Hurry up and review the principles of WEDM, or the master will scold me again!

For the content of the previous article, I do not know much about the wire cutting, go back, I made up for the EDM wire cutting processing, after summing up some basic knowledge to be brought to you.

The objects to be processed include common metals, materials with high hardness alloy qualities, synthetic diamonds, semiconductor materials, ceramics with conductive properties, and ferrite materials.

In addition to general precision machining, we are able to process large-sized and thick workpieces, and have begun to enter the field of precision microfabrication.

The shape of the process is such that WEDM is not only suitable for the processing of two-dimensional contours, but also for the processing of three-dimensional shaped surfaces with various tapers, variable tapers, and different top and bottom shapes.

I. Fundamentals

The basic principle of EDM is the same as that of EDM moulding, which is also processed with the help of the electrode of the tool to the workpiece by the electric corrosion phenomenon that occurs when the impulse discharge is applied to the workpiece. However, EDM does not need to build a moulding electrode, but uses a moving wire (molybdenum or copper wire) as the electrode, and relies on the relative movement of the electrode wire and the workpiece in a horizontal plane to cut workpieces with various shapes, and if the wire is tilted regularly relative to the workpiece, it can also cut workpieces with a taper. It is also possible to cut workpieces with a taper if the electrode wire is tilted regularly relative to the workpiece, which is connected to the positive pole of the pulsed power supply and the electrode wire is connected to the negative pole.

II. Characteristics of EDM cutting process

EDM wire cutting has the characteristics common to EDM and is often used to process hardened steels and carbides. A large number of wire cutting machines today are all digitally programmable, and the process characteristics are:

Pros:

It is suitable for machining materials that cannot be easily processed by machining methods, such as hardened steel, cemented carbide, and heat-resistant alloys.

The use of metal wires as tool electrodes saves costs in electrode design, saves costs in electrode manufacturing, saves time, facilitates the processing of complex shapes, facilitates the processing of through holes with complex shapes, and enables nesting.

The die is machined with an arbitrarily adjustable concave/convex gap.

Drawbacks:

The material to be processed must be electrically conductive

Blind holes cannot be machined

Conventional machining makes it impossible to obtain right angles

EDM easily obtains right angles

1. No need to make electrodes compared to EDM moulding; (short production lead time)

2. The electrode wire moves along its length, with less loss during machining and higher machining accuracy (the molybdenum wire used in the fast-walking wire can be reused).

It has the ability to process precise, highly complex shapes and small internal and external surfaces, as well as materials with high melting points and materials with high hardness that are difficult to cut, but it can only process electrically conductive materials.

4. High processing efficiency, high material utilisation and low cost.

5. High degree of automation and easy operation.

6. Surfaces where the busbar is not straight and blind holes cannot be machined.

III. Processing

The positive terminal of the pulse power supply is connected to the workpiece and the negative terminal is connected to the electrode wire. The electrode wire moves back and forth at a certain speed, and it continuously enters and leaves the discharge area. A certain amount of liquid medium is injected between the electrode wire and the workpiece. The stepping motor drives the table and the workpiece to make relative movement in the horizontal plane, and pulse discharge is generated between the electrode wire and the workpiece. By controlling the relative movement trajectory between the electrode wire and the workpiece to follow up the feed speed, the workpiece with a certain shape and size can be cut out.

IV. EDM wire-cutting machine tools

Depending on the wire travelling speed that the electrode wire has, a distinction can be made between fast wire walking wire cutting machines, of which there is one type, slow wire walking cutting machines.

(1) High-speed wire-cutting machine

In this type of machine, the electrode wire will carry out high-speed reciprocating motion, usually the speed of wire travelling is in the range of 8 to 10m/s, the commonly used electrode wire is molybdenum wire, and the processing fluid is emulsion.

Economy is good, but the stability of silk transport is poor, the processing accuracy is relatively low, the surface is rough.

The machining accuracy that can be achieved today is in the range of plus or minus zero point zero one millimetre, and the surface roughness has a value between three point two microns and zero point eight microns.

(2) Low-speed wire-cutting machine

This type of machine, the electrode wire for low-speed unidirectional movement, and the wire travelling speed is usually less than 0.2m / s, commonly used electrode wire is copper wire, and generally disposable, processing fluid for deionised water.

Good stability of wire transport, high machining precision, good surface quality, but high cost.

Machining accuracy up to 0.001mm, surface roughness Ra

V. Determination of EDM wire cutting process route

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