Factors affecting tool life in machining processes
- 1. Factors Affecting Tool Life In Machining Processes
- 2. Factors Affecting Tool Life In Machining Processes What are these??
- 3. Factors Affecting Tool Life In Machining Processes ME 572 Analysis of Manufacturing Processes Mohammad AlJuhani
- 4. Factors Affecting Tool Life In Machining Processes Introduction Tool Life and Machinability Tool Damage Causes of tool damage Factors Affecting Tool Life in Machining Processes
- 5. Factors Affecting Tool Life In Machining Processes • Cutting tool life is important consideration in metal cutting processes. • In machining operations, cutting conditions such as tool angles, cutting speeds and feed rates are usually selected to give an economical tool life. • Conditions giving a short tool life are uneconomical because tool grinding and tool replacement costs are high. • Factors affecting tool life should be carefully monitored to minimize their consequences.
- 6. Factors Affecting Tool Life In Machining Processes • A tool that doesn’t perform the desired function can be declared as failed, or reached the end of its useful life. • At this point of time, the tool is not necessarily unable to cut the workpiece but is merely unsatisfactory (may not give the desired surface finish or dimensional tolerances) for the purpose required • The tool life is defined as the length of cutting time that the tool can be used. Tool Life and Machinability
- 7. Factors Affecting Tool Life In Machining Processes • Tool damage can be classified into two groups, wear and fracture by means of its scale and how it progresses. • Wear is loss of material on an asperity or micro-contact, or smaller scale, down to molecular or atomic removal mechanisms. It usually progresses continuously. • There are two main types of tool wear • Flank wear • Crater wear • Fracture, on the other hand, is damage at a larger scale than wear and it occurs suddenly. Tool Damage
- 8. Factors Affecting Tool Life In Machining Processes Tool damage. Flank wear vs. cutting time
- 9. Factors Affecting Tool Life In Machining Processes Mechanical Damage Thermal Damage Adhesion Causes of tool damage
- 10. Factors Affecting Tool Life In Machining Processes Mechanical Damage Mechanical Damage FractureChippingAbrasion Fatigue It is independent of temperature. Causes of tool damage
- 11. Factors Affecting Tool Life In Machining Processes Causes of tool damage Mechanical Damage
- 12. Factors Affecting Tool Life In Machining Processes Thermal Damage Plastic deformation DiffusionChemical reaction It increases drastically with increasing temperature Causes of tool damage
- 13. Factors Affecting Tool Life In Machining Processes Causes of tool damage
- 14. Factors Affecting Tool Life In Machining Processes Causes of tool damage
- 15. Factors Affecting Tool Life In Machining Processes Occurs when work or chip material welds to the tool surface. Adhesion Damage Causes of tool damage
- 16. Factors Affecting Tool Life In Machining Processes Causes of tool damage
- 17. Factors Affecting Tool Life In Machining Processes Factors Affecting Tool Life Cutting Tool Geometry Cutting Tool Material Cutting Tool Characteristic s Cutting Conditions Workpiece Material. Cutting Fluid
- 18. Geometry of cutting tool varies with Type of operation being performed, Surface finish requirements. Power and speed of machine Workpiece material, Factors Affecting Tool Life In Machining Processes Cutting Tool Geometry
- 19. Cutting tool geometry is directly affects Machined surface quality. Productivity of machining. Chip control. Magnitude and direction of the cutting forces Tool life. Distribution of the thermal energy Temperature distribution in the cutting wedge Factors Affecting Tool Life In Machining Processes Cutting Tool Geometry
- 20. Factors Affecting Tool Life In Machining Processes Cutting Tool Geometry
- 21. Factors Affecting Tool Life In Machining Processes Rake angle Rake angles are three types, positive, zero and negative. For ductile materials, the rake inclination is a positive angle Since their shearing is low. For brittle materials, the rake inclination is a negative angle. The advantages of increasing rake angle • Reduces the horsepower consumption. • The cutting force and tool-chip contact temperature change in approximately the same way. The disadvantages of increasing rake angle • The strength of the cutting wedge decreases when the rake angle increases. • The region of the maximum contact temperature at the tool-chip interface shifts toward the cutting edge. Cutting Tool Geometry
- 22. Factors Affecting Tool Life In Machining Processes Flank angle The flank angle affects the performance of the cutting tool mainly by decreasing the rubbing between the tool surface and workpiece surface. With increasing the flank angle the following advantages are obtained: • Cutting edge radius decreases which leads to decrease in the frictional and deformation components of the flank force. • The strength of the region adjacent to the cutting edge decreases. • Heat dissipates through the tool decreases. Cutting Tool Geometry
- 23. Factors Affecting Tool Life In Machining Processes Nose Radius Nose radius is very critical part of the cutting edge. If the radius is made of sharp angle, the produced finished surface will be rough and tool life will be short. A large nose radius benefits • Better surface finish. • Faster feed rate. • Stronger tool. • Allow faster cutting speed However, large radii have negative sequences such as tool chatter. Cutting Tool Geometry
- 24. Factors Affecting Tool Life In Machining Processes Cutting Tool Material Factorsaffectingselection cuttingtoolmaterial The cutting operation involved Workpiece material Production requirements Surface finish and accuracy requirements. Machine to be used
- 25. Factors Affecting Tool Life In Machining Processes Cutting Tool Material Major qualities required in a cutting tool Resistance to heat (hot hardness) Resistance to mechanical impact thermal shock. Resistance to wear (hardness) Resistance to fracture (toughness) Chemical stability to the workpiece material
- 26. Factors Affecting Tool Life In Machining Processes Cutting Tool Material
- 27. Factors Affecting Tool Life In Machining Processes Today, 50% of HSS, 85% of carbide and 40% of super-hard tools used in industry are coated Cutting Tool Material Cutting Tool Coating Improve wear resistance Reduce thermal conductivity. Reduce frictional contact.
- 28. Factors Affecting Tool Life In Machining Processes Cutting Tool Material Uncoated cutting tool Coated cutting tool
- 29. Factors Affecting Tool Life In Machining Processes CuttingToolCharacteristics Tostandagainsthighstress Pressure resistance. Bending strength. Edge strength. Inner bonding strength. High temperature strength. Small propensity to diffusion and adhesion (Chemically stable). Abrasion resistance. Reproducible wear behavior. Cutting Tool Characteristics
- 30. Factors Affecting Tool Life In Machining Processes Depth of cut Feed rate Cutting Speed Cutting Conditions
- 31. Factors Affecting Tool Life In Machining Processes Cutting Conditions Depth of cut Feed rate Cutting Speed
- 32. Factors Affecting Tool Life In Machining Processes Cutting Conditions Depth of cut Feed rate Cutting Speed
- 33. Factors Affecting Tool Life In Machining Processes Depth of cut Feed rate Cutting Speed Cutting Conditions
- 34. Factors Affecting Tool Life In Machining Processes Cutting Conditions Depth of cut Feed rate Cutting Speed
- 35. Factors Affecting Tool Life In Machining Processes Depth of cut has least effect upon tool life, so the heaviest (10 times the feed rate) possible depth of cut should always be used. Depth of cut is limited by • Amount of metal to be machined from the workpiece, • Power available on machine tool, • Rigidity of the work piece and cutting tool • Rigidity of the setup. • Workpiece configuration • Insert size & thickness Cutting Conditions Depth of cut Feed rate Cutting Speed
- 36. Factors Affecting Tool Life In Machining Processes Cutting Conditions Depth of cut Feed rate Cutting Speed
- 37. Factors Affecting Tool Life In Machining Processes Machinability of workpiece criteria Tool life Surface roughness Surface integrity Magnitude of cutting forces Energy (power) consumption Workpiece Material.
- 38. Factors Affecting Tool Life In Machining Processes Factors determine conditions of the work material Microstructure. Grain size. Heat treatment. Chemical composition. Fabrication Yield and tensile strength. Hardness Workpiece Material.
- 39. Factors Affecting Tool Life In Machining Processes Main Cutting Fluid Functions Lubrication effect Cooling effect Removing chips away from the cutting zone Cutting Fluid
- 40. Factors Affecting Tool Life In Machining Processes Otherfunctionsofcuttingfluids Reduction of cutting forces/ energy consumptions. Improvement of surface finish and dimensional accuracy. Extend tool life. Facilitate chip removal. Corrosion prevention on workpiece and machines. Lowering workpiece temperature. Lubrication of machine tool sliding guides Cutting Fluid
- 41. Factors Affecting Tool Life In Machining Processes Cuttingfluidsproperties Good lubricating properties High cooling capacity Low viscosity to provide free flow of cutting fluid. Chemically stable. Non-corrosive. High flash point to reduce fire risks. Allergy free. Less evaporative. Low cost. Cutting Fluid
- 42. Cutting Fluids Selection Type of machining processes. Type of machined workpiece material. Type of cutting tool material. Factors Affecting Tool Life In Machining Processes Cutting Fluid
- 43. Factors Affecting Tool Life In Machining Processes Cutting Fluid CuttingFluidEffects Environmental Biodegradability Life cycle assessment Bioaccumulability and biomagnifications Energy saving and fuel economy Renewability Health Respiratory problems. Dermatological problems
- 44. Factors Affecting Tool Life In Machining Processes Environmental machining Dry cutting Minimum quantity lubricant Vegetable based cutting fluids Cutting Fluid
- 45. Factors Affecting Tool Life In Machining Processes
- 46. Factors Affecting Tool Life In Machining Processes
- 47. Factors Affecting Tool Life In Machining Processes Cutting Tool Geometry