the First samples of the composite materials appeared in the times of Ancient Egypt. Most often, they consisted of 2-3 components. Each component had properties that were different from the other. A well-known material which has the end result of adding the hair in resin. More similar to modern analogs is Bulat, which is the result of the work of the metallurgy of the ancient era. In this material was achieved a combination of high carbon and low carbon steels. The result of this was that he had high strength characteristics.
However, the complexity of such a matearealow created the problem of treatment with no damage to their properties. In modern conditions, when the conveyor processes occurring at high speeds, this question becomes particularly relevant. The issue was resolved using special cutters.
What is a mill for composites?
In General, such a cutter is a tool designed for machining composites. The complexity of regulation of this type of materials is that during milling there is a likelihood of rupture of individual fibers and damaging the individual layers. Therefore, the cutter shall be of a design that would rule out these factors or reduced them to a minimum.
For this purpose, different approaches to tool design. For example, the height of the base of the cutting should be no less 3 mm. It allows to obtain partial cutting of the material. As a result, it is possible to bend composites with minimal residual deformation.
Not less important is the geometry of the tooth. The angles are chosen depending on the type of cutter and workpiece material properties. In General, the size of the front working angle is changed in the range from 20 to -10°. Smaller values are taken in the processing of composites based on steels with high strength. The rear angle can vary from 5 to 30°. Proper choice of these angles along with the other mentioned factors affect the quality of the processing.
currently known end and disc mills for processing of composite materials. It is advisable to consider them separately.
the Tool end of the execution consists of working part and shank. In turn, the first positioned teeth and grooves. From the side of the shank is the mounting on the machine spindle. The shank usually has a cylindrical shape.
Angle of sharpening the cutting edge can be 90 or 135°. To remove chips from the cutting area are grooves machined at an angle. The surface of the groove often has the shape of a segment of a sphere.
the cutter body is made of tool steel. Then by vypaivanija mounted carbide inserts. The use of such plates is due to stringent requirements for processing composites. In particular, to ensure the cleanliness of the surface of the slice.
For cutting of composite panels of a thickness of > 4 mm may be used a single-tooth milling cutter with helical flute. It is recommended to make a choice in favor of the tool with the ejection of the chips down. As is known, this allows to avoid problems with the digging parts of the workpiece.
Traditionally this cutter helical groove has a tilt angle of 35°. To increase the speed of emission, the size of the screw pitch shortens towards the end of the cutter.
Disk cutter for composite represents a gear. On the teeth there is a plate, usually made of hard alloy. The number of teeth varies from four to six. Their profile can have a tapered, arcuate or straight shape.
the angle of the teeth can have values from 10 to 20°. For a more secure mounting on the machine spindle or a router drilled is symmetrical relative to the axis of the bolt holes. This also helps to reduce the indicators of end and radial runout.
Application of special cutters for composites
Processing mills of this type are used in the following fields of activity:
— Avia-space industry;
In is mainly used to produce three-dimensional letters and facades. In the aircraft industry this tool is used for machining of aluminium composites, multi-layer honeycomb sandwich panels and carbon fiber. They can also be engraved on the surface of the material.
Variety of special cutters for composites
As mentioned above, these cutters are disc and end. In turn, the first may be subdivided according to the type of mounting plate on cutter with removable or brazed plates. The second can be divided according to the profile of the base of the teeth. Here is a well known V, U— shaped cutter.
Disk cutter with brazed plates
In this mill carbide inserts soldered in the teeth. This allows for perfect transmission of torque from the spindle to the cutting edge. Also generally improves the quality of processing by reducing the runout of the tool. Mainly used for milling composites with high hardness. However, this tool is not cheap. When blunting of cutting edges it is necessary to replace the entire milling cutter.
Disk cutter with removable plates
This mill was designed to reduce the cost of machining. In this rectangular plate is removable and secured by fasteners. Feature of this plate is that it is possible to carve up to four working surfaces. This allows to significantly increase the lifetime of one mill.
in addition, there are versions of this tool with the tangential arrangement of the plates. The values of the inclination angle is selected in the range from 5 to 11°. This design allows to increase the durability of the cutter as a whole.
V, U— shaped end mills
These cutters are used for milling the grooves on the composite for subsequent bending. This profile of teeth are made in the form of the letters V and U. Shank they generally cylindrical.
One can have a cutting edge angle of 90° or 135°. In this form it is possible to bend to 90°. For more acute bending angles apply U-shaped cutter. Groove for chip removal in V-shaped cutter is performed under the radius. While in U-shaped, it turned at a right angle.
a Composite is a rather specific material, therefore, to ensure good quality treatment is necessary to constantly monitor the status of the cutting edges. Also in this connection, you need to quickly remove chips from the cutting area. Otherwise, the material may crack on the fold line.