The milling machine completes the forming of metal by rotating the cutter and moving it along the axis on the workpiece. It is obvious that the position of the milling machine in machining is very important.
Although milling machines are primarily used to machine flat and square surfaces, they are also used for many other purposes. Skilled technicians can use milling machines to cut viewpoints, fillets, and boreholes, and can use some subordinate equipment of milling machines to process arcs, semicircles, and helicoids (using spiral tools - double spiral or multiple spiral tools). Using some special tools on the milling machine can also process gear teeth, dovetail grooves and T-shaped grooves. More importantly, when machining the above workpiece shape on the milling machine, it can be completely manually operated, without the use of computer numerical control!
Now, if we use computer control to drive the spindle of the milling machine, the scale of workpieces that can be processed will be larger. Using the computer aided design/computer aided production generation program to control the milling machine, it is almost possible to process workpieces of any shape. As long as the workpiece shape can be displayed on the computer screen, it can be basically milled.
Milling operation.
The basic operations in 12 can be divided into four types:
(1) Face milling - cutting the plane with the tail of the cutter teeth.
(2) Profiling cutting - machining the profile of the workpiece with the side face of the cutter.
(3) Drilling.
(4) Boring - forming an internal circular surface.
1. End milling
The cutter is located below the surface of the workpiece at the required cutting depth, and then the workpiece is engaged with the cutter in a specific radial direction, which is called radial engagement. Radial engagement is expressed as the ratio between the length of the tool and the workpiece in the radial direction and its diameter. Face milling can be processed with three different milling cutters:
Face milling cutter:
This kind of tool is specially made, and the primary materials are high-speed steel and hard alloy. The insert type cemented carbide cutter is commonly used in industry up to now. The face milling cutter can achieve 64 medium high fine grinding, which may achieve more desired accuracy.
End milling cutter:
Because their end faces and circumference have teeth, this kind of cutter is used to cut the end faces. When the end teeth are used for grinding, the end milling cutter cuts straight into the workpiece. Similar to drilling, the face milling cutter cannot drill, so when it does not touch the workpiece, it is necessary to fix the DOC. End milling cutters with 2 or 4 teeth are very common, while end milling cutters with 3 teeth often use some high-speed cutting metals, such as aluminum. A few end milling cutters are made of cobalt high speed steel, which has higher hardness and durability than the end milling cutters made of standard high speed steel, but cobalt cutters are more expensive. The remaining cost of this kind of cobalt high speed steel is sometimes unreasonable, unless it is in the case where the cutting edge of cemented carbide tool is broken and cannot be machined due to mechanical vibration or the general high speed steel alloy is blunt due to the simple hardness of the workpiece.
The end milling cutter is sometimes replaced by all hard and feed cutters. Its cost is higher than that of high-speed alloy steel, but its cutting speed is 3 times that of high-speed alloy steel. The end milling cutter sometimes adopts the way of inserted carbide. The end milling cutter can achieve a medium finish. When machining the surface, it can be comparable with the face milling cutter at a relatively low speed.
Throwing knife:
Flying cutter is a single tooth surface cutting cutter. Because of its low cutting speed, this cutter is mostly used for installation rather than in large-scale production. Fly to a flat surface that needs to be placed very precisely or even more lubricated. The inserted high-speed steel or hard alloy cutter head of the flying cutter is clamped with something similar to the lathe head. Although the flying knife is very cheap and can be bought in shops, its cutting speed is very slow and there are serious security risks. The tool sensation and centrifugal force flying to the outer tail end are noteworthy work for flying knife cutting.
2. Circumferential incision
Circumferential cutting (also called shaping cutting), as its name implies, is to cut the inner and outer surfaces of the workpiece with the side teeth of the cutter. The commonly used circumferential cutting cutter for Z is the end milling cutter. We need to be alert to the direction of forward milling. We need to know that the difference of forces depends on the feed direction. When cutting with side teeth, the tool can be driven by the driving wheel along a certain path to the workpiece - called forward milling. In forward milling, the direction of rotation of the cutter in the workpiece always makes the processing feed axis and workpiece pass through the cut point. Maybe you can make the feed direction of the tool reverse along the circumference. The direction of the cutting teeth is opposite to the direction of the feed axis, which is called reverse milling. It is important to understand the differences between them for safety, service life and finish.
3. Step and cavity processing
Slotting to the cutting depth: Before machining the cavity, a hole should be first machined at the rough machining depth - this operation is similar to drilling, called a pin, and is completed with an end milling cutter, and then the cavity is machined with the side face of the milling cutter. The slotting milling of milling cutter with three grooves or four grooves can be completed by correctly grinding one or more teeth passing through the center surface. Most milling cutters with two grooves can perform plunge milling, but not all of them can! Some cutters with hollow centers and no cutting edges cannot be inserted and milled.
Cutting depth of bevel milling cutter: insert milling with the side face of the end milling cutter is called bevel milling or bevel milling for short. This method is not often used in manual operations. It is mainly used in numerical control processing because it is simpler to discharge chips than direct drilling, and it can make the coolant directly reach the processing part. Spiral insert milling has two advantages over linear insert milling. First, it can prevent the tangency between the cutter and the cavity, and then avoid leaving machining marks on the finished surface, which is called spiral bevel milling. The tool is spirally lowered.
4. Forming and cutting
Chamfering: Chamfering is generally used in the mold cavity and the places with feet outside, and the internal chamfer is generally called the internal fillet. The tooth line of chamfering cutter can be divided into internal concave and external convex. Machining workpiece with forming milling cutter in lathe is called forming processing. There are two kinds of end milling cutters used for machining concave angles, namely ball end milling cutter and round end milling cutter.
Customized molding: When the machining shape is special, the simple molding tool of Z in the workshop is a flying knife. Its high-speed steel blade can process workpieces of any shape without special equipment.
5. Drilling/Reaming
6. Boring
