CNC: Milling with an end mill – how exactly is the chip formed and broken ?
Here’s a beautiful slow motion video of an end mill cutting steel.
Video source: Taegutec
You can see the cutting action clearly, including the chip formation. You can see each chip curling and then breaking.
Pic. source: Taegutec
In each revolution of the end mill, an insert comes in contact with the part at location 1 and loses contact at location 2. When the insert comes in contact with the part there is a sudden shock load on it, and this is where its toughness is useful.
The video is an example of down milling. The chip thickness is highest when the insert contacts the part, and reduces gradually to zero.
