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CNC Machining and Defects Analysis_Troubleshooting
- 1. Machining Defects Analysisand Troubleshooting • Chatter Marks | Built-Up Edge | Step Marks | Chip Formation | Dent in Machining
- 2. Introduction • Objective: • Understanddefects, analyze causes, enable troubleshooting • Scope: • Turning, Milling, Drilling • Focus on surface finish, tool wear, process stability
- 3. Classification of MachiningDefects • Surface Defects: Chatter, dents, step marks • Tool-Related Defects: Built-up edge, excessive wear • Chip Formation Defects: Irregular chips, poor evacuation
- 4. Chatter Marks • Definition:Vibrations causing wavy surface finish • Causes: • Improper spindle speed or feed • Tool overhang or instability • Machine resonance • Identification: Wavy, repetitive pattern • Prevention: • Optimize speed/feed • Use rigid tooling • Dampen vibrations
- 5. Built-Up Edge (BUE) •Definition: Material sticks to cutting edge causing poor finish • Causes: • - Low cutting speed • - High friction • - Inadequate coolant • Effects: Poor finish, dimensional inaccuracy, tool damage • Prevention: • - Increase cutting speed • - Use proper coolant • - Select suitable tool material
- 6. Step Marks • Definition:Uneven steps on machined surface • Causes: • - Incorrect feed rate • - Tool deflection • - Improper tool path • Detection: Visual or tactile • Prevention: • - Adjust feed and step-over • - Ensure rigid setup • - Regular tool inspection
- 7. Chip Formation Issues •Definition: Poor chip morphology • Causes: • - Wrong cutting speed/feed • - Incorrect tool geometry • - Poor lubrication • Types: Continuous, discontinuous, built-up, tubular • Prevention: • - Optimize speed/feed • - Modify tool geometry • - Use appropriate cutting fluid
- 8. Dents in Machining •Definition: Indentations on workpiece surface • Causes: • - Tool impact or improper entry • - Hard inclusions in material • - Vibration or machine jerk • Effects: Surface damage, functional failure • Prevention: • - Reduce tool entry speed • - Inspect material for hard spots • - Maintain machine stability
- 9. Troubleshooting Summary Table •| Chatter | Machine vibrations, overhang | Optimize speed/feed, rigid setup | • | BUE | Low speed, friction | Increase speed, proper coolant |
- 10. Troubleshooting Summary Table •| Step Marks | Feed variation, tool deflection | Adjust feed, rigid setup | • | Chip Formation | Wrong geometry/speed | Optimize cutting, tool design |
- 11. Troubleshooting Summary Table •| Dents | Tool impact, material | Reduce entry speed, check material |
- 12. Case Study /Practical Example • Example: Chatter mark in turning steel shaft • Cause analysis & corrective action
- 13. Key Takeaways • Defectsreduce productivity and quality • Most defects are preventable • Continuous monitoring & corrective actions improve efficiency