Why is it important to avoid very small primary clearance angles?

Avoiding very small primary clearance angles is crucial because such angles can lead to excessive wear on the milling cutter. When the primary clearance angle is too small, the geometry of the cutter does not provide enough space for the cutting edge to clear the material being machined effectively. This inadequate clearance can result in increased friction between the cutter and the workpiece, which accelerates wear on the cutting edge.

Excessive wear not only reduces the lifespan of the cutter but can also negatively impact the quality of the machined surface. It may lead to poor dimensional accuracy and surface roughness in the final product. Therefore, maintaining an appropriate primary clearance angle is essential for ensuring the longevity of the tool and the efficiency of the milling operation.