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What are the common issues with swarf when machining sticky or long chipping materials like Aluminium?

Although Aluminium is usually seen as an easier material to machine (compared to, for instance, Stainless or Exotics), there are more general problems associated with machining “sticky” or “long chipping” materials like Aluminium.


You can expect to encounter various issues with these materials like unmanageable swarf, built up edge on your cutting tool and subsequently low tool life or poor surface finish. There are a few things to bear in mind when selecting the right tools that can help to combat this.



Tool selection

Although some advanced coatings are suitable for machining aluminium, the best option is usually an uncoated cutter with polished flutes. This is because when you’re machining any material a lot of heat is generated, but with aluminium this heat can cause the cut material to weld itself to the cutting edge.


Commonly this is referred to as a “built up edge”, which can make the tool blunt and prematurely causes you to have to regrind the tool or throw it away (even though the cutting edge is still intact!).


The best tools for cutting aluminium will also have a sharp cutting edge, high rake angle and a positive approach:


  • In turning applications, a smaller corner radius can be used for better surface finish without compromising on tool life.
  • In milling applications, tools with deep flute pockets and a high helix angle can be beneficial for dealing with swarf and avoiding tools clogging up with swarf (built-up edge).



 At Cutwel, we supply a wide range of Aluminium milling cutters (Alu Power HPC, Alu Power, A+ End Mills, CRX-S etc.) and turning inserts (AK H01 or PD1000 grade inserts).


For aluminium substrates with a high silicone content or abrasive properties, you should select a cutter with either a DLC (diamond like carbon) coating or a PCD tip (polycrystalline Diamond).



Getting the best out of your tool

It is important to select the correct cutting speed and feed when machining Aluminium. Commonly, a failure to push the tool as hard as it is designed to be pushed can be as bad as pushing the tool too hard. If your feed rate is too low, you can generate too much heat when cutting and increase the chance of getting a built-up edge on the tool. Conversely, if your feed rate is too high then you are likely to get clogged up flutes and cause the tool to break.



Because Aluminium cutters usually require higher cutting speeds than tools used on materials like Steel, it is important to use a balanced holder with the smallest run out value possible. Examples include a Hydraulic chuck, Shrink Fit chuck or a GSK/HP3 collet chuck. These can be run at much higher speeds than standard ER collet chucks.


If you have any questions or are looking for recommendations on the best set-up for your aluminium job, get in touch today by calling 01924 869615 or email sales@cutwel.net.