Feed per toothformula

Let me conclude simply by stating that excellent machinability of aluminium alloys is achieved by careful control of the alloy’s chemical composition and the parameters in all process steps.

Feed per toothchart

The most important aspect of milling with end mills is to run the tool at the proper RPM (revolutions per minute or spindle speed)  and IPM (inches per minute or feed rate).  We have broken these recommendations down into material categories so you can make better decisions with how to productively run your end mills.  Certain high performance mills have very specific running parameters relative to their material families.  We have listed these also as individual recommendations by coating family.  These documents are downloadable in pdf formats by clicking the links below.

In general, machining aluminium profiles is relatively inexpensive. I’m talking about processes such as sawing, turning, drilling, milling, threading and punching. One reason is that tool costs tend to be competitive due to low tool wear as a result of low specific cutting force. The cutting force in Al is only about a 1/3 of that with steel. In addition, the cutting speeds attainable with aluminium are much higher than for steel, thus leading to less-expensive machining compared to steel.

Feed per toothin inches

You can view this issue in the same way as a restaurant chef does when preparing a meal: The raw material matters. With aluminium, having the right material will improve machinability and thereby the final product.

feed per toothto mm/min calculator

The speeds and feeds formulas are in the bottom of the charts below.  If you follow these guidelines, you will have a much greater success rate in part programming, and you will be milling more efficiently.

That said, lead and bismuth are banned as alloying elements in some regions and applications. Where this is the case, good machinability alloys are 6061M and 6082M. These are special versions that are based on 6061 and 6082 with both tailored temper and composition for machinability.

We have created an excellent speeds and feeds calculator which incorporates these charts into the calculations.  It generates ranges of SFM or SMM and allows you to decide what SFM is appropriate.  It then automatically calculates the RPM.  Then it gives you a range for FPT and allows you to decide what is appropriate.  Then it automatically calculates the IPM or millimeters per minute (MMPM).  Try it out!  It is easy to understand.

One final point: Aluminium producers have traditionally added the low melting-point alloying elements lead (Pb) and bismuth (Bi) to 6xxx-series alloys to achieve good machinability. Examples are the 6042 and Hydro 6262 alloys.

Aluminium is a relatively easy material to machine. It is also relatively easy to excel in this work, as long as you understand the three factors that affect the machinability of the metal.

You can assess chip breakage with chip maps or chip counting. The first gives you a good overview of chip breakage at different cutting parameters, while the latter provides you with a more accurate measurement.

Feed per toothin mm

Feed per toothcalculator

Note:  These cutting feeds and speeds charts work with Accupro, Niagara, Data Flute, SPETool and all end mill brands.  We will have all of Harvey Tool speeds and feed charts loaded soon.

For 6xxx alloys, the general trend is that chip breakage increases with strength, both with harder alloys and tempers. However, this cannot always be translated to other alloy systems. For instance, it can be very difficult with some 7xxx alloys, despite their high strength, to get good chip breakage.

When choosing the right cutting parameters to run, most people focus on the speed  which relates to the machine RPM.  This is a mistake!  Focus on on the proper feed per tooth (FPT) first, and then adjust the speed.  Often when a part is programmed, and is being proven out for production, the programmer will choose conservative parameters and encounter chatter.  Chatter is nothing more that part vibration or noise, because the tool is not cutting properly.  Usually, the first response is to slow the RPM and the chatter will go away.  This often works, but this is unproductive.  What has just happened is that by reducing the speed and keeping the feed constant, the FPT has increased.  And most likely the FPT before was too low in the first place and that was what caused the chatter.

David has a Bachelor of Science degree in metallurgical engineering from Michigan Technological University as well as master's and doctorate degrees in metal science and engineering from The Pennsylvania State University.

Let me start with the two principal classifications of aluminium alloys: cast alloys and wrought alloys. Each classification is further divided into the categories heat treatable and non-heat-treatable. About 85% of aluminium is used for wrought products, such as rolled plate and foils, and extrusions. Here you can find large variations, with some alloys forming very small nice chips whereas others struggle with chip breakage.

The machinability of aluminium alloys can be difficult to predict, even for machinists. There are so many variables. One is the condition of the material, not to mention its physical properties – alloying elements, microstructure, hardness, yield strength, tensile strength, elongation, work hardening.