Electrical-discharge Wire Cutting / Traveling Wire EDM

Introduction Input Pre-requisites Production Batch Output Co-requisites Duration

	Facility: Charge / Free (*)	Material: Self-supplied	Mould / Pattern: N/A	Digital data: CAD file / CAM file / NC Program
	Location: W503 Non-conventional Machining Workshop Contact: T.W. Chan Office: Room W503a Telephone: (852)2766 7601 Facsimile: (852)2334 4634 E-mail: ictwchan@polyu.edu.hk * Depends on production volume, please consult responsible staff beforehand.

Introduction:

EDM wire cutting is a kind of EDM, their major difference is EDM wire cut use a round wire as the electrode to travels through the work piece. In EDM wire cutting, the wire moves down through the work piece. As in conventional EDM, the sparks arcing to the work piece from the electrode act like small teeth, each removing a small amount of metal. This results in a narrow tool path (kerf) being machined in the work piece; the wire travels inside this kerf. This process is sometimes compared to band saw cutting, because both processes can be used to cut intricate shapes from a metal work piece. 

The photo on the top shows a EDM wire cut machine. For simple cutting, tool path can directly be input through the control panel next to the machine.	Photo on the top shows a EDM wire cut machinine cutting thick metal stock. The work piece is placed in a dielectric fluid and the wire moves down through the work piece.

Input:

Almost any electrically conductive material can be cut. It can even be used to cut hardened materials. As there The size of the work piece must be under 780 x 685 x 200 mm. The diameter of the copper wire is 0.25mm so the smallest kerf can be achieved is 0.3mm. It is usually used to cut the following materials-

• Steel
• Copper
• Aluminum
• Graphite
• Tungsten Carbide

Pre-requisites:

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To prepare the material for wire cutting, the following processes can be used-

• Sawing
• Milling
• Turning
• Grinding (Usually be used to prepare datum for accurate wire cutting)
• Drilling (Usually be used to prepare starting hole for wire cutting, the hole should be drill at the un-wanted part of the product.)

To prepare the NC program for wire cutting, the following methods can be used-

• Prepare a 2D CAD file in the following in the format of "iges" / "dwg" / "dxf" and then use Master CAM to generate the CAM file or NC program.
• Use CAM software to generate the NC program directly. 
• For simple shape, the control panel can directly be used to control the tool path for cutting.

Production Batch:

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Number of Product at a time: 1 to many (depends on the thickness and the geometry of the product)

Time for each run: strongly depends on the thickness and the shape of the product.

Output:

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The material usually splits into two parts after cut. The outer part of the product form a shell and the inner part form a core. The product can either be the shell or the core so the starting hole must be made on the un-wanted part of the product. By inclining the wire, conical shape can also be formed. Undercut might be formed by two successive cut after re-orientation of the product. Many products of the same shape can be cut together by laminating thin sheets together. 

Co-requisites:

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Duration:

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It usually takes half days for CAD/CAM file conversion. However, for EDM wire cutting, the duration is strongly depends on the thickness and the geometry of the product. It takes several minutes to several days.