Preparing a fabricator's game plan for jumping into waterjet cutting

A waterjet can deliver a high-quality edge when cutting metal. Accuracy can range from an average of +/- 0.003 in. to 0.001 in.

Diversification is a necessity for any metal fabricating company. It broadens the customer base, which eliminates the potential danger of having a few large customers representing the bulk of sales. And if done right, bringing in new customers introduces new market sectors to the mix, which acts as a hedge against slowdowns in other markets being served.

Introducing new fabricating capabilities is one way to find new customers, and the waterjet is one technology type to consider. A waterjet can cut various materials, including composites, plastics, and rubbers, and it has a sweet spot of 0.125 to 4 in. Having said that, some shops cut metals up to 8 in. on a regular basis.

Waterjets are also a good complement to other fabricating technologies found in most manufacturing companies. For example, a manufacturer of high-tolerance parts can use a waterjet to rough-cut metal blanks before they are placed in machining centers, eliminating an excessive amount of machining time. Production time for the machined parts that used to be measured in hours is now calculated in minutes.

On the fabricating side of metal production, a waterjet can cut parts that are ready to use straight off the table and can be sent directly to welding. Thermal processes, such as laser or plasma cutting, create a heat-affected zone on the cut edge of a part, meaning the microstructure and mechanical properties change. For several welding jobs to be successful, the material needs to exhibit the same properties as what is specified in the work order, which can mean the laser- or plasma-cut areas need to be ground back to the source material. Waterjet cutting helps to avoid secondary processing because it doesn’t put heat to the workpiece.

The case for adding a waterjet is a solid plan, but what does a shop need to know before jumping into the waterjet cutting world? Let’s go over a few considerations.

How Much Does a Waterjet Cost to Operate?

It is difficult to provide a straightforward answer because some of the factors influencing hourly costs are subject to change, particularly nowadays. Labor costs, for example, differ greatly from one part of North America to the other. Also abrasives, the garnet in the waterjet stream that wears the metal away during the cutting process, fluctuates in price, and shops use different amounts of abrasive. (A shop running a waterjet with a 100-HP, dual-pump system with multiple cutting heads is going to use a lot more abrasive than if it were running a 50-HP, single-pump system with one cutting head.)

But for a general guideline, the waterjet cutting industry typically suggests $22 to $25 per hour as a standard usage rate. (That shop running the 100-HP system is likely looking at $35 to $40 per hour, in case you were wondering.) That baseline figure provides company owners or managers something to work with as they try and determine a return on investment for a waterjet.

How Large of a Waterjet Is Needed?

The answer to this question is pretty straightforward—at least on the surface.

The size of the table should accommodate the dimensions of the material being placed on it, before it is cut. For many years, waterjet owners seemed to favor 4- by 8-ft. tables, but that’s changed as shops now order more 6- by 12-ft. tables.

Companies have a lot of choices when it comes to waterjet sizes—from small 1- by 1-ft. tables to very large tables, say 46 ft. by 13 ft.—so it behooves you to not only think about current cutting applications, but also those that might be on the horizon. If you are investing in a waterjet in anticipation of growing your business, plan for a larger table to accommodate those future opportunities. You don’t want to experience the same regret many shops have because you didn’t by a large enough waterjet table.

Advanced software makes today’s waterjets much more productive than previous generations of the technology.

Where Should the Waterjet Be Located?

First, look at where the water source is located in your shop and think about the water temperature. A waterjet operates better closer to the source and with cold water. A good water temperature target is one that does not exceed 70 degrees F. Hot water will adversely affect waterjet seals and high-pressure lines.

Second, waterjets can be placed next to other types of machinery. You don’t need a separate section in the building for your waterjet because these machines can be set up so they don’t splash water or create heavy dust. Material on the cutting table can also be submerged in water, which will make the cutting process cleaner and quieter. (When materials aren’t submerged, the process will generate a particulate mist that becomes a fine dust, settling on surfaces around the cutting area.)

There are waterjets that are designed to always cut with the material submerged, and these machines are commonly placed next to other expensive machine tools. For shops looking for another layer of protection, splash guards can be added to the table sides, and a small but growing portion of shops actually enclose the entire cutting area with a sort of hood covering the table.

What Sort of Water Quality Is Required?

Clean water equals longer machine life, lower maintenance costs, and less downtime. Water with concentrations of iron and calcium, along with dissolved solids, can deteriorate a waterjet’s pump, seals, and plumbing. That’s why it’s always advised that shops test their water to understand the water chemistry so that they can protect their investment. Testing is a part of routine maintenance and should continue over the machine’s life.

How Much Operator Training Is Needed?

Operating a waterjet is quite easy. As a result, the basic operator training usually takes a couple of days. The training also can be supplemented with online e-learning modules or instructor-led webinar training.

Most controls are Windows-based, so they should be familiar to anyone who has worked with a computer. The controller interface also is designed to be intuitive, which helps accelerate the learning curve.

The most important lesson learned during training relates to maintenance. The operator needs to be committed to maintaining the waterjet per manufacturer’s recommendations. Like a heart, the pump pushes high-pressure water throughout the waterjet system. When a responsible operator commits to regularly checking and replacing seals and hoses as specified, the waterjet will perform without issues.

What About Waste?

It is important to know the environmental regulations and follow them. Check the local and national regulations to ensure you are properly disposing of the wastewater.

Depending on the application, filters can be used to trap garnet and stock material particulate, so it is safe to drain. The garnet and particulate can then be collected from the filter, bagged, and disposed of safely.

In other instances, particularly where a toxic material is being cut, the waterjet operation may require a complete water recycling solution to avoid draining toxins and other contaminants into main lines.

For cleaning out the abrasive from the tank under the table, a shop can invest in a machine that collects the garnet and transports it into a hopper, which then can be moved with a forklift; hire a company to come and suck the materials from the tank; or do it the old-fashioned way with a few strong backs and some shovels. Any company running a waterjet for a full shift each week should plan to drain the tank about twice a year and remove the used abrasive and built-up particulate.

What Else Is There to Consider?

The technology is always improving, and waterjets made 10 to 15 years ago do not cut as well as the technology of today. If fabricators are only familiar with what older waterjets could do, they need to refamiliarize themselves with this technology.

Modern waterjets are rapidly evolving, and new capabilities are being introduced all the time. Machines are configurable based on a shop’s needs, and if you choose the right waterjet, upgrades to your existing machine are easy.

Any machine tool investment is a bit of a risk. Proper planning and understanding of what a waterjet can do for a metal fabricating company helps to maximize the return on your investment.