How to open cross flutes on tungsten steel milling cutter?

If there is no circular groove on the front of the end face of the four-blade tungsten steel milling cutter, you need to use the fillet of the grinding wheel or use a grinding wheel cutting machine to re-open the cross groove in the direction of the cross spiral groove of the milling cutter, with a depth of about 1 to 2 mm (too deep is easy to Cracked, too shallow to easily grind out the secondary rear corner). When grooving, be careful not to touch the side of the grinding wheel with the other cutting edge below (Note: This cross groove has a chip removal effect. If it is not opened, the inclination angle of the edge recessed in the middle should be increased)