How Chip Evacuation in Machining is Like Cutting the Lawn

Chip evacuation during milling processes impacts efficiency and quality and single flute end mills featuring a large chip room allow for better chip evacuation yielding a better cut, longer tool life and making high feed rates possible.

Whenever a machinist is trying to improve the quality of a part or decrease cycle time, often the focus is on the program. This is the obvious and natural course of action to take but often a change in cutting tools can also have a dramatic effect. The old adage of having the right tools for the job absolutely applies in machining. Dramatically reducing cycle times particularly holds true when machining non-ferrous metals such as aluminum with single flute cutters.

For over 25 years, DATRON has produced high speed machining systems. They also have produced their own line of cutting tools that leverage the high range (up to 60,000 rpm) of spindle speed they offer. For example, using conventional cutting tools designed for machining steel often has mixed results when machining in aluminum. The reason for this varies but the key factor in obtaining a better quality of cut and improved feed rates can be achieved with improved chip evacuation.

Through my ten plus years of teaching and training on DATRON high-speed machining systems, I learned a very simple analogy about chip evacuation. If you have ever cut your lawn and the grass clippings have clogged your lawnmowers exhaust opening, did you notice what happened to the quality of cut of your grass? Terrible right. The grass seems more torn that cut, there are uneven lengths and you likely had to slow your pace way down. If the grass clippings start to get caught up inside, this starts to interfere with the new grass being cut, the grass clippings keep getting recut almost into a paste. This creates a real mess that could even stall your lawnmower. This is very similar to what happens in machining, if you do not properly evacuate the chips. The only difference is instead of stalling the lawnmower, you likely will break the cutting tool. Therefore your goal for optimum speed or feed rate is to get the chip clear of the cutting tool.

One distinct advantage of using a high speed spindle means, you do not necessarily need to use a multi-fluted end mill. The rotation speed of the tool is so fast, often just two flutes or even a single flute tool will suffice. Using just a single fluted tool means there is a lot of open space or clearance around the back side of the tool.

Chip evacuation in CNC machining facilitates high feed rates, better cutting quality and reduced tool breakage.
Chip evacuation is facilitated by a large “chip room” (open space) .

This space provides a much larger opening for the chip to evacuate sending a rooster tail effect of chips away from your part (see the video above). The lawnmower with a very small opening for the grass to exhaust is like using a four fluted tool. The larger the opening, the better the grass clippings or aluminum chips will evacuate. Getting the already machined chips out of the path of your cutting edge will have a significant improvement on your cutting quality and allows you to walk faster, I mean machine faster for a shorter overall cycle time.

Machining your parts better and more quickly should give you a lot more time to do other things, including cutting the lawn.

Bill King
President of Datron Dynamics