Difference between forward milling and reverse milling

What are forward milling and reverse milling?

Viewed along the feed direction of the cutter, if the workpiece is located on the right side of the feed direction of the milling cutter, the feed direction is called clockwise. Conversely, when the workpiece is located on the left side of the milling cutter feed direction, the feed direction is defined as counterclockwise. If the rotation direction of the milling cutter is the same as the feed direction of the workpiece, it is called forward milling, and the rotation direction of the milling cutter is opposite to the feed direction of the workpiece, it is called reverse milling.

2、 Tool forward milling and reverse milling

1. During reverse milling, the cutting thickness changes from thin to thick, and the cutter teeth cut from the machined surface, which is beneficial to the use of milling cutter. During reverse milling, when the cutter teeth of the milling cutter contact the workpiece, they cannot cut into the metal layer immediately, but slide on the workpiece surface for a short distance. In the sliding process, due to strong friction, a large amount of heat will be generated. At the same time, it is easy to form a hardened layer on the surface to be machined, which reduces the durability of the cutter, affects the surface finish of the workpiece and brings adverse effects to cutting. In addition, during reverse milling, the cutter teeth are cut from bottom to top.

2. During forward milling, when the cutter teeth start to contact the workpiece, the cutting thickness is large, and the cutting starts from the hard layer on the surface. The impact load of the cutter teeth is large, and the milling cutter becomes blunt faster, but there is no slip phenomenon during the cutting process.

The power consumption of forward milling is smaller than that of reverse milling. Under the same cutting conditions, the power consumption of forward milling is 5% ~ 15% lower. At the same time, forward milling is also more conducive to chip removal. Generally, the forward milling method should be used as far as possible to improve the surface finish of the machined parts and improve the effective processing of the machining performance of NC tools. Ensure dimensional accuracy. However, when there is hard layer, slag accumulation and obvious unevenness on the cutting surface, such as processing forging blank, the reverse milling method shall be adopted.