Analysis of Electro-erosion Processing Technology for Polycrystalline Diamond Tools

In the automotive industry, the use of aluminum alloy materials and other non-ferrous metal alloy materials, such as plastic materials, synthetic carbon fiber materials, glass fiber materials and bonding materials, the use of diamond coating tools is also increasing. Polycrystalline diamond (PKD) tools are a tool that is often used in cutting high-hardness materials in recent years, and they also outperform carbide tools in the woodworking industry. According to experts, the annual sales of global PKD tools will exceed 350 million US dollars, of which 52% of PKD tools are used in automobile manufacturers and parts suppliers.

The processing cost of PKD tools is very high, and the price of the blanks is also very expensive. Cutting with PKD tools is time consuming and labor intensive, and the scrap rate is quite high. In addition to the manufacturing errors of geometry and size, due to the high brittleness of PKD materials, it is easy to form a chipping gap on the cutting edge, which is a description of the difficulty of precision tool manufacturers in the production and processing of PKD tools. In the development of PKD tools, it is now possible to be more economical and better to ensure the production and processing of this PKD tool. EDM is a good cutting method for machining PKD tools.

Integrated A-axis and measurement system
PKD is a sintered synthetic diamond billet. It has the structural shape of a metal cutting tool and is made of a hard material (tungsten carbide) as a base. This metal-based cutting material has a certain electrical conductivity, which makes it possible to perform electro-erosion wire cutting or electro-erosion processing of PKD tools. An important task in electrocorrosion processing is to produce a qualified insert on a sintered PKD blank. Another problem that needs to be solved by electro-erosion machining is to re-sharp the PKD tool mounted in the body to make it sharper. To this end, Agie equips their Agiecut lathe with a suitable generator, signal generator, new dedicated software, mechanical components and an A-slewing axis system.

The motor plays an important role in improving the electrocorrosive processing capability and electrocorrosion processing quality of PKD inserts. For example, Agie uses IPG (Intelligent Motor) and uses Ecut motor control technology to make the motor system of the machine tool applicable. For a variety of high speed cutting and electrocorrosion processing. The electro-etched cutting wire continuously cuts and corrodes different metal materials: hard materials and sintered materials in PKD inserts.

Precision, high-performance mechanical and electrical systems do not fully meet the needs of PKD blade sharpening, and there is no guarantee that a qualified or sharp-punched PKD insert can be produced cost-effectively. They must also rely on efficient software control programs.

Working closely with Aaco's Esco LLC, Agie has developed the EDMMap software for Windows. It generates NC measurements, electro-erosion machining and sharpening programs for rotary cutting tools based on the geometry of the tool. Accurately obtaining the actual position of the blade, the actual angle and the shape of the cutting surface are prerequisites for high-precision electro-erosion machining. It is best to measure these data directly in the production and processing machine, or in a five-coordinate measuring machine. All production preparation and cutting data should have the ability to call the network.

The CAD/CAM system is a must-have in the electro-erosion machining of PKD tools. The program control software can call CAD files in DXF format. The tool can measure the PKD blade at any angle and any position is the basis for obtaining accurate tool parameters. The parameters of the machine tool clamping components are stored in the database of the machine tool numerical control system. The cutting edge length and tool diameter can be defined by the operator. At the same time, the operator needs to give the sharpening direction, back angle and front angle of the PKD blade. Chamfer, the width of the chamfer and the number of cutting edges.

A large number of test points can accurately obtain actual geometric parameters
Electrocorrosion on the machine The machining of the PKD tool starts with the tool measurement (measuring the relative clamping length and angle of the tool in the tool coordinate system of the machine). During the measurement, the measuring system performs multi-point measurement on the tool insert, especially the data of a large number of cutting edges, which is prepared for the next electro-corrosion work. These detected tool and blade data ensure correct grinding of the cutting edge of the tool and facilitate tool size compensation for future use. To put it another way: After the cutting edge of a certain blade is broken, it can be dimensioned in the direction of many machine axes in the future to make a qualified product. In this electro-erosion process, a wire-cut copper wire is used, and the number of passes of the electro-erosion cut is set by the operator. The PKD insert is finally formed by corrosion cutting of a standard electro-erosion wire-cut copper wire (brass wire diameter 0.1 to 0.25 mm). The machining results of the NC program will be displayed graphically and saved.

In the cutting process of the PKD polycrystalline diamond blade blank, the cutting feed speed is 4 to 10 mm/min, which is related to the material and thickness of the blade to be cut, and the surface quality of the blade is related to the grain thickness of the blade. The sharpness of the cutting edge that can be achieved is 2 to 3 μm.