What is the difference between cyclic light reaction and non-cyclic light reaction?

During down-cut milling,the table feeds the workpiece in the same direction as the cutter rotation.As the cutter contacts the workpiece, chip thickness is maximum and gradually reduces to nil as the cutter exits the material.                                                             2.During up-cut milling,the table feeds the workpiece in the opposite direction to the cutter rotation, this results in three distinct phases of chip formation, i) the cutting edge slides over the surface, ii) it starts to crush the surface material and iii) the cutting edge gains a purchase and chip formation begins, to a maximum thickness as the tooth leaves the workpiece.