How to choose a milling cutter？

When choosing a milling cutter, pay attention to the cutter body and tool holder: 

1. Whether the milling cutter is used on a CNC machining center or an ordinary milling machine.

  2. The material and hardness of the milling cutter. 

  3. The specifications of the milling cutter, such as: blade length, overall length, blade diameter, tool holder diameter, etc.

If used in a CNC machining center, solid carbide should be used. For ordinary milling machines, white steel can be used.

White steel milling cutters are softer than cemented carbide milling cutters. High-speed steel knives are cheap, with good toughness, but not high in strength, easy to make knives, and poor wear resistance and thermal hardness. The hot hardness of the high-speed steel milling cutter is about 600 degrees, and the hardness is about 65HRC. Obviously it is used when milling with white steel. When it is hard, the coolant is not in place and it is easy to burn the knife. This is one of the reasons for the low heat resistance.

Cemented carbide milling cutters have good heat resistance and wear resistance, but poor impact resistance. If you just put down the blade, the cemented carbide will be made by powder metallurgy. The hardness can reach 90HRA. Can use heat. Up to 900-1000 degrees. Therefore, white steel is suitable for ordinary milling machines, and alloy milling cutters are suitable for CNC machining centers.

Milling cutter diameter.

The choice: The choice of milling cutter diameter varies greatly depending on the product and production batch. The choice of tool diameter mainly depends on the specifications of the equipment and the processing dimensions of the workpiece.

1 face milling cutter. When selecting the diameter of the face milling cutter, the main consideration is that the required power of the tool should be within the power range of the machine tool, or based on the machine spindle diameter. The diameter of the face milling cutter can be selected as D=1.5d (d is the spindle diameter). In mass production, the tool diameter can also be selected 1.6 times the workpiece cutting width.

2 end mills. The selection of the diameter of the end mill should mainly consider the requirements of the workpiece processing size to ensure that the power required by the tool is within the rated power range of the machine tool. If it is a small diameter end mill, you should consider whether the maximum number of revolutions of the machine tool can reach the minimum cutting speed of the tool (60m/min).

Three-slot milling cutter. The diameter and width of the slot milling cutter should be selected according to the size of the workpiece to be processed, and the cutting power is within the allowable power range of the machine tool.

Milling cutter selection:

1. It is best to use sharpening when finishing milling. The blade has good dimensional accuracy, so the cutting edge positioning accuracy is high during milling, and good machining accuracy and surface roughness can be obtained. In addition, the development trend of milling inserts for finishing is to grind chip flutes to form a large positive cutting edge, enabling the insert to cut with small feed and small depth of cut. For cemented carbide inserts without sharp rake angles, when using small feed and small depth of cut, the tool tip will rub against the workpiece and the tool life will be short.

2. In some processing occasions, it is more appropriate to use a press knife, and sometimes it is necessary to choose a sharpening knife. It is best to use a press knife for roughing, which can reduce the processing cost. The dimensional accuracy and sharpness of the pressed blade are worse than that of the grinding blade, but the pressed blade has better blade strength, impact resistance during rough machining and the ability to withstand greater depth of cut and feed. The pressed blade sometimes has a chip flute in the front to reduce cutting force, while reducing friction with the workpiece and chips, and reducing power requirements.

3. But the surface of the pressed sheet is not as tight as the grinding sheet, and the dimensional accuracy is poor. The height of each cutting edge on the milling cutter body varies greatly. Due to the low price of press blades, they are widely used in production.

4. The large rake angle blade after grinding can be used to grind viscous materials such as stainless steel. Through the shearing action of the sharp edge, the friction between the blade and the workpiece material is reduced, and the chips can be removed from the front end of the blade more quickly.

5. As another combination, a pressing knife can be installed on the blade holder of most milling cutters, and then a grinding blade can be fitted. The squeegee blade can remove traces of roughing tools and provide better surface roughness than using the press blade alone. In addition, the application of cutting blades reduces cycle time and costs. Scratch technology is an advanced technology that has been widely used in turning, grooving and drilling.

Choice of milling cutter body: milling cutter

The price is more expensive. The price of a face milling cutter with a diameter of 100mm may exceed $600, so choose carefully to meet the actual processing needs.

1. First of all, when choosing a milling cutter, the number of teeth should be considered. For example, a coarse-tooth milling cutter with a diameter of 100mm has only 6 teeth, while a fine-tooth milling cutter with a diameter of 100mm has 8 teeth. The size of the tooth pitch will determine the number of teeth involved in milling during milling, and affect the smoothness of cutting and the cutting speed requirements of the machine tool. Each milling cutter manufacturer has its own series of coarse and dense face milling cutters.

 2. The rough tooth milling cutter is mostly used for rough machining because it has a larger chip pocket. If the chip pocket is not large enough, it will cause difficulty in coiling or increase the friction between the chip and the workpiece. Under the same feed rate, the cutting load per tooth of a coarse-tooth milling cutter is greater than that of a close-tooth milling cutter.

3. When finishing milling, the cutting depth is fine, generally 0.25-0.64mm, the cutting load per tooth is small (about 0.05-0.15mm), and the required power is not large. You can choose a fine-tooth milling cutter, and you can choose a large feed rate. Since the metal removal rate of fine milling is always limited, there is no problem with the small chip flutes of fine-tooth milling cutters.

4. For spindles with large taper holes and good rigidity, fine-tooth milling cutters can also be used for rough milling. Since the fine-tooth milling cutter has a large number of teeth involved in the cutting at the same time, when using a large cutting depth (1.27-5mm), it is necessary to pay attention to whether the power and rigidity of the machine tool are sufficient, and whether the chip pocket of the milling cutter is large enough. The chip removal situation needs to be tested and verified. If there is a problem with chip removal, the cutting amount should be adjusted in time.

5. Excessive cutting force will cause chatter vibration of the machine with poor rigidity during heavy-duty rough milling. This chattering will cause the carbide inserts to collapse, thereby shortening tool life. The use of coarse-tooth milling cutters reduces the need for machine power. Therefore, when the spindle hole size is small (such as R-8, 30#, 40# taper hole), the rough milling cutter can be used for effective milling.