Water Jet vs EDM

If we look at the manufacturing industry a century ago compared to the market today, the changes would be nothing short of surprising.

Earlier, there used to be just one or two technologies for cutting and processing materials. The main factor that decided the quality of the final product was how skilled the labor was.

Today, there are many innovative cutting technologies and other cutting methods available. Choosing the perfect one can be a challenge.

Waterjet cutting and EDM cutting are two of the most common cutting methods.

Let’s examine waterjet vs EDM cutting and how they outperform other cutting methods. Based on the information provided here, you can finalize which cutting method to use for your business.

What is the Difference Between Water Jet and EDM Cutting?

While both water jet technology and EDM are used for the cutting process, their functioning and basic principles are worlds apart. Let us understand the basic overview of these two cutting methods.

Waterjet Cutting

A waterjet cutting machine accomplishes the cutting action by shooting a high-speed stream of water at the point of the intended cut. The high-speed waterjet produces the cutting action, even for very thick materials.

When using a waterjet machine for creating high-speed cuts in thin materials, a special nozzle or cutting head with minimal thicknesses can be attached to the waterjet machine. The resulting water comes out at a speed that can be three times the speed of sound.

EDM Cutting

EDM (also known as wire EDM) stands for Wire Electrical Discharge Machining. In EDM cutting, the cut material disintegrates when an electrically charged cutting wire passes through the object to be cut. The technique is used for cutting conductive materials.

The science behind Wire EDM cutting is quite a lot more complex than water jet cutting. It uses an electrode to produce an electric spark. Both the electrode and the workpiece (the workpiece is the metal that requires cutting) are submerged in a liquid dielectric medium.

During cutting, the metal fragments (eroded particles) from the cut materials break away from the rest of the piece and travel towards the electrode through the dielectric medium.

Water Jet Cutting vs EDM Cutting – Which is the Superior Technology?

Choosing the superior technology between waterjet technology and Wire EDM cutting requires careful analysis of the important factors that matter in the cutting of materials. Let us glance through these factors:

Upfront Cost

  • A wire EDM cutting machine for 90% of applications costs from $100,000 to $150,000.
  • Expect to pay $40,000 to $250,000 for a water jet machine – depending on applications.
  • While there are cheaper and expensive options in waterjet technology, the average price for both machines is the same. So there is a tie in this regard.

Running Costs

  • For Wire EDM, the main operating costs come from the wire. Other costs include minor consumables and electricity.
  • The water mixed with abrasives in water jet cutting account for the main running costs. Other expenses include items such as the nozzle heads.
  • Wire EDM machines have lower running costs compared to abrasive water jet cutting machines. If using pure water jet cutting, EDM machines lose the advantage.

Productivity and Cutting Speed

  • EDM machines are very slow and usually cut at a speed of ~0.4 inches per minute. So parts cost more to produce.
  • Waterjet cutters can cut at high speeds, about 6 inches per minute.
  • Waterjet cutters are around ten times faster than EDM cutters. You can cut ten times more in a given time, leading to greater productivity with waterjet cutters. Abrasive waterjets slice through material quickly and easily, even on a lower power setting.

Lifespan

  • The parts of a wire EDM cutter wear out quickly due to constant wear and tear.
  • The parts of waterjet cutters have a long life and can last thousands of hours, except the nozzle heads.
  • Waterjet cutters have a longer lifespan than EDM cutters.

Range of Supported Materials

  • Wire EDM cutters are limited to cutting electrically conductive materials such as metals and graphite.
  • Waterjet cutters are not limited to cutting only conductive materials and can cut through thick and thin materials. They can also handle reflective materials, which lasers can’t. Exceptions include diamond and tempered glass.
  • When it comes to the range of supported materials, there is hardly a debate as waterjet cutters can handle more materials – and so win by a large margin.

Maximum Cutting Thickness

  • Wire EDM machines can cut a limited maximum thickness of 16 inches of material.
  • Waterjet cutters can cut thicker parts and pierce holes up to a maximum of 30 inches in the material. In mining, waterjets can cut up to 100 ft of thickness.
  • Waterjet machines win again, handling about twice the maximum cutting thickness. This means that they have more cutting power than Wire EDM machines.

Cutting Tolerances & Accuracy

  • Carefully controlled EDM machines can provide better tolerances, as low as 0.0001″ and produce radii smaller than 0.001”.
  • Water jet cutting machine can provide tolerance of about 0.001″. They provide less precision but leave most of the cut material intact – which can be reused or recycled.

EDM machines have a lower cutting tolerance, making them more precise and accurate than water jet cutting machines. Especially when various skim cut passes using a low-pressure flush are completed. Skim pass cutting is normal with EDM.

Stress Caused to the Material During the Process

  • Wire EDM accomplishes the cut due to a rise in temperature at the point of electric breakdown. Therefore, there is stress caused in the nearby material.
  • Water jet cutting causes no stress to the rest of the material as there is no direct contact and no rise in temperature.
  • Waterjet cutters have an advantage when it is crucial to preserve the integrity of the material and ensure there is no stress on it.

Safety

  • EDM involves high currents in the material that is cut. There is also a lot of waste which makes this option less safe.
  • Waterjet cutting happens in a closed-loop system. There are no high currents or any temperature rise. Therefore, it is a very safe cutting method.
  • Waterjet cutting is the go-to choice if you are extra cautious about the safety of your workforce.

Heat-Related Effects

  • Wire EDM leads to forming a visible heat-affected zone near the cut due to the high temperature used.
  • Waterjet cutting involves no high temperatures, therefore leading to no heat-related effects.
  • Waterjet cutting is the winner as it produces no heat-related effects.

Need for Secondary Finishing

  • If you want to remove material heat-related effects, the material will require secondary finishing.
  • Waterjet cutting does not require surface finish techniques since there are no visible deformations. So no secondary processing is needed.
  • Waterjet cutting is better since there are no added costs and time spent on the final surface finish of the material. It even leaves cut material intact for reuse.

Environmentally Friendly

  • The dielectric liquid in EDM needs to be constantly flushed, making it a less environmentally friendly method.
  • In waterjet cutting, all the water used is recycled by the system. The metal fragments from the cut can be sold as scrap.
  • Waterjet cutting is a highly eco-friendly method, ideal for companies that value green technology.

Energy Consumption

  • Electrical Discharge Machining typically consumes about 15 KW of electricity.
  • Waterjet machines typically consume about 20 KW of electricity.
  • EDM machines have a slight advantage when considering the difference in power consumption between the two cutting methods.

Maintenance

  • The parts of EDM machines wear out quickly and need frequent replacement.
  • Waterjet machines have long-lasting parts.
  • Waterjet machines result in lower costs on labor and parts.

Applications

  • EDM machines have high accuracy, so they are used for cutting metals, for example, making coinage dies, prototypes, and drilling small holes.
  • Waterjet machines can cut through anything, so they are used in many different types of industries such as aerospace, mining, and more.
  • Waterjet machines have considerably greater versatility and advantages than EDM machines, making them much more cost-efficient.

Waterjet vs EDM Comparison Chart

Factor Water Jet Cutting EDM Winner
Upfront Cost $40,000 – $250,000 $100,000 – $150,000 Tie
Running Cost Abrasives and Nozzle Heads Wire and Electrodes EDM
Cutting Speed & Productivity Can cut 6 inches per minute Can cut 0.4 inches per minute Water Jet Cutting
Lifespan Parts have a long lifespan Parts wear out faster Water Jet Cutting
Range of Supported Material Can cut through almost anything Only cuts through electrically conductive materials Water Jet Cutting
Maximum Cutting Thickness 30 inches 16 inches Water Jet Cutting
Cutting Tolerance & Accuracy 0.001 inches, accurate 0.0001 inches, very accurate EDM
Stress Caused to Material No stress Stress due to intense heat Water Jet Cutting
Safety Very Safe Moderately Safe Water Jet Cutting
Heat-Related Effects No heat-related effects Formation of visible heat-affected zones Water Jet Cutting
Secondary Finishing Requirement Not required Required Water Jet Cutting
Environment Friendly Very eco-friendly Not eco-friendly Water Jet Cutting
Energy Consumption ~20 KW ~15 KW EDM
Maintenance Less maintenance required Frequent maintenance required Water Jet Cutting
Applications Diverse applications like aerospace, mining, hardware, tools, reaming, shaping Prototyping, drilling small holes, coinage die making Water Jet Cutting

Final Verdict

The choice between waterjet cutting and EDM cutting machines is easy.

While both these machines cost more or less the same for the cutting process, waterjet cutters have ten times the cutting speed and productivity compared to EDM Cutters. This means you can cut ten times the length with waterjet cutters while spending less on maintenance and parts replacement.

When we add in all the other factors that matter, the scale only tilts more heavily towards waterjet cutters. The best part is that even if you buy the waterjet cutter for cutting metal, you can use it for a lot of additional materials and applications.

In fact, for cutting the same shape out of different materials, you can stack the materials on top of one another and process them through a waterjet cutter. You will be increasing your productivity exponentially.

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