center line machining

Situation That Can Not Use Center Line Machining

Analyze and review the processing drawings, and consider the feasibility of this process method according to the existing processing equipment. The processing cannot be realized in the following cases:

The narrow gap is smaller than the diameter of the electrode wire plus the discharge gap. No r angle is allowed in the inner corner of the figure, or the workpiece whose R angle is required to be smaller than the diameter of the electrode wire. Work piece of non-conductive material. Workpieces whose thickness exceeds the wire frame span. The machining length exceeds the effective stroke length of the X and Y carriage of the machine tool, and the workpiece with high accuracy requirements.

Situation That Can Use Center Line Machining

Under the condition of meeting the wire cutting process, it shall be determined whether to choose medium wire cutting or slow wire cutting according to the processing requirements of parts, such as surface quality and dimensional accuracy. Parts with high dimensional accuracy and good surface roughness shall be completed by slow wire cutting machine.

Steps Of Center Line Machining

1)Reasonable selection of workpiece materials

In order to reduce the workpiece deformation caused by WEDM, materials with good forging performance, good permeability and small heat treatment deformation should be selected. The workpiece materials shall be subject to standard heat treatment according to the technical requirements.

2) Machining threading hole

For the processing of closed holes and some punch, threading holes need to be processed before on-line cutting. The position of threading hole shall be consistent with the machining starting point specified during programming.

3) Select the type of electrode wire

In WEDM, molybdenum wire with diameter of 0.18 mm is generally used as electrode wire; The electrode wire for slow wire cutting generally adopts brass wire and galvanized wire. The diameter of the electrode wire can be selected according to the requirements of machining accuracy. Try to select the electrode wire with a diameter of no less than 0.2mm to obtain higher cutting speed and reduce the risk of machining interruption.

4) Clamping and correction of workpiece

According to the processing shape and size of the workpiece, select the appropriate clamping mode to determine the clamping position of the workpiece. If the clamping methods of plate parts, rotary parts and block parts are different, special fixtures or self-designed fixtures can be selected to clamp the workpiece. After the workpiece is clamped, it should be corrected. Generally, it is to check the perpendicularity and flatness of the workpiece clamping, and correct the axial parallelism between the workpiece datum plane and the machine tool.

5) Threading and proofreading

Correctly wind the electrode wire around all parts of the wire feeding mechanism to keep the electrode wire under a certain tension. Select suitable methods to correct the perpendicularity of electrode wire, such as using aligner to calibrate wire, spark to calibrate wire, etc.

6) Positioning wire

Before wire cutting, the electrode wire should be accurately positioned to the starting coordinate position of cutting. The adjustment methods include visual inspection, spark method, automatic alignment, etc. At present, CNC wire cutting machine tools have contact sensing function, automatic edge finding, automatic center finding and other functions. The alignment accuracy is high. It is very convenient for electrode wire positioning, and the operation method varies from machine tool to machine tool.

WEDM programming is the focus of the whole process. The machine tool is processed according to the NC program. The correctness of the program directly affects the machining shape, machining accuracy and so on. In actual production, automatic programming method is mostly used.