Mill Feeds and Speeds - solve RPM and Feedrate
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- čas přidán 20. 08. 2024
- In this video you will learn the simple equations for solving spindle speed and feed rate for a manual vertical milling machine.
The textbook I use is, "Technology of Machine Tools" - 7th edition. I am not sponsored by or affiliated with the publisher but I use this book for most of my machining curiosities and I use it when teaching machinist apprentices their theory lessons.
If there is information you would like me to put together in a video please feel free to contact me. Thanks Santo for your request for this content.
Thank you once again for all your support. Have fun making chips!
In addition, the teaching platform I use is from Lightboard Depot. Once again I am not sponsored by or affiliated with them but this teaching tools is fantastic.
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Should the feed rate for the lathe at 12mins in not be in inches per revolution, instead of inches per minute?
For clarification, the formula for Feedrate is RPM x Feed per Tooth x Number of cutting Teeth.
In the video I just refer to Feed per Tooth as Feed.
The solved 88ipm is the Feedrate in inches per minute.
The correct (simplified) formula is RPM=(SFMx3.82)/Diameter.
People who use 4 instead of 3.82 are the "looks good from my house" guys. To simplify the real formula, you divide 12 (feet) by Pi (used in the circumference calculation). 12/Pi = 3.8197, which you would then round to 3.82, not 4. The book I have from college uses 4 as well, and it drives me crazy because the Machinery's Handbook uses the real formula. In machining, you need to be as accurate as possible, especially with harder materials. Please stop saying 4 is close enough.
***This is not an attack on you, it's an attack on the people who wrote the book that gave you the information.***
Other than that, this is great advice.
Hi Adam
Thank you for video
Is cutting speed for metric and inch drill same or different? when you use formula N=Vc *318/D and N=Vc*3.82/D?
Also Is cutting speed chart for drill and lathe also mill same?
Hello again @silkroad9188. Cutting speed for imperial is in feet per minute and for metric is in meters per minute.
Simplified inch formula:
4xcutting speed/diameter of the tool (milling machine)
for metric
320xcutting speed/diameter of the tool (milling machine)
320 is the standard and doesn't change.
The non-simplified formula for imperial cutting speeds is:
12 x cutting speed / pi x diameter of the tool
I usually only use this formula when solving spindle speeds for a CNC mill as the spindle speeds solved can actually be used where on a manual mill, only approximate speeds can be reached.
Once again, I hope this helps!
Is there a formula to scaled-down feed speed? If my free rate is 7.353.6 RPMs but my machine max speed is 3,000. Is there an equation to scale the speed?
I'm not sure exactly what you're asking. What is the RPM that you calculated? And what is the maximum RPM that your machine can run? Because if you're asking if there's a way to calculate RPM based on your maximum spindle capabilities, then yes I can help you with that.
Cross multiply, then divide. Ratios are pretty simple
@adamtaylor999 yes I'd like to know this!
James