EDM wire: Choose the best wire for your application- and save money

EDM wire is the workhorse of any wire EDM machine. But not all wire is made equal. This article explains how to choose the best EDM wire for your machining application.

Since the invention of electric discharge machining, EDM wire has been a crucial tool in manufacturing.

Then, just like today, EDM wire is essential as an electrode that can cut through metal by spark discharge. However, different EDM wires have specific properties that are important to consider before selecting.

When choosing the best type of EDM wire for your application, it’s essential to consider factors like tensile strength, surface area per unit length, diameter, and shape.

Estimated reading time: 7 minutes

Table of contents

EDM wire size

When you’re working with EDM, you have to be careful. Many things can go wrong; if they do, you’ll have a broken part and days of lost time- scrappage of both time and material.

You’ve probably heard that a good wire is a key to good finish and precision—and that’s true. But there’s more to it than just choosing the diameter: you have to think about what kind of power your workpiece needs.

Here’s how it works: the higher the power setting on your machine, the faster it can cut through metal. That means that thinner wires need lower power settings and longer machining times. Hence, for most machinists, using a thin wire is not preferred because they want their machining time to be as low as possible.

However, there are some benefits to using a thin wire. We can make impossible features very quickly- features that are difficult to make with any other manufacturing process!

Different types of EDM wire

If you work with a wire cut machine, you must be familiar with different EDM wires.

But what are the different kinds of EDM wires, and what are their differences?

There are a few considerations to make when considering the type of EDM wire you’ll use for a project:

-The types of materials can it cut through?

-What kind of coating does it have, if any?

– Its tensile strength

Let us take a look at the different types of EDM wire-

Soft Brass Wire

Brass is an excellent choice whether you want to cut metal or shape it. Brass has been used in metal manufacturing for more than 5,000 years and continues to be a popular metal for many applications.

For cutting metal, you can use 0.010-inch diameter brass wire. This plain brass wire is the most common type of wire used in EDM work—over 80% of EDM work uses this kind of wire.

You can use soft brass wire to cut tapers because it has low tensile strength. Hence, it won’t break as quickly if you try to cut at an angle.

Hard Brass Wire

As a wire-cut machinist, you know that hard brass is the best material for roughing and skimming cuts.

Hard brass holds up to aggressive dielectric flushing, so you can apply a higher voltage to the wire without breaking it. And that means faster cutting rates—which means more cutting and hence more profit!

But what if I told you there was another reason hard brass is the best? It may sound ridiculous. But what if hard brass also helps you cut complex metals?

That’s right—harder metals like tungsten carbide were notoriously resistant to EDM techniques until recently. Now, thanks to hard brass as the electrode, machinists can use EDM techniques to cut tungsten carbide more efficiently!

Zinc-coated Brass Wire

Have you ever wondered about zinc-coated brass wire? If you haven’t, now’s the time to change that!

Zinc-coated brass EDM wire is pretty amazing. The coating acts as a shield against heat. If you’re working with brass wire and you don’t want the heat to damage it, the zinc-coated wire will help protect the wire from harm.

You might be wondering how this works exactly. Zinc has a lower melting point than brass, so it boils away first and takes in heat. Melting zinc helps keep the brass from overheating. With zinc-coated wire, less heat enters the wire, preventing damage to your workpiece.

Coated EDM wires also perform better mechanically. Zinc-coated brass has a rougher exterior finish than plain brass wires. The coated wire gives you even surface finishes that improve flushing and increase speed. You can get a 10 to 15% speed improvement—compared to plain uncoated wires!

High-Speed wire

You’ll often hear machinists talking about high-speed EDM wire or stratified wire. Such wires are nothing but wire with a copper core and a defused zinc outer layer.” It has the electrical conductivity of copper, which means it can cut at twice the speed of other types of wire. However, it’s also twice as expensive as different types. Plain copper wire is rare because it’s too soft and too costly. You will want to use this kind of wire for rough cuts.

No matter which type of EDM wire you select, please remember that you can use it only once. The wire cutting process degrades the wire. However, it can still be recycled and sold for scrap metal.

Wire Tensile Strength

According to an EDM wire expert- there are three things to consider when choosing an EDM wire: tensile strength, elongation, and linear density (weight per unit length).

These three properties determine how much force is needed to cut through a particular material by pushing the wire sideways in the cut zone between the electrodes. “The forces involved with cutting vary directly with tensile strength, so less energy is needed if you have a wire with higher tensile strength.”

One of the critical things to know about EDM wire is its strength. The tensile strength measures the stress that a material can handle before it breaks. The lower it is, the easier it is to break down.

The wire cut machine preloads the tension onto the wire. The wire may not touch the part during cutting. However, the machine’s wire drive feed mechanism stretches it. We can increase or decrease the tension depending on the cut.

Surface finish and EDM wire strength

The relationship between surface finish and EDM wire tension can be crucial for machinists.

It would help keep the wire tension low when rough cutting so the machine can cut quickly without breaking the wire.

When skim cutting, you need to increase the wire tension, which means slower speeds and lower voltage in the machine. Such settings allow you to achieve the maximum surface finish and precision.

Lights-out EDM Machining

Machinists can become more profitable by finding innovative ways to increase their machine productivity and usage.

One of these ways is a lights-out machining concept. The EDM wire machine can run unattended or without an operator, especially at night. Lights-out machining has several benefits for your business. It allows you to take advantage of cheaper electricity rates and lower costs overall because you’ll be running your machines at off-peak hours. You’ll also save on labor costs while still getting the most out of your devices, as they won’t be sitting idle when no one is monitoring them. There are no limits on how long you can continue producing parts with lights-out machining—you just set up your machines to run!

Buying EDM wire for lights-out machining

The benefits of lights-out machining are clear: you can save money, improve machine use and throughput, reduce setup time and labor costs, and minimize the risk of human error.

However, even if you already have a lights-out strategy, there’s always room for improvement. One of these ways to achieve lights-out machining is the way you buy EDM wire. With the standard spools in the market, you can gain about 8 to 10 hours of uninterrupted cutting. However, we also get larger spools these days with using which you can cut close to 40 hours with continuous cutting.

Automatic rethreading

It’s a pain. You’re in the middle of a big job, and your wire suddenly breaks. Instead of just continuing where you left off and finishing up, you have to stop what you’re doing and take care of the mess.

Almost all new CNC wire EDM units have an automatic wire rethreading system. So you can focus on what’s essential and leave the wire rethreading to the machine.

Codes in the program control cutting and rethreading of the wire. If the wire breaks accidentally, the machine senses the gap, rethreads the wire, and resumes cutting where the wire broke. Automatic threading enhances unattended operation by making it possible to produce multiple openings or features within a part in a single setup.

Conclusion

In conclusion, remember that the wire is the most critical component when using an EDM machine. It’s what makes the EDM machine go!

For best results, consider your workflow and the end goal of your job. Your wire’s shape, size, and material should depend on maximizing efficiency and saving time.

By making these considerations and knowing which type of wire is right for each job, you can save time, money, and hassle both in the short and long term.

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