There are many kinds of milling cutters, so how should we choose milling cutters in machining?
Compared with a carbide milling cutter, the white steel milling cutter is softer. High-speed steel cutter is cheap and has good toughness, but its strength is not high. It is easy to make the cutter, and its wear resistance is relatively poor. The high-speed steel milling cutter has a thermal hardness of about 600 degrees and a hardness of about 65hrc. It is obvious that when using white steel to mill hard materials if the coolant is not in place, it is easy to burn the cutter. This is one of the reasons for the low thermal hardness.
Hard alloy milling cutter has a good thermal hardness, wear resistance, but poor impact resistance. If you drop the blade casually, it will be broken. Hard alloy is made by powder metallurgy, with the hardness of about 90hra and thermal property of about 900-1000 degrees. Therefore, white steel is suitable for the general milling machine, and the alloy milling cutter is suitable for the CNC machining center.
For fine milling, it is better to select a grinding blade. This kind of blade has better dimensional accuracy, so the positioning accuracy of the blade in milling is higher. Besides, better machining accuracy and surface roughness can be obtained.
In addition, the development trend of grinding milling inserts used in finishing is to grind out the chip groove to form a large positive rake cutting edge. It allows the blade to cut on a small feed and a small cutting depth.
The carbide blade without a sharp front angle. When cutting, the tip will rub the workpiece, the tool life is short. It is more suitable to select a pressing blade in some processing occasions. Sometimes it is necessary to select a grinding blade.
The best choice for rough machining is the pressed blade, which can reduce the processing cost. The size accuracy and sharpness of the pressing blade are worse than that of the grinding blade. However, the strength of the pressing blade is better. So it can bear the impact during rough machining and can bear the larger cutting depth and feed rate.
Sometimes there is a chip groove on the front face of the pressed blade. It can reduce the cutting force, reduce the friction with the workpiece and chips, and reduce the power demand.
However, the surface of the pressed blade is not as close as that of the milled blade. Also, the size accuracy is poor, and the height of each point on the milling cutter body is quite different. Because the pressing blade is cheap, it is widely used in production.
It can be used to mill viscous materials (such as stainless steel). Through the shearing action of the sharp blade, the friction between the blade and the workpiece material is reduced. Then the chip can leave from the front of the blade quickly.
As another combination, the pressing blade can be installed in the blade seat of most milling cutters. It is equipped with a polished scraper blade as well. The surface roughness of the scraping blade is better than that of the pressing blade. The application of the scraper blade can reduce the cycle time and cost. As an advanced technology, scraping technology has been widely used in turning, groove cutting and drilling.