Categories

 

G-Wizard Calculator:
Fast, Easy, Reliable Feeds and Speeds

Subscribe

Join 100,000+ CNC'ers!  Get our latest blog posts delivered straight to your email inbox once a week for free. Plus, we’ll give you access to some great CNC reference materials including:

  • Our Big List of over 200 CNC Tips and Techniques
  • Our Free GCode Programming Basics Course
  • And more!

 

GCode is Complicated
G-Wizard Makes it Easy

When is Cutting Aluminum at 1000 SFM Just Like Cutting at 300 SFM?

Feb 19, 2016   //   by Bob Warfield   //   Blog, FeedsSpeeds, GCode, Software, Techniques  //  2 Comments

Strange question, right?  Almost nonsensical.  Surface Speeds are surface speeds, and a difference of 700 SFM has got to result in a difference to the cutter–probably a BIG difference.  Yet, paradoxically, there is reason to believe, backed by science, that 1000 SFM really can be just like 300 SFM in some cases during High Speed Machining.

This is just one of the interesting factoids uncovered in the High Speed Machining chapter of our Free Feeds and Speeds Tutorial.  If you’ve never thumbed through that resource, you’re missing out on a wealth of free knowledge that can help you to be a Better CNC’er.  It’s completely free and each article is a bite-sized nugget of goodness that will tell you all about some aspect of Feeds and Speeds or some other specialized machining condition such as Conventional vs Climb Milling and when each should be used.

I bring all of this up because I just spent all morning the other day revising the High Speed Machining and the Toolpath chapters.  I do this whenever I discover new information relevant to one of our existing in-depth Cookbook’s.  Our Blog Posts have a little shorter and more “newsworthy” sort of lifespan.  But the Cookbooks are sacrosanct–they’re Evergreen Content that we want to keep up to date so they’re the best possible source of information on the Internet for the topics they cover, and they’re always free.

So, if you’re wondering about that aluminum, here’s the scoop:

SurfaceSpeedVsHeatHSM

Temperatures actually come down as cutting speed (surface speed and spindle rpm) increases…

This amazing chart is from Dr Herbert Schulz’s, “History of High Speed Machining.”

The dotted lines represent temperatures at various surface speeds. Note that all of the materials go steadily up and then eventually start dipping back down again as surface speed increases. Somehow, temperatures decrease beyond a certain spindle rpm!

This chart is in meters/minute, so multiply the values by about 3 to get to SFM. For aluminum, we have a pretty good dip by the time we’re hitting 1000 SFM, for example. In fact, it’s temperature is more equivalent to less than 300 SFM on the other side of the aluminum curve–that’s nothing for aluminum. Heck, if we have a fast enough spindle, there’s even room to run HSS faster and get lower temperatures (you’ll note various cutter materials critical temperatures are also marked off–stay below the line for your cutter!).

Steel and cast iron taper down more gently than aluminum, but the effect is still alive and well. Yes Virginia, there surely is some strange behavior when you start in with that HSM stuff!

The same research showed that cutting forces also come down, and that’s at least one reason why the temperatures drop, and why for HSM machining in the right rpm ranges, you can achieve high MRR’s with lower cutting forces.

For all this, and more, check out:

  • High Speed Machining:  Tool Engagement Angle, Trochoidal Milling, Peeling, and all that Jazz.  You can even learn how much to slow down in corners if you can’t use HSM.
  • Toolpath Considerations:  Quick, is it better to plunge, ramp, or helix into a pocket?  All that and much more in terms of telling you how to give your CAM software the very best option choices for your CNC job.
 

Like what you read on CNCCookbook?

Join 100,000+ CNC'ers!  Get our latest blog posts delivered straight to your email inbox once a week for free. Plus, we’ll give you access to some great CNC reference materials including:

  • Our Big List of over 200 CNC Tips and Techniques
  • Our Free GCode Programming Basics Course
  • And more!

Just enter your name and email address below:

Full Name
Email *
100% Privacy: We will never Spam you!

When is Cutting Aluminum at 1000 SFM Just Like Cutting at 300 SFM?
Rate this post

2 Comments

  • Titanium is non-ferrous 😉

    • ROFL, you got that right, Brad!

      There are a lot of things that make Titanium tough. One that’s germane to this discussion is that it doesn’t conduct heat well. Titanium exhaust valves for racers typically are filled with sodium to help carry the heat away. When machining, we have to work extra hard to manage that stubborn heat. Making darned sure as much as possible leaves with the chips is critical.

Leave a comment

 

Do you want to be a better CNC'er in 37 Seconds?

Get Better Tool Life, Surface Finish, and Material Removal Rates Fast.

It's that easy. You can install and get results in a matter of minutes.

 

Start Now, It's Free!

Home

Software

  GW Calculator

  GW Editor

  Gearotic

  Conversational

  Deals and Steals

CNC Blog

  Software

  Techniques

  Beginner

  Cool

  Projects

 

Cookbooks

     Feeds and Speeds

     G-Code Tutorial

     CNC Machining & Manufacturing

     DIY CNC Cookbook

     CNC Dictionary

CNC Projects

Resources

     Machinist's Search

     Videos

     Online Groups

     Individuals

     Reference Data

     Books

     CNC Dictionary

     Suppliers

     Tool Brands

Workshop

     Hall of Fame

     Organization: Soon!

 

About

     Customers

     Partners

     Our History

     Privacy Policy

 
All material © 2016, CNCCookbook, Inc.