Wire electrical discharge machining

Written By

Rushik Borad

Wire electrical discharge machining (EDM) is a manufacturing process that is used to cut complicate shapes through the use of an electrically charged wire. This process is known for its high precision, accuracy, and ability to cut hard and brittle materials.

In this article, we will explore the basics of wire EDM, how it works, and its applications.

Don’t forget to download the excel template in the below section. It has calculations for programming wire edm.

What is Wire EDM?

Wire EDM is a machining process that uses an electrically charged wire to cut through materials. It is a non-contact process that does not use physical force to cut the material. Instead, it uses an electrical discharge to erode the material, which is controlled by computer numerical control (CNC) programming.

How does Wire EDM work?

The wire EDM process works by creating an electrical spark between the wire and the work piece. The wire is made of a highly conductive material, usually brass, and is held between two spools. The work piece is submerged in a dielectric fluid, which serves as a coolant and a conductor of electricity.

When the wire approaches the work piece, a voltage difference is created between the wire and the work piece. This voltage difference creates an electrical discharge, which ionizes the dielectric fluid and causes a spark to jump between the wire and the work piece. The spark erodes the material, and the wire moves through the work piece in the desired shape, guided by the CNC programming.

The wire EDM process is highly precise and can cut through materials as thick as 300mm. It is capable of cutting complex shapes with tight tolerances and can produce a very fine finish on the work piece.

After all watch a video at the end of this article.

Calculations in wire EDM for programming

The calculation of Wire EDM involves several parameters, including wire speed, current, pulse duration, and spark gap. The calculation process involves determining the optimal settings for these parameters to achieve the desired cutting results.

These parameters are used for programming.

Wire speed: Wire speed is calculated based on the desired cutting rate and the thickness of the material being cut. The formula for calculating wire speed is:

Wire speed (mm/s) = Cutting rate (mm/min) / (60 x Thickness of the material being cut (mm))

Current: Current is determined by the wire diameter, the material being cut, and the desired cutting rate. The formula for calculating current is:

Current (Amps) = ((Wire diameter (mm) x Material density (g/cm3) x Cutting rate (mm/min)) / (1.85 x Pulse duration (µs))) ^0.5

Pulse duration: Pulse duration is calculated based on the wire diameter and the material being cut. The formula for calculating pulse duration is:

Pulse duration (µs) = 0.2 x (Wire diameter (mm) / Material resistivity (µΩ.cm))

Spark gap: Spark gap is calculated based on the wire diameter, material being cut, and current. The formula for calculating spark gap is:

Spark gap (µm) = ((Wire diameter (mm) x Material density (g/cm3) x Current (Amps)) / (0.7 x Cutting rate (mm/min))) ^0.5

By using these formulas and adjusting the settings for wire speed, current, pulse duration, and spark gap, operators can optimize the Wire EDM process for cutting a particular material to achieve the desired precision, accuracy, and surface finish.

It is important to note that these calculations are only a guide and may need to be adjusted based on the specific properties of the material being cut and the performance of the Wire EDM machine.

Applications of Wire EDM

Wire EDM is used in various industries, including aerospace, automotive, medical, and electronics. It is used to manufacture a range of parts, including gears, molds, dies, and components for engines and turbines.

One of the primary advantages of wire EDM is its ability to cut hard and brittle materials, such as tungsten carbide, ceramics, and tool steels. These materials are difficult to machine with conventional methods, but wire EDM can cut through them with ease.

Wire EDM is also used in the production of prototypes and small batches of parts. It is a cost-effective method of producing small quantities of parts with high precision and accuracy. It is also used in the manufacturing of intricate shapes, such as gears and turbine blades, where precision is crucial.

Advantages of Wire EDM

• High precision and accuracy: Wire EDM is capable of cutting very intricate shapes with tight tolerances, making it ideal for the production of high-precision parts.
• No mechanical force: Since Wire EDM is a non-contact process, it does not apply any mechanical force to the work piece, which reduces the risk of damage to the material.
• Ability to cut hard and brittle materials: Wire EDM can cut through hard and brittle materials that are difficult to machine using conventional methods, such as tungsten carbide, ceramics, and tool steels.
• Fine surface finish: Wire EDM can produce a very fine surface finish on the work piece, which reduces the need for additional finishing operations.
• Cost-effective for small production runs: Wire EDM is a cost-effective method of producing small quantities of parts with high precision and accuracy.

Disadvantages of Wire EDM

• Slow cutting speed: Wire EDM is a relatively slow process, which can increase the production time and cost.
• Limited material thickness: Wire EDM is not suitable for cutting materials thicker than 300mm.
• Material waste: Wire EDM generates a significant amount of material waste, as the wire erodes the material from the work piece.
• High equipment cost: The equipment required for Wire EDM is expensive, which can be a barrier to entry for small businesses.
• Need for skilled operators: Wire EDM requires skilled operators who have a thorough understanding of the process and the ability to program CNC machines.

Other important info

The cost of a wire EDM machine, maintenance cost, life cycle, and power consumption can vary depending on the manufacturer, model, and location.

Price: The price of a wire EDM machine can vary depending on the specifications and features. Generally, prices range from $30,000 to $200,000 or more for larger and more complex machines.

Maintenance Cost: The maintenance cost of a wire EDM machine depends on its usage and the frequency of maintenance required. Typical maintenance costs include replacing worn-out parts, such as wire guides, filters, and seals. The maintenance cost may range from a few hundred dollars to a few thousand dollars per year.

Life Cycle: The life cycle of a wire EDM machine depends on various factors such as usage, maintenance, and the quality of the machine. Generally, a well-maintained machine can last for up to 10-15 years or more.

Power Consumption: The power consumption of a wire EDM machine depends on its size, features, and usage. Typically, a wire EDM machine consumes around 5-15 kW of power per hour.

It is essential to consider the cost and maintenance of a wire EDM machine before purchasing one. Factors like the level of precision required, the material to be cut, and the desired production volume should also be considered when selecting a machine

List of Wire EDM Machines

1. Mitsubishi Wire EDM
2. Sodick Wire EDM
3. Makino Wire EDM
4. Charmilles Wire EDM
5. AgieCharmilles Wire EDM
6. Fanuc Wire EDM
7. ONA Wire EDM

Watch Video

Watch a video from Wisconsin Metal Parts, Inc. YouTube channel for knowing more about wire EDM. Click button below to watch video.

Rushik Borad @rushikborad

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