How to choose the milling inserts in CNC machining?

A milling insert is a rotating tool with one or more teeth used for milling (a mechanical machining method in which a milling insert is used as a tool to process the surface of an object). When working, each cutter tooth successively intermittently cuts off the spare amount of the workpiece. Milling Inserts is mainly used in milling machine processing plane, step, groove, forming surface and cutting workpiece.

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

A milling insert is used in a CNC machining center or a common milling machine.

Materials and hardness of milling cutter.

Specifications of milling insert, such as blade length, full length, blade diameter, shank diameter, etc.

If it is used in the CNC machining center, it should choose the overall carbide, ordinary milling machine can choose white steel.

White steel milling insert is softer than carbide milling insert. HSS tool cheap, good toughness, but strength is not high, easy to make knives, and wear resistance, relatively poor red hardness, high speed steel cutter red hardness of 600 degrees or so, around 65 HRC hardness, obviously when the white steel milling hard material, if the cooling fluid does not reach the designated position is easy to burn the knife that is one reason for the hot hardness is not high. Hard alloy milling cutter hot hard, wear-resistant, but poor impact resistance, just throw the blade will be broken, hard alloy is made of powder metallurgy method of materials, hardness up to 90HRA, thermal property up to 900-1000 degrees or so. Therefore, white steel is suitable for ordinary milling machine, alloy milling cutter CNC machining center.

1, the selection of milling inserts diameter

The choice of milling inserts diameter depends on the different products and production batch, the choice of cutter diameter mainly depends on the specification of equipment and the processing size of the workpiece.

① Surface milling inserts. When choosing the diameter of the plane milling insert, the power required by the tool should be considered in the power range of the machine tool, and the diameter of the spindle of the machine tool can also be used as the basis for selection. The diameter of the surface milling insert can be selected according to D = 1.5D (D is the diameter of the spindle). In batch production, the tool diameter can also be selected according to 1.6 times the cutting width of the workpiece.

② End mill. The choice of end mill diameter should consider the requirements of the workpiece machining size, and ensure that the required power of the tool within the rated power range of the machine tool. If it is a small diameter end mill, the main consideration should be whether the Z high revolution of the machine tool can reach the Z low cutting speed of the tool (60m/min). ③ Slot milling cutter. The diameter and width of the slot milling cutter should be selected according to the size of the workpiece and ensure that the cutting power is within the allowable power range of the machine tool.

2, the selection of milling inserts

① For fine milling, the best choice of grinding blades. This kind of insert has better dimensional accuracy, so the positioning accuracy of the inserts in milling is higher, and better machining accuracy and surface roughness can be obtained. In addition, the development trend of the grinding milling inserts used in finishing is to grind out the chip groove, forming a large positive front Angle cutting edge, allowing the insert to cut in small feed, small cut depth. The carbide inserts without sharp front Angle, when the use of small feed, small cutting deep processing, the tool tip will friction workpiece, tool life is short.

②In some processing situations, pressing blades are more appropriate. Sometimes grinding blades are also needed. Roughing Z is the best choice of pressed blade, which can reduce the processing cost. The dimension accuracy and edge sharpness of the pressing blade are worse than that of the grinding blade, but the edge strength of the pressing blade is better, and the impact resistance and can bear larger cutting depth and feed when roughing. The pressing blade sometimes has a chip roll groove on the front blade surface, which can reduce the cutting force, but also reduce the friction with the workpiece and chip, and reduce the power demand.

➂ but suppress the blade surface is not as close as grinding blade, poor dimensional accuracy, in the cutter blade on the blade height. As the pressing blade is cheap, it is widely used in production.

➃ ground before the big Angle blade, can be used for milling the cohesive materials such as stainless steel. Through the shear action of the sharp blade, the friction between the blade and the workpiece material is reduced, and the chip can be removed from the front of the blade faster.

➄ as another kind of combination, can suppress the blade is installed in most of the cutter blade, relocation strickle blade grinding. Scraping blades can remove rough machining marks and get better surface roughness than pressing blades alone. And the application of scraping blade can reduce the cycle time and cost. Scraping technology is an advanced technology, which has been widely used in the fields of turning, slotting and drilling.

3, the choice of milling inserts

The price of imported milling cutter is more expensive, a diameter of 100mm face milling cutter body price may be more than 600 dollars, so should be carefully chosen, in order to achieve the real specific processing needs.

➀ First, we should consider the number of teeth it has when choosing a milling cutter. For example, diameter of 100mm coarse tooth milling cutter only 6 teeth, and diameter of 100mm dense tooth milling cutter can have 8 teeth. The size of tooth spacing will determine the number of cutter teeth involved in milling cutting and affect the cutting stability and the requirement of cutting rate. Each milling cutter manufacturer has its own series of surface milling cutter with thick teeth and dense teeth.

➁Rough teeth milling inserts are most used for rough machining because they have large chip pocket. If the chip pocket is not large enough, it will be difficult to roll chips or aggravate the friction between the chip and the tool body and the workpiece. At the same feed speed, the cutting load per tooth of coarse tooth milling cutter is larger than that of dense tooth milling cutter.

➂ The cutting depth is shallow when it do the finish-milling, generally 0.25 -- 0.64 mm, each tooth cutting load small (0.05-0.15 mm), the power is not big, we can choose milling cutter, and can choose larger feeding. Because the metal cutting rate is always limited in fine milling, the chip pocket of dense tooth milling cutter is smaller.

➃ Larger specifications can also use the secret made rough milling cutter for cone hole is big and the spindle rigidity is good. Due to the dense tooth milling inserts at the same time there are more teeth involved in cutting, when using a larger cutting depth (1.27-5mm), we should pay attention to whether the power and rigidity of the machine tool is enough, whether the milling cutter chip pocket is large enough. Chip removal needs to be verified by test. If there is a problem with chip removal, the cutting dosage should be adjusted in time.

➄ rough milling under heavy load, large cutting force can make the poor rigidity of machine tool vibration. This kind of vibration can cause the carbide blade to break and shorten the tool life. The choice of rough tooth milling cutter can reduce the requirement of machine power. Therefore, when the main shaft hole size is small (such as R-8, 30#, 40# taper hole), can be effectively milling with coarse teeth cutter.

4, milling cutter choose left or right hand knife

If the end mill is simple to distinguish, it can be divided into two categories of left and right rotation. Now, a lot of people have no idea what right and left handedness is.