A endmill is a rotary tool with one or more teeth used for milling (a machining method that uses a milling cutter as a tool to machine the surface of an object). When working, each cutter tooth intermittently cuts off the margin of the workpiece. endmill are mainly used for machining planes, steps, grooves, forming surfaces and cutting off workpieces on milling machines.
What principles should be followed when selecting endmill for machining
Do you know a few of them
● end mill selection
When choosing a endmill , you must pay attention to the cutter body and the tool holder.
Whether the end mill is used on CNC machining centers or on ordinary milling machines.
The material and hardness of the end mill . The specifications of the end mill, such as: blade length, overall length, blade diameter, shank diameter, etc.
If it is used on a CNC machining center, it should use solid carbide. For ordinary milling machines, you can use white steel.
The hardness of white steel end mill is softer than that of cemented carbide end mill. High-speed steel cutters are cheap, have good toughness, but are not strong, easy to use, and have relatively poor wear resistance and thermal hardness. The thermal hardness of high-speed steel end mill is about 600 degrees, and the hardness is about 65HRC. It is obvious that white steel is used for milling. In the case of harder materials, it is easy to burn the knife if the coolant is not in place. This is one of the reasons why the thermal hardness is not high.
Cemented carbide end mill have good thermal hardness, wear resistance, but poor impact resistance, and the blade will break if you drop it. Cemented carbide is a material made by powder metallurgy, and its hardness can reach about 90HRA. Up to about 900-1000 degrees. Therefore, white steel is suitable for ordinary milling machines, and alloy milling cutters are used for CNC machining centers.
Selection of end mill diameter
The choice of tool 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 size of the workpiece.
①Plane milling cutter. When selecting the diameter of a face milling cutter, it is mainly necessary to consider that the required power of the cutter should be within the power range of the machine tool, and the diameter of the machine tool spindle can also be used as the basis for selection. The diameter of the face milling cutter can be selected according to D=1.5d (d is the diameter of the spindle). In mass production, the tool diameter can also be selected according to 1.6 times the cutting width of the workpiece.
②End milling cutter. The selection of the diameter of the end mill should mainly consider the requirements of the workpiece processing size, and 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, the main consideration should be whether the maximum number of revolutions of the machine tool can reach the minimum cutting speed (60m/min) of the tool.
③Slot 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 should be within the allowable power range of the machine tool
Choice of milling cutter blades
For fine milling, it is best to choose a ground blade. This kind of blade has better dimensional accuracy, so the positioning accuracy of the cutting edge in milling is higher, and better machining accuracy and surface roughness can be obtained.
In addition, the development trend of milling inserts used in finishing is to grind out the chip flutes to form a large positive cutting edge, allowing the insert to cut at a small feed and a small depth of cut.
However, for carbide inserts without sharp rake angles, when small feed and small depth of cut are used, the tool tip will rub against the workpiece and the tool life will be short.
In some processing occasions, it is more appropriate to choose a pressed blade, and sometimes it is necessary to choose a ground blade.
It is best to choose a pressed blade for roughing, which can reduce the processing cost. The dimensional accuracy and edge sharpness of the pressed blade are worse than that of the sharpened blade. If you want to learn UG programming, the 304214709QQ group can help you but the edge strength of the pressed blade is better, impact resistance during rough machining and can withstand greater depth of cut And feed rate.
The pressed blade sometimes has a chip groove on the rake face, which can reduce the cutting force, and at the same time can reduce the friction with the workpiece and the chip, and reduce the power demand.
However, the surface of the pressed blade is not as tight as that of the ground blade, and the dimensional accuracy is poor. The height of the blades on the milling cutter body is quite different. Because the pressed blade is cheap, it is widely used in production.
The ground blade with large rake angle can be used for milling 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, and the chips can quickly leave from the front of the blade.
As another combination, the pressing blade can be installed in the blade seat of most milling cutters, and a polished scraper blade can be configured. The squeegee blade removes rough machining knife marks, and can obtain better surface roughness than only the pressing blade. Moreover, the use of doctor blades can reduce cycle time and reduce costs.
Scratching technology is an advanced technology that has been widely used in the fields of turning, grooving and cutting and drilling.
Choosing left-handed or right-handed milling cutter？
If the end mills can be easily distinguished, they can be divided into two categories: left-handed and right-handed. Many people still have no concept of left-handed and right-handed.
Right-handed milling cutter: First of all, the following methods can be used to determine whether the tool is left-handed or right-handed. In the face of a milling cutter placed vertically, if the flute rises from the bottom left to the top right, it is right-handed; if the flute rises from the bottom right to the top left, it is left-handed.
Right-hand rotation can also be ruled by the right hand. The four curved fingers are the rotation direction, and the thumb that is lifted up is the right-hand rotation.
Spiral flutes play the role of chip holding, and also constitute the rake angle and front part of the milling cutter.
Left-handed milling cutter: Generally, it is a kind of tool that is selected when high-precision machining is required. Left-handed milling cutters are generally used in mobile phone key processing, membrane switch panels, liquid crystal panels, acrylic lenses and other finishing processes.
However, there are some demanding ones, especially the production and processing of some mobile phone buttons or electrical panels. The precision and finish are also very demanding. It is necessary to choose the lower row of cutting and turning left, so as to avoid the whitening of the knife edge and processing. Pieces of incisions and other phenomena.
In the entire manufacturing industry, the tools used in processing are usually right-handed tools. For milling cutters, the groove of the blade determines the discharge direction of the chips cut during milling.
For precision parts, it is recommended to use a left-handed tool. The left-handed tool requires a certain advantage in processing precision parts.
Tips
Milling cutter tips 1: The feed direction of the workpiece and the rotation direction of the milling cutter have two types: down milling and up milling
Milling cutter knowledge 2: Die milling cutter is evolved from end milling cutter
