Master Wire EDM in Four Simple Steps

Master Wire EDM in Four Simple Steps!

1. Not Everything Can Be Processed by Wire EDM

Before proceeding with wire electrical discharge machining (Wire EDM), it's crucial to analyze and review the design drawings and assess the feasibility of using this method based on your existing equipment.

The following scenarios are not suitable for Wire EDM:

•Narrow Slots: Parts with slots narrower than the wire diameter plus the spark gap.

•Sharp Internal Corners: Parts requiring internal corners without radii or with radii smaller than the wire diameter.

•Non-Conductive Materials: Materials that do not conduct electricity, such as ceramics or plastics.

•Excessive Thickness: Parts thicker than the machine’s column span.

•Large Dimensions: Parts longer than the effective travel length of the machine’s X and Y axes, especially when high precision is required.

Under conditions suitable for Wire EDM processing, select between medium-speed wire EDM (MWF) and slow-speed wire EDM (WEDM) based on the part’s requirements for surface quality and dimensional accuracy. For parts with very high dimensional accuracy and fine surface finish requirements, opt for a slow-speed wire EDM machine.

2. Preparation and Setup: Choose Wisely

Material Selection:

To minimize deformation during Wire EDM processing, choose materials with good forgeability, permeability, and minimal heat treatment distortion. Ensure the material undergoes proper heat treatment according to technical specifications.

Drilling Wire Entry Holes:

For enclosed holes and some punch dies, drill wire entry holes before Wire EDM processing. The position of these holes should align with the programmed starting point.

Selecting Electrode Wire:

•Medium-Speed Wire EDM: Typically uses 0.18 mm diameter molybdenum wire.

•Slow-Speed Wire EDM: Generally employs brass wire; other options include zinc-coated wires. Choose electrode wire diameters based on precision requirements, aiming for diameters no less than 0.2 mm to achieve higher cutting speeds and reduce the risk of wire breakage. Workpiece Fixturing and Alignment:

Select appropriate fixturing methods based on the workpiece shape and size. Use dedicated fixtures or custom-designed ones for different types of parts (e.g., plate parts, rotary bodies, block parts). After fixing the workpiece, check its perpendicularity, flatness, and alignment with the machine axes.

Wire Installation and Alignment:

Properly wind the electrode wire around the wire guides to maintain adequate tension. Use alignment tools like finders or spark testing to ensure the wire's verticality.

Wire Positioning:

Before cutting, accurately position the electrode wire at the starting coordinate. Modern CNC Wire EDM machines offer automatic edge and center finding functions for precise positioning.

3. Generate Code with Advanced Software: Programming

Programming is a critical step in Wire EDM processing. The CNC program directs the machine, and its accuracy directly affects the final product's shape and precision. In practice, most programs are generated automatically using specialized software.

4. Start Processing: Avoid Scrap

After programming, verify the CNC program to ensure its correctness before formal cutting.

Most Wire EDM machines provide program verification methods:

•Drawing Inspection: Check for syntax errors and confirm the program matches the design contours.

•Dry Run Testing: Simulate the actual cutting process to detect any collisions or interference, ensuring the machine's travel meets processing requirements.

For parts with high precision requirements or tight mold gaps, perform trial cuts using thin plates to check dimensions and fit. Adjust the program if necessary until verified. During processing, monitor and adjust electrical and non-electrical parameters to maintain optimal discharge conditions. After completing the cut, verify that the start and end coordinates match. If issues arise, take corrective measures promptly.