I unit -_introduction_to_unconventional_machining_processes
- 2. History of Machining 2 In ancient days – hand tools (stones, bones or stick). Later – hand tools of elementary metals (bronze or iron) Till 17th Century – tools were either hand operated or driven mechanically by very elementary methods. Wagons, ships, furniture, etc. – were produced. Introduction of water, steam and electricity – power driven machine tools Caused a big revolution in 18th and 19th centuries. 1953 – Numerical control machine tools – enhanced the product productivity and accuracy.
- 3. DEMERITS OF CONVENTIONAL MACHINING PROCESSES 3
- 4. UNCONVENTIONAL MANUFACTURING PROCESS 4 Non –Traditional Machining Process or Un-Conventional Machining Process Unconventional Forming Process
- 7. Traditional or Conventional Machining 7
- 9. Abrasive Machining 9 Cylindrical grinding Flat surface grinding
- 11. Need for Unconventional Machining 11 • Greatly improved thermal, mechanical and chemical properties of modern materials – Not able to machine through conventional methods. (Why???) • Ceramics & Composites – high cost of machining and damage caused during machining – big hurdles to use these materials. • In addition to advanced materials, more complex shapes, low rigidity structures and micro-machined components with tight tolerances and fine surface finish are often needed. • To meet these demands, new processes are developed. • Play a considerable role in aircraft, automobile, tool, die and mold making industries.
- 12. Need for Unconventional Machining 12 • Very high hardness and strength of the material. (above 400 HB.) • The work piece is too flexible or slender to support the cutting or grinding forces. • The shape of the part is complex, such as internal and external profiles, or small diameter holes. • Surface finish or tolerance better than those obtainable conventional process. • Temperature rise or residual stress in the work piece are undesirable.
- 13. 13 Unconventional Machining Processes - Classification Electrical
- 14. Mechanical Based Processes 14 AJM - Abrasive Jet Machining WJM – Water Jet Machining AWJM – Abrasive Water Jet Machining USM – Ultrasonic Machining
- 15. 15 Electrical Based Processes Electrical EDM - Electrical Discharge Machining WEDM - Wire Cut Electrical Discharge Machining
- 16. 16 Chemical & Electrochemical Based Processes ECM - Electro –Chemical Machining ECD - Electro Chemical Deburring ECG – Electro –Chemical Grinding ECH – Electro – Chemical Honing
- 17. 17 Thermal Based Processes LBM - Laser Beam Machining PAM – Plasma Arc Machining EBM - Electron Beam Machining
- 18. Mechanical based Unconventional Processes 18 USM – thru mechanical abrasion in a medium (solid abrasive particles suspended in the fluid) WJM – Cutting by a jet of fluid AWJM – Abrasives in fluid jet. IJM – Ice particles in fluid jet. Abrasives or ice – Enhances cutting action.
- 19. CLASSIFICATION
- 24. Thermal based Unconventional Processes 24 Thru – melting & vaporizing Heat Source: Plasma – EDM and PBM. Photons – LBM Electrons – EBM Ions – IBM Machining medium: different for different processes.
- 25. . 25
- 26. ELECTRO CHEMICAL ENERGY METHODS 26 CHEMICAL ENERGY METHODS These methods involve controlled etching of the work piece material in contact with a chemical solution
- 27. Chemical & Electrochemical based Unconventional Processes 27 CHM – uses Chemical dissolution action in an etchant. ECM – uses Electrochemical dissolution action in an electrolytic cell.
- 28. MATERIAL – METHOD OF MACHINING 28
- 29. PROCESS SELECTION 29 Based on the following points 1. Physical Parameters 2. Shapes to be machined 3. Process Capability or Machining Characteristics 4. Economic Considerations
- 32. 32 Process Capability or Machining Characteristics 1. Material Removal rate 2. Tolerance Maintained 3. Surface Finish 4. Depth of surface Damage 5. Power required for machining
- 34. MRR – Material Removal Rate 34
- 35. Tolerance 35 . Engineering tolerance is the permissible limit or limits of variation in manufacturing
- 36. Surface Roughness / Finish 36 . Surface texture is one of the important factors that control friction and transfer layer formation during sliding.
- 37. Parts from EDM process 37
- 39. Parts from ECM process 39
- 40. Parts from Abrasive Water jet Machining 40
- 41. Parts from LASER Beam Machining 41
- 42. LIMITATIONS OF Un Conventional Machining 42 1. More expensive process 2. Low Material Removal Rate (MRR) 3. AJM, CHM , PAM and EBM are not commercially economical Process
- 43. ADVANTAGES of UCM 43 High Accuracy and surface finish in process Less Rejected pieces Increase productivity Tool material need not be harder than work piece material. Easy to machine harder and brittle materials There is no residual stresses in the machined material