Without any corners, round insertion provides the strongest cutting edges available in indexable carbide blades. Strength comes in handy when you’re operating on a very heavy cut, or if you try a rough cut under unstable conditions. When using long tool cutting, circular insertion makes it easier to deflect and flutter, increasing speed and feed rate, reducing the risk of insertion.
The cuts are also more effective. A typical 90-degree cutting tool, most of the tool pressure is radial, causing high deflection and increased likelihood of vibration or breakage. The circular cutting edge spreads the force more evenly, and the greater proportion of the tool pressure guide axial direction. This is also desirable when using a longer length tool, since reduced radial pressure reduces deflection.
But pay attention to this when you use a horizontal machining center. An increase in axial pressure may result in the bending of the workpiece, usually on a pedestal or corner plate, rather than as a solid base for a vertical machining center. On the HMC, this bending can cause microchips to be inserted into the tiny vibration of flex. Cutting tool life and cutting tool breakage are more likely. To reduce or eliminate this problem, you can try a positive axial rake cutter, which minimizes the downward thrust to the workpiece.
Low – horsepower metal cutting
In the right way, round inserts can produce impressive material removal rates without an impressive horsepower. The strength of the round insertion can make it impossible to use the 90 degree cutting tool speed, even the lightest machine can be violently roughened. The key point to understand with circular insertion is that a heavier cutting depth leads to higher chip thickness, which increases the power consumption. (see figure 1). Through light cutting – 0.025 to 0.50 inches deep cutting – a typical circular cutting tools can be at a rate of around 0.040 inches per tooth to provide feed, in some cases, each teeth up to 0.060 inches. In contrast, most of the parallelogram or square inserts limit in 0.010 to 0.012 ipt.