What problems should be paid attention to in the process of die milling?

Milling is a process in which the CNC milling machine performs complex rotation, and the high-speed rotating milling cutter feeds on a fixed blank to cut out the required shapes and features. Traditional milling is mostly used to mill simple shape features such as contours and grooves, while CNC milling machines can cut complex shapes and features, and are mostly used to manufacture molds, fixtures, thin-walled complex surfaces, blades and so on. When selecting the content of NC milling, we should give full play to the advantages and key functions of NC milling machine.

Problems needing attention in die milling;

First, the choice of tool materials.

Reasonable tool materials with good cutting performance should be selected according to the characteristics of die raw materials. For example, high-speed steel and universal cemented carbide tools with good hardness at high temperature should be selected for thermoforming dies used at high temperature because of their high hardness. When choosing tools made of titanium alloy and stainless steel mold materials, cemented carbide tools should be avoided.

Second, the choice of cutting methods

When determining the die-cutting process, we should consider adapting to the requirements of high-speed cutting and try to choose positive milling. In forward milling, the chip thickness is the largest when the tool just cuts into the workpiece, and then decreases gradually. The reverse milling is just the opposite, so the friction between the tool and the workpiece is greater, the heat generated on the blade is more than that of the forward milling, and the radial force is greatly increased, thus reducing the life of the tool.

Third, the choice of feeding methods

When cutting the mold, it is necessary to avoid direct vertical downward feed, and diagonal feed or spiral feed is more suitable for high-speed cutting of the mold cavity. The diagonal feed mode is to gradually increase the axial depth to the set axial depth, the milling force is gradually increased, and the impact on the cutter and spindle is small, which can obviously reduce the phenomenon of edge collapse. The spiral feed starts from the top of the workpiece and spirals downward into the workpiece. Because it is a continuous cutting mode, it is easy to ensure accuracy and there is no sudden change in speed, so it can be carried out at a higher speed.

Fourth, the choice of cutting methods

In high-speed cutting, higher requirements are put forward for the setting of tool path. In high-speed cutting, because the cutting speed and feed speed are very fast, if the tool path is unreasonable, it is very easy to cause the sudden change of cutting load in the cutting process, which will bring impact damage to the workpiece and even the tool equipment, which is much more serious than ordinary cutting. Therefore, in high-speed cutting, we should choose the corresponding tool path according to different die materials and shapes, and we should not blindly pursue high speed and high efficiency.

V. Selection of cutting parameters

The choice of cutting speed is mainly limited by tool durability, which in turn depends on tool wear. The values of cutting parameters, such as cutting speed, feed rate and feed rate, should be appropriately reduced compared with the traditional turning of ordinary steel.

Six, the choice of cutting oil

When cutting molds such as cast iron and high manganese steel, cutting oil with strong antirust function should be selected. When cast iron and bronze are brittle materials, chips are often formed during cutting, which are easy to flow around with cutting oil and between machine tool rails, causing parts damage. Cutting oil with good cooling and cleaning performance can be used and filtered. When cutting alloy steel and titanium alloy, if the cutting amount is low and there is no requirement for surface roughness, such as broaching and thread cutting, extreme pressure cutting oil with excellent extreme pressure performance can be selected as the main additive.