Waterjet Cleanout - Getting Rid of the Abrasive

The discovery and development of the abrasive waterjet cutting system came as a reprieve for the fabrication industry.  This is because the machine boasts a plethora of advantages over traditional cutting systems like punching, laser or plasma. Its efficiency, precision, flexibility, capability and productivity are unmatched. However, just like any other system, the machine requires regular maintenance to keep its performance at optimal levels. One maintenance task that this machine always needs is the removal of spent abrasive from the tank. The accumulation of abrasives in the tank can eventually fill up past the  working surface of the table. Therefore, waterjet cleanout should be done periodically using any of the following methods.

How Waterjet Cutting Works

Waterjets “cut” or rather grind their way through materials by using a mixture of high pressure water forced through a small orifice creating a jet stream at great velocity (over 2X the speed of sound!). The jet stream is then mixed with a sharp and hard abrasive called Garnet.  This abrasive mixture is then focused back into a jet stream through a Focus Tube (sometimes also called the nozzle) where it is then precisely directed into the workpiece and shapes are carved via the CNC control of the axis. 

During the cutting process the machines use anywhere from ¾ of a pound of abrasive to 2 pounds depending on the pump horsepower, pressure and application. The abrasive once having passed through the material is broken in smaller pieces and typically settles to the bottom of the worktank where over time, it builds up requiring removal manually or by some other automated or semi automated system. 

Tips for Cleaning Waterjets

There are a variety of ways to keep your waterjet running and operating efficiently with minimal downtime for abrasive removal and tank cleanout.  The important factor is to ensure you are keeping the tank clean and clear allowing your machine to continue operating. These options to clean out your waterjet are detailed below.

Automatic Abrasive Removal Systems

Boasting to be the newest and the most efficient technique to clean abrasive, automated abrasive removal systems have automated the waterjet cleanout process. These systems are integrated right into the tank of the waterjet cutting machine and operate automatically to keep the tank clean and clear of spent abrasives. This method is swift and highly reliable as it saves you time that would have been lost when using another cleaning technique. Because the removal system is integrated into the cutting machine, it requires minimal human input once it is installed. It helps you get rid of the abrasives while still allowing your equipment to continue with its routine operations. 

An automated abrasive removal system keeps your tank clean and eliminates the downtime & problems experienced during manual tank cleanouts.  It also reduces operational risks as you won’t require any employee to climb into the tank and do the cleaning. Running the removal system continuously is recommended as it ensures that the bottom of the tank, where the cleanout jets and nozzles are, doesn't get clogged with abrasives and other dropped parts. 

Advantages: Automated system requiring little to no interruption of the machining operation

Disadvantages: Investment and Operational Costs.

Portable Abrasive Extractors

Another great option is a Portable Waterjet Cleanout Device.  These Industrial grade wet vacuums use a large hose and nozzle to suck out the spent abrasive from the tank bottom. These vacuums are 1/3rd the price of the automated systems and can be used across multiple machines. You can even do the removal job yourself.

Abrasive extractors are designed in a way that they suck the abrasives up and out of the waterjet tanks. And since there are several kinds of extractors in the market, the type you’ll choose will determine whether slates and grates need to be removed. The extractor is manually hauled through the tank, sucking up the abrasives at sweeps across the waterjet tank. Although the cleanout that is done using abrasive extractors is less labor-intensive as compared to the next method discussed in this article, the operations of the waterjet machine must be halted for the cleaning process to take place. 

Advantages: No slat removal or digging out required 

Disadvantages: Machine Interruption, Requires access to all sides of the machine.

Shoveling Out the Waterjet Tank

The final method is shoveling. This is a common practice with new waterjet users. This method involves the removal of abrasives using a shovel or backhoe, however, for your cleanout to be thorough when using this method, you need to lock the waterjet, remove the grates and slates and drain the tank of water. If you're using a backhoe you need to be very careful not to damage the machine's motion components.  If you're using the manual method your employees will need to climb in the tank and start shoveling out the tons of accumulated abrasives. This is a full day project if done manually and one not to be taken lightly.

Although the time you’ll take to clear out the abrasives through shoveling will depend on the size of your waterjet tank, the number of people involved, and the magnitude of the abrasive material in the tank. It can take from a few hours to a couple of days. Like in the abrasive extractors, operations must also be halted if you’re using shoveling as your waterjet cleanout technique. However, before you let your staff climb into the tank, make sure they have adorned some protective gear to lower the risks of injury. 

After thorough removal of the abrasive, you can replace worn-out slates and resume normal operations. 

If this is the method you are using you can often greatly decrease your downtime by making catch boxes nested into the waterjet worktank.  once filled these boxed can easily lifted out by an overhead craven or forklift, dumped and returned making your waterjet cleanout process down to mere minutes. 

Advantages: No initial investment cost. 

Disadvantages: Machine Interruption, Time consuming and Difficult Labor. 

How to Handle Abrasive

Once removed the abrasive must be disposed of. The abrasive is non-hazardous, and in most cases can be removed to a local landfill easily (unless hazardous materials have been cut) Although there are several methods to use the 

Recycle Spent Waterjet Abrasive 

Recycling spent abrasive is everyone's first thought.  Abrasive is approximately 70% of the operating cost on the waterjet as it would make sense to reuse it back in the machine getting maximum mutilation.  Unfortunately the recycling systems available today are more expensive to operate then purchasing raw virgin abrasive and require enormous amounts of maintenance to keep operating making these systems unreliable and costly. 

Dumpster Haul Off

Most waterjetters will rent a dirt dumpster, have it delivered next to their machine and when full have it picked up.  This method is easy and quickly disposes of the spent material. 

Return It

Many Abrasive sellers offer a pickup service providing bulk bags that can be filled with your spent abrasive and returned to a recycling/fill yard.

Repurpose It

Don't forget that your used Garnet abrasive can be re-used in other applications such as sand blasting or added to concrete/block mixtures as an added hardener and filler.

Cleaning out and disposing of spent waterjet abrasive is just one of the many factors to consider when buying a waterjet cutting system. Let the experts at Southern Fabricating Machinery Sales, Inc. help you select the right machine and options for your needs.  Call us today at 1-813-444-4555 or visit us on the web at www.southernfabsales.com