The milling cutter used for milling is a rotary cutting tool with one or more cutter teeth. When working, each cutter tooth cuts the workpiece in turn to remove the workpiece allowance, so as to process the plane, steps, grooves and other structures, or cut the workpiece. In this process, both the blade and the knife body play an important role. Therefore, when choosing which milling cutter should be used, we need to consider the blade and cutter body comprehensively.
Selection of milling cutter blades
It is suitable to use pressed blades in rough machining and ground blades in finish machining.
Although the dimensional accuracy and sharpness of the pressed blade are not as good as those of the ground blade, and the height of each blade tip on the blade body varies a lot, which can not meet the accuracy requirements of finishing, its low cost and high edge strength make it have good impact resistance and can withstand large cutting depth and feed in rough machining. In addition, some of these blades are equipped with chip curling grooves on the rake face, which can effectively reduce the cutting force, reduce the friction between the blade and the workpiece and chips, and reduce the power demand. Therefore, the pressed blade is more suitable for rough machining.
The first factor to be considered in finishing is machining accuracy, so the grinding blade with compact surface and better dimensional accuracy, which can obtain higher positioning accuracy, has become an inevitable choice. The blade should have a large positive rake cutting edge, so as to ensure that the blade will not rub with the workpiece during small feed, small cutting and deep cutting, so as to shorten the service life of the blade. The milled large rake blade can be used to mill viscous materials, such as stainless steel. Through the cutting action of the sharp blade, the friction between the blade and the workpiece material is reduced, and the chip can leave the front of the blade faster.
Pressing blade and grinding blade can also be used in combination. The pressing blade is installed in the blade seat, and then equipped with a ground scraping blade. The advantage of this is obvious. Rough machining is realized by pressing the blade. Almost at the same time, grinding the scraping blade can remove the knife marks left by rough machining and achieve better surface roughness. This method enables the rough machining and finishing processes to be carried out at the same time, which greatly reduces the processing time and saves the processing cost. This method is not only suitable for milling, but also widely used in turning, grooving and other processing fields.
Selection of milling cutter body
The cutter body of milling cutter is usually costly and expensive. For example, the price of a face milling cutter body with a diameter of 100 mm may be as high as more than 600 US dollars, so we should be more careful when choosing the cutter body.
First of all, pay attention to the number of teeth when selecting the tool body. The size of tooth pitch will determine the stability of milling and the requirements for the cutting rate of the machine tool. Generally, the number of teeth of rough tooth milling cutter is small, the average cutting load of each tooth is large, and its chip holding groove is also large, which can effectively reduce the friction between the tool and the workpiece. It is suitable for rough machining, and requires large power during cutting. The dense tooth milling cutter has more teeth, less average cutting load per tooth and smaller chip holding groove, which is suitable for finishing. Due to the shallow cutting depth and low metal removal rate of finish machining, the power required is also relatively small.
The dense tooth milling cutter can sometimes be used for rough milling. For example, for the spindle with large taper hole specification and good rigidity, higher requirements are put forward for the rigidity and power of the machine tool and the size of the chip holding groove of the milling cutter. If the rigidity is not enough, it will cause the vibration of the machine tool and lead to the edge collapse of the cemented carbide blade, thus shortening the tool life. At this time, it is still necessary to consider using a coarse tooth milling cutter with fewer teeth. If the chip discharge is not smooth, the cutting amount needs to be adjusted in time.