Views: 76 Author: Site Editor Publish Time: 2022-05-20 Origin: Site
When a tungsten steel milling cutter performs a milling process, the workpiece can be fed in the direction of rotation with or relative to the tool, which affects the starting and finishing characteristics of the cut.
When a tungsten milling cutter is used for down milling (also called isotropic milling), the workpiece is fed in the same direction as the tungsten milling cutter rotation in the cutting area. The chip thickness decreases gradually from the beginning until the end of the cut is zero in peripheral milling; in reverse milling (also called reverse milling), the feed direction of the workpiece is just opposite to the rotating direction of the milling cutter in the cutting area. The chip thickness starts at zero and then gradually increases with the cutting process.
In reverse milling, the tungsten carbide milling cutter insert starts cutting from zero chip thickness, which generates a high cutting force that pushes the tungsten carbide milling cutter and the workpiece away from each other. When the tungsten milling cutter insert is forced into the cut, it usually comes into contact with the machined hardened surface caused by the insert being cut, while friction and high temperatures produce friction and polishing effects. The cutting force also lifts the workpiece off the table more easily.
When milling downstream, the tungsten carbide milling cutter insert starts cutting at the maximum chip thickness. This avoids the polishing effect by reducing the heat and the tendency to harden the machining. The application of the maximum chip thickness is very beneficial and the cutting force makes it easier to push the workpiece into the tungsten milling cutter to allow the tungsten milling cutter insert to perform the cutting action.
When milling tungsten carbide cutters, chips are sometimes glued or welded to the cutting edge and collect around the start of the next cutting edge. When milling backwards, chips are more likely to be trapped or wedged between the insert and the workpiece, which can cause the insert to break. When milling downstream, the same chips are split in two, thus not damaging the cutting edge.
Regardless of the requirements of the machine, fixture and workpiece, paramilling is the preferred method.
Paramilling places special demands on the process because of the ease with which cutting forces can push the insert forward while keeping the workpiece underneath. This requires the machine tool to handle the table feed requirements by eliminating tooth clearance. If the tool is pushed into the workpiece, the feed will increase irregularly, resulting in excessive chip thickness and can cause chipping. Reverse milling should be selected for such applications. Also, if there is a large variation in the machining allowance, it is more advantageous to choose reverse milling. Proper clamping of the workpiece requires a suitable fixture, and for the same operation the correct tool size is required. However, for vibration trends, the direction of the cutting force is more important.