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BREAKING IT DOWN CHIP BY CHIP
FIVE THINGS TO KNOW ABOUT CHIP FORMATION IN MACHINING
Whether examining how tool selection is impacting chips, how coolant plays a role in chip evacuation or looking at the size
and shape of chips, chip formation says a lot about the application being run. Knowing what different chip details indicate allows machinists to better manage chip formation, make adjustments and prevent tool failure. Because when it comes down to it, better chip formation means a more successful application.
SHAPE & SIZE
When looking at chip formation, a key indicator of a good chip is the shape. The preferred outcome for any application is chips shaped as sixes and nines or a single conical shape. These small, manageable chips are essential for efficient, predictable drilling. Nevertheless, it is important to be aware of what chips in other shapes and sizes can indicate. For example, a straight, flat chip is a result of elasticity. If the chip is a continuous ribbon, then there are likely many adjustments that need to be made in order to achieve ideal chips.
The size of the chips impacts evacuation as well. There are two major factors that impact the size of chips in drilling tools: chip breakers, also known as chip splitters, and lip geometry. With chip breakers, the width of the chip is thinned to allow for easier evacuation; the wider the chip the easier it is to get it to roll onto itself and break. Lip geometry acts as a mechanical chip breaker to fracture a chip by curling the chip on top of itself or by impacting the chip forming with the backside of the lip radius. Although harder materials will curl a chip on top of itself to create chip fracture, gummier materials often skip over the lip radius and only fracture after impacting the back of the lip radius. Still, the purpose of the combined chip breakers and positive lip geometry is to break off the chip so that it is narrow enough to easily evacuate.
Chip fracturing can also occur naturally due to the velocity differential between the outside and inside of a chip, which creates a cone-shaped chip that curls on itself and fractures. Because larger diameter inserts have a higher velocity differential than smaller diameter inserts, it is easier to fracture chips i.e., the larger the chip breaker
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CNC WESTJune/July 2022
Provided by Allied Machine & Engineering