The groove milling cutter (see Fig. 4-60) is designed to leave grooves of corresponding specifications on the processed workpiece.
It is a milling cutter with a specific shape structure, which can cut stainless steel, iron pipes, copper pipes, aluminum pipes, non-metallic pipes, plates and other materials under high-speed rotation.
Fig. 4-60 groove milling cutter
1. Types of groove milling cutter
（1） End mill
The end milling cutter (see figure 4-61) is used to process grooves and step surfaces.
The cutter teeth are on the circumference and end face. Generally, they cannot be fed along the axial direction when working, but when there are end teeth passing through the center on the end milling cutter.
They can be fed axially.
Cutting edges include double edge, three edge and four edge, with a diameter of φ2~φ15mm, which are widely used in cut in milling, high-precision groove machining, etc.
Fig. 4-61 slotting end mill
（2） Three edge milling cutter
Three sided edge milling cutter (see fig. 4-62) is used to process various grooves and step surfaces, and there are cutter teeth on both sides and circumference.
The three side edge milling cutter used in cutting rectangular corners or grooves can be divided into staggered tooth shape with staggered cutting edges and parallel tooth shape with parallel cutting edges.
Parallel toothed trihedral edge milling cutter is the most commonly used, while staggered trihedral edge milling cutter is used for groove processing of steel.
In mass production, a large number of indexable cutters are often used, including semi trihedral edge milling cutters and full trihedral edge milling cutters.
All three sided edge milling cutters are mostly used for processing grooves.
Fig. 4-62 three face edge milling cutter
（3） Saw blade milling cutter
The saw blade milling cutter (see fig. 4-63) is used to process deep grooves and cut off workpieces.
There are many cutter teeth on its circumference.
In order to reduce the friction during milling, there is a 15 ‘~1 ° secondary deflection angle on both sides of the cutter teeth.
Features of the saw blade milling cutter: the grinding machine can be used to regrind the blade teeth for many times.
The service life of the grinded saw blade milling cutter is the same as that of the new saw blade milling cutter.
Fig. 4-63 saw blade milling cutter
（4） T-groove milling cutter
T-groove milling cutter (see fig. 4-64) is used to mill T-groove.
T-slot milling cutter can be divided into taper shank T-slot milling cutter and straight shank T-slot milling cutter, which can be used to process T-slots on various machine platforms or other structures.
It is a special tool for processing T-slots, and can mill T-slots with required accuracy at one time.
The end edge of the milling cutter has a suitable cutting angle, and the cutter teeth are designed according to oblique teeth and staggered teeth, so the cutting is stable and the cutting force is small.
Fig. 4-64 T-groove milling cutter
2. Selection method of common grooving milling cutter
In the slot milling process (see fig. 4-65), the tool selection is based on the type and size of the slot.
In the slot milling process, the three face edge milling cutter is generally preferred.
When processing closed grooves and non-linear grooves, the advantages of end mills are highlighted.
Generally, the following points should be paid attention to in the selection of slot milling cutter:
(1) The tool type needs to be selected according to the length of the groove, closed or open, straight or not straight, deep or shallow, wide or narrow.
(2) The tool selection is usually determined by the width, depth and length of the groove.
(3) According to the available machine type and operation frequency, it is determined whether end mills, long cutting edge cutters or three face edge mills should be used.
(4) Three edge milling cutter provides the most effective processing method for milling long and deep grooves with large amount, especially when horizontal milling machine is used.
Fig. 4-65 slot milling process
（1） End milling cutter selection method
When selecting end milling cutter, the workpiece material and processing position should be mainly considered. When machining materials with long strips of chips and strong toughness, use straight teeth or left-hand end mills.
In order to reduce the cutting resistance, machining can be carried out along the length direction of the tooth.
When cutting aluminum and castings, selecting a milling cutter with small number of teeth and large rotation angle can reduce the cutting heat.
During groove machining, the appropriate tooth groove should be selected according to the discharge of chips, otherwise chip blockage will often damage the tool.
When selecting end mills, you should pay attention to the following three aspects:
First, the tool is selected according to the condition that there is no chip blockage;
Then, honing the cutting edge to prevent edge collapse;
Finally, it is to select the appropriate alveolar.
The application of end mills in slot milling is shown in table 4-14.
Table 4-14 application of end mills in slot milling
|Vertical milling of grooves||Application type||matters needing attention|
|Milling groove with ordinary end milling cutter||1. closed slot 2. Shallow groove|
3. Full groove milling
4. non-linear groove
|1. Residual swing slot milling for difficult to cut materials (hard steel, HRSA, etc.) |
2. insert milling as a solution to the problem of long tool overhang
3. Easy to add additional semi finishing / finishing processes
|Corn milling cutter milling groove||1. rough machining slot milling |
2. Large removal rate
|1. In a stable high-power milling machine, shorter cutters can process grooves with the same maximum depth and diameter |
2. The tool should bear a very large radial force.
3. The best tooth pitch of various process types should be considered
（2） Selection basis of three side edge milling cutter
1. Number of cutting edges participating in cutting at the same time
When choosing a three sided milling cutter, we should choose from the processing materials, tool radius and feed rate.
For the cutting tool with small diameter, the change of cutting force on the cutting edge is easy to cause the bending of the tool body, so we must pay attention to the stability of load change.
2. Whether there is keyway
In general processing, there is no keyway. However, in the case of large feed and back feed or high-speed cutting, it is not enough to rely on the friction between the tool body and the handle to transmit the driving force. At this time, keyway should often be set.
When the outer diameter is greater than 100mm, it is better to set the keyway.
3. Flatness of side
It is difficult to improve the surface accuracy of the side of the groove if a three sided edge milling cutter with a relatively large outer diameter (relative to the inner diameter and the range of the cutting edge) is used to process the groove.
Especially, because a large number of chips will be mixed in the groove, even if the cutting speed is increased and the feed rate is reduced, the desired effect will not be achieved.
The solution to this problem is to adjust the side flatness error between 0.005~0.01mm when installing the three edge milling cutter on the spindle, and then chamfer the sharp corner of the cutting edge into an R-shaped surface.
There is also the use of large knife slots.
The application of three edge milling cutter is shown in table 4-15.
Table 4-15 application of three face edge milling cutter in slot milling
|Three side edge milling||Applicable to processing occasions||Not applicable to processing occasions|
|1. Open slot |
2. Deep groove
4. Cut off
5. Large machining range for different widths / depths
|1. Closed slot |
2. Linear slot only
（3） Application of saw blade milling cutter
When the saw blade milling cutter is used to mill grooves, because the diameter of the saw blade milling cutter is much larger than its thickness, it is easy to be affected by heating, which often leads to failure.
There are many reasons for heating, especially the cutting heat and the heating caused by the contact between the machined surface and the tool due to side deformation in cutting.
In order to reduce faults in the machining process, it is necessary to use cutting fluid and devices that can absorb chips in order to collect chips.
In addition, the two sides of the saw blade milling cutter should also be ground into an inward concave shape.
If the cutting edge is not hard, the heat will be more severe, so that the metal saw will bend or even break.
Therefore, always pay attention to whether the cutting edge is hard.
As for the correct use of metal saws, the use of cutting fluid and downward machining posture are the main principles.
The freedom of cutting speed selection is relatively large, but the feed rate is limited by the rigidity of the cutting edge. Pay attention to this, and then select various processing conditions.