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# A quick feeds and speeds course

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This slideshow is a quick course in speeds and feeds for cnc machinists

This slideshow is a quick course in speeds and feeds for cnc machinists

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### Transcript

• 1. G-Wizard Machinist’s Calculator
A Quick Feeds and Speeds Course
• 2. All Machinists Know the Basics
RPM = SFM * 4 / Cutter Diameter
Feed Rate = RPM * Chip Load * Teeth
Isn’t That Good Enough???
• 3. 4 Problems
Tables Are Worst Case Estimates
Chip Thinning
Compensating for Odd Shapes
Tool Rigidity
Classic Formulas Don’t Consider All the Variables…
• 4. #1 Tables are Worst Case Estimates
Only a Few Variables: Full Range of Tool Diameter, Depth of Cut, Width of Cut, Materials, etc.
No Interpolation
No Idea of Coolant or Other Conditions
Is Manufacturer Pushing Tool Life or MRR?
Have to Assume Worst Case
HSM Toolpaths can go 3-5x Faster
• 5. #2 Chip Thinning
Chip Thinning:
Simple formulas assume the red chip
The blue chip is reality.
You have to feed faster to get to the recommended chipload!
• 6. Irony: Babying the Cut is Bad For Cutter Life!
Think of the Cutter Edge Radius Versus the Chip Thickness:
Radius <= Chip Thickness: Shearing Cut
• Chip pushed under not over
• 7. Rubbing = Heat = Poor Tool Life
• 8. #3 Compensating for Odd Shapes
Not all cutters are nice and square in profile
Lead Angle Changes Feeds & Speeds
Ballnose Changes Feeds & Speeds
• 9. #4 Tool Deflection
All tools deflect, it’s about how much…
Roughing: > 0.001” = Onset of Chatter
Finishing: < 0.0002” for Accuracy and Finish
What’s the Impact of HP on Tooling & Machine?
• 10. Optimizing Feeds and Speeds is About Mastering More Variables…Hard to do by hand!
• 11. So We Use a Calculator!Let’s See How With G-Wizard