe Operations Boring Operations To enlarge hole or cylindrical cavity made by a previous process or to produce circular internal grooves Spring 2005

  14. Manufacturing Processes Lathe Operations Parting or Cutting off Operations To cut a piece from the end of a part Spring 2005

  15. Manufacturing Processes Lathe Operations Drilling To produce a hole, which may be followed by boring to improve its accuracy and surface finish Spring 2005

  16. Manufacturing Processes Lathe Operations Threading To produce external or internal threads Spring 2005

  17. Manufacturing Processes Lathe Operations Knurling Operations To produce a regularly shaped roughness on cylindrical surfaces Spring 2005

  18. Manufacturing Processes Cutting Tools for Lathe Operations Single Point Cutting Tools Spring 2005

  19. Manufacturing Processes Single Point Cutting Tool Geometry Spring 2005

  20. Manufacturing Processes Turning Tool Angles Spring 2005

  21. Manufacturing Processes Cutting-Tool Materials The selection of cutting-tool materials for a particular application is among the most important factors in machining operations The cutting tool is subjected to: (a) high temperatures; (b) contact stresses, and (c) sliding along the tool-chip interface and along the machined surface. A cutting tool material must possess the following characteristics: Hardness, so that the hardness, strength, and wear resistance of the tool are maintained at the temperature encountered in cutting operations. Toughness, so that impact forces on the tool or due to vibration during machining do not fracture the tool. Wear resistance, so that an acceptable tool life is obtained before the tool is indexed or replaced. Spring 2005

  22. Manufacturing Processes Cutting-Tool Materials Various cutting-tool materials with a wide range of mechanical, physical, and chemical properties are available. Tool materials are usually divided into the following general categories: 1- Carbon and medium-alloy steels. 2- High-speed steels. 3- Carbides (coated and uncoated). 4- Ceramics. 5- Diamond. Spring 2005

  23. Manufacturing Processes Characteristics of Cutting-tool Materials Spring 2005

  24. Manufacturing Processes Workholding on a Lathe You cannot perform accurate work if the workpiece is improperly mounted. The requirements for proper mounting are as follows: 1- The work center line must be accurately centered along the axis of the lathe spindle. 2- The work must be held rigidly while being turned. 3- The work mustNOTbe sprung out of shape by the holding device. 4-The work must be adequately supported against any deflection caused by its own weight and against springing caused by the action of the cutting tool. Spring 2005

  25. Manufacturing Processes Workholding on a Lathe • There are four general methods of holding work in the lathe: • between centers, • (2) In a chuck, • (3) on a mandrel, and • (4) on a faceplate. Spring 2005

  26. Manufacturing Processes Turning Parameters 1- Cutting 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 (m/min). 2- Feed (f) is the amount of material removed per revolution or per pass of the tool over the workpiece. In turning, feed is in millimeter per revolution (mm/r), and the tool feeds parallel to the rotational axis of the workpiece. 3- Depth of Cut (d) It is the distance the tool is plunged into the surface. In turning, it is half the difference between initial and final diameters given in (mm). Spring 2005

  27. Manufacturing Processes Selection of Cutting Speed Selection of Cutting Speed depends on three factors: 1- Operation Type. 2- Workpiece Material 3- Tool Material Spring 2005

  28. Manufacturing Processes Selection of Feed Rate Selection of Feed Rate depends on three factors: 1- Operation Type. 2- Workpiece Material 3- Tool Material Spring 2005

  29. Manufacturing Processes Roughing and Finishing Cuts In machining the general procedure is to (a) Perform one or more roughing cuts at low speed, fast feed rate and large depth of cut (little consideration of dimensional tolerances and surface finish), and V f d (b) Follow it with a finishing cut a higher speed, slower feed rate and smaller depth of cut for a good surface finish. V f d Spring 2005

  30. Manufacturing Processes Summary of Turning Parameters and Formulas Spring 2005

  31. Manufacturing Processes Drilling and Related Hole Making Operations Spring 2005

  32. Manufacturing Processes Hole Making Processes Various Types of Drilling and Reaming Operations Spring 2005

  33. Manufacturing Processes Drilling Sequence The Most Accurate holes are produced by the following sequence of operations: 1- Center drilling. 2- Drilling. 3- Boring, and 4- Reaming. Spring 2005

  34. Manufacturing Processes Drilling Operation Drillingis the process of producing or enlarging a hole. This is accomplished by rotating the tool and/or workpiece. Spring 2005

  35. Manufacturing Processes Reaming Reaming - Enlarging an existing hole with a multi-edged tool (reamer) for dimensional accuracy and/or surface finish Spring 2005

  36. Manufacturing Processes Countersinking Operation Countersinking - operation for producing a tapered feature at the end of a hole. Most popular application is a feature for a flathead screw (82 degrees). Spring 2005

  37. Manufacturing Processes Counterboring Operation • Counterboring - Enlarging of an existing hole at one end. This enlarged hole is concentric with the existing hole and is flat at the bottom. One application of this process is a feature to set the head of a bolt below a surface. Spring 2005

  38. Manufacturing Processes Center Drilling Center Drilling – is an operation used to start a hole at the desired location on a surface or to produce the hole at the end of a piece of stock so that it may be mounted between centers in a lathe. Spring 2005

  39. Manufacturing Processes Tapping Tapping – an operation used to produce internal thread in workpieces. Spring 2005

  40. Manufacturing Processes Drilling Machines Spring 2005

  41. Manufacturing Processes Drilling Tools Most Commonly used Spring 2005

  42. Manufacturing Processes Reamer Spring 2005

  43. Manufacturing Processes Drilling Parameters • - Given hole diameter, D (mm), • - Given hole length, L (mm), • - Select cutting speed, V (m/min), • - Select feed, f (mm/r), • Rotational speed, (rpm) • Feed speed, (mm/min) • Machining time, (min) (mm3/min) • Metal removal rate, Spring 2005

  44. Manufacturing Processes Recommended speeds and feeds Spring 2005

  45. Manufacturing Processes Workholding in Drilling Workholding devices for drilling are important to ensure that the workpiece can be located properly. • Vise • Angle plate • Jig • Clamp to table of drill press Spring 2005

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