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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

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### A quick feeds and speeds course

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