Milling cutters are generally multi-edged cutters. Since there are many teeth involved in cutting at the same time, the cutting edges are long, and a high cutting speed can be used, the productivity is high. Different milling cutters can be used to process planes, grooves, steps, etc., as well as tooth profiles of gears, threads, spline shafts and various forming surfaces.
The structure of the milling cutter
Take the indexable milling cutter as an example:
1) Main geometric angles
The milling cutter has a leading angle and two rake angles, one is called the axial rake angle and the other is called the radial rake angle.
The radial rake angle γf and the axial rake angle γp, the radial rake angle γf mainly affects the cutting power; the axial rake angle γp affects the formation of chips and the direction of the axial force. When γp is a positive value, the chips will fly away from the processing noodle.
Rake angle (contact surface of rake face)
Negative rake angle: for steel, steel alloys, stainless steel, cast iron.
Positive Rake Angle: For viscous materials and some superalloys.
Front corner center: for threading, grooving, profiling and forming knives.
Use negative rake angles whenever possible.
Milling cutter geometry
First up: positive angles - positive angles
The cutting is light and fast, and the chip removal is smooth, but the cutting edge strength is poor. Suitable for processing soft materials and stainless steel, heat-resistant steel, ordinary steel and cast iron, etc. This form should be preferred for low-power machine tools, insufficient rigidity of the process system, and built-up edge.
Advantage:
+ smooth cutting
+ smooth chip removal
+ good surface roughness
Disadvantages:
- Cutting edge strength.
- Not conducive to cutting contact.
- The workpiece is released from the machine table.
Followed by: Negative Angle - Negative Angle
Strong impact resistance, with negative inserts, suitable for rough milling cast steel, cast iron and high hardness, high strength steel.
However, milling consumes a lot of power and requires excellent rigidity of the process system.
Advantage:
+ cutting edge strength
+ productivity
+ pushes the workpiece towards the machine table
Disadvantages:
- Higher cutting forces
- chip jamming
And finally: Positive angle - Negative angle
The cutting edge has stronger impact resistance and the cutting edge is sharper. Suitable for machining steel, cast steel and cast iron. When milling with large allowance, the effect is also better
Advantage:
+ smooth chip removal
+ favorable cutting forces
+ wide range of applications
3) Milling cutter pitch
1) Close teeth: high-speed feed, high milling force and small chip space.
2) Standard tooth: regular feed rate, milling force and chip space.
3) Coarse teeth: low-speed feed, small milling force and large chip space.
If the milling cutter is not equipped with a dedicated wiper insert, the surface finish depends on whether the feed per revolution exceeds the width of the wiper flat of the insert.
Sharp tooth milling cutters can be divided into the following categories:
(1) Face milling cutters include integral face milling cutters, tooth-inserted face milling cutters, machine-clamp indexable face milling cutters, etc., which are used for rough, semi-finishing, and finishing various flat and stepped surfaces.
(2) End mills are used for milling step surfaces, sides, grooves, holes of various shapes on workpieces, and inner and outer curved surfaces. If the end mills are 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.
