Inches per tooth feed rate (IPT) is the distance the cutter moves per tooth engagement with the material. It’s an essential factor in determining how much material is removed per cutting pass. The "Chip Thinning Adjustment" is a correction applied to the IPT when using certain cutting techniques, primarily during radial engagements (like milling) that are less than 50% of the tool diameter. This adjustment helps optimize cutting performance and tool life by accounting for variations in the actual chip load, or thickness, per tooth.
Inches per Tooth Feed Rate (Chip Thinning Adjustment) Formula |
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| \( IPT \;=\; \dfrac{ CT \cdot d }{ 2 \cdot \sqrt{ ( d \cdot RDOC ) - RDOC^2 } }\) | ||
| Symbol | English | Metric |
| \( IPT_{adj} \) = Inches per Tooth Chip Thinning Adjustment | \(in\) | \(mm\) |
| \( CT \) = Chip Thickness | \(in\) | \(mm\) |
| \( RDOC \) = Radial Depth of Cut | \(in\) | \(mm\) |
| \( d \) = Tool Diameter | \(in\) | \(mm\) |
Why Chip Thinning Adjustment is Needed
When the radial depth of cut (width of cut) is small, less than half of the cutter diameter, the actual thickness of the chip is less than the calculated IPT. Without adjusting for this, the feed rate may be set too low, which can reduce productivity and potentially lead to tool rubbing rather than cutting.
