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High-precision plasma system automates Chromalox’s cutting, beveling processes

Plasma with mist assist helps to improve cut quality, throughput

An automated plasma system with water mist makes straight-wall holes on stainless steel pipe. The water reduces dross and prevents oxide formation, resulting in surfaces that are nearly weld-ready.

At Chromalox, Pittsburgh, a global manufacturer and supplier of electric heat and control products, industrial heating applications run the gamut. Some are ordinary, such as heating a small ship cabin, and some are unusual, like heating saltwater for manatees. Despite this variety, the company is always interested in adding market share and breaking into untapped markets, so implementing new technology is a top priority.

The drawback to any new machine or process is that even the perception of a steep learning curve can lead to a difficult and time-consuming transition. However, this didn’t stop the company from making a successful changeover from manual to automated pipe preparation, which improved workflow, resolved some persistent workforce issues, and helped to open the door to new market opportunities.

A Manual Start

Like many of the company’s facilities, Chromalox’s Ogden, Utah, location works with a large variety of metals, such as steel, stainless steel, INCONEL® alloy, and HASTELLOY®. The pipes used in these applications are from 4-in. Schedule 40 standard pipe to 48-in. Schedule 160 pipe and range from ¼ to 2 in. thick.

In a typical heating application, the pipe spool requires two beveled end cuts and either straight or beveled nozzle cuts in preparation for welding. Before it automated the process for cutting all of these materials, Chromalox hired skilled workers to lay the pipe and then use a drill press or grinder to manually cut and bevel the chamber.

“We needed to use a grinder with a cutting wheel to cut the pipe, and then we had to grind the bevels,” said Welding Engineer Christian Loya. “It was a manual, very labor-intensive process.”

Manually preparing the pipe requires a lot of skill—skill that is hard to find. Hiring workers who could hand-lay the pipe, as well as cut and bevel correctly every time, was an ongoing problem. Repeatability was the company’s biggest challenge.

“Cuts need to be made in an exact spot every single time,” said Loya. “And making sure the bevels are always correct has been an issue with doing it manually.”

Additionally, to find a skilled workforce, or even workers who want to learn this trade, is challenging.

“Once our workforce leaves and retires, we’re going to have a hard time replacing them because of the knowledge it takes to lay the pipe and do the prep work accurately,” said Loya. “It’s tough to figure out and manage all those calculations in your head, and fewer people are willing to do it.”

Enter Automated Technology

When a change from one process to another is being considered, the high probability of a steep learning curve can be the most challenging hurdle.

Figure 1
On some automated plasma cutting systems, the operator switches between processes simply by changing the consumables cartridge (shown here) and selecting the right variables in the plasma controller. The cartridge replacement takes seconds, and the entire process takes just a few minutes.

“I think when some people see an automated pipe system, or anything automated in general, they think ‘computers’ and ‘this will be tough for me to learn because I am not computer-savvy,’” said Loya. “But once we saw the Ultra-Cut 400 XT and the software that it came with, it was really easy. We took a hands-on approach with all the guys to learn the technology.”

Today’s high-precision plasma systems are more accurate and productive than the machines of yesteryear. A 400-amp unit cuts 1-in. steel at 80 inches per minute (IPM) and 2-in.-thick steel at 30 IPM.

In Chromalox’s case, investing in the integrated automated plasma system made by Thermal Dynamics delivered ISO Class 3 or better cuts on any material from gauge to 2 in. thick, noticeably reducing bevel variability and the need for postcut finishing (see the tables in the sidebar). The company coupled the plasma system to a 6-axis CNC pipe cutting machine from Watts Specialties Inc. for consistent, precise, fast cuts.

These days the work doesn’t trickle, it flows.

“The cutting process happens much more quickly, and we’re not holding up the welders,” Loya said. “We know we can cut a week’s worth of pipe in a day now instead of a month or more to do it manually.” In other words, production has not only improved, it’s also uninterrupted.

For prepping an entire heating system, the time it takes to cut has decreased more than 90 percent.

“It used to take us three to four hours to manually cut a chamber with two 37½-degree end cuts, as well as two nozzles cut at 37½ degrees on a perpendicular axis,” said Loya. “Now we can program it in and cut it within 10 minutes.” Changeovers from one process to another likewise take little time (see Figure 1).

More important, the cut quality enables pipe to go directly from the cutting table to welding without

expensive and time-consuming secondary operations. Chromalox also takes advantage of the Water Mist Secondary (WMS™) process to further lower costs, improve quality, preserve cutting speeds, and produce high-integrity welds on nonferrous metals (see Joint Preparation on Nonferrous Materials sidebar).

“The quality of the cuts is great,” said Loya. “Seeing what we did before manually, or even using a different power source without the water mist technology, is like night and day. The amount of time it takes to clean up a joint is [nearly] 100 percent faster now because it’s so minimal. And it cuts down on our consumables because we are not using nearly as many grinding discs and flap discs.”

Figure 2
Despite the trepidation that comes with learning a new technology, the staff at Chromalox embraced the opportunity to be more productive. Lead person Richard Loper adjusts cutting parameters on the Watts pipe cutting machine. The staff found that the Thermal Dynamics interface (inset) likewise was easy to learn and program.

Chromalox now uses a 120-grit flap disc versus a grinding wheel that was required for its previous plasma system, which didn’t have WMS. It uses less expensive tools and needs less time to finish. The discs also impart less stress to the material than grinding or chipping.

The inside of the pipe requires less work as well. Before, spatter adhered to the inside and had to be chiseled out. With WMS, the spatter doesn’t stick; it is easily removed by hand.

The 6-axis CNC pipe cutting machine also has made training easier.

“The acquisition of an easy-to-use system was something we really needed,” said Loya. “Now we can hire an operator instead of a skilled worker who knows how to lay pipe. With this software, we can train ourselves.”

Loya, who has a background working with 3-D software programs, was a bit more concerned about training some of his older employees unfamiliar with advanced programs, or even with computers. Richard Loper, lead person in the prep area, was initially leery of using the new program.

The graphical interface helped to make the transition easy (see Figure 2).

The Key to the Future

In addition to improving workflow and simplifying training for the workforce, automation has helped Chromalox expand into new markets.

“What’s great is that we’re expanding into different markets in the industry right now, and the thickness and size of our vessels was a big concern as far as getting the right cuts and bevels,” said Loya. “With a 400-amp power source, we have no issues with repeatability and we can cut 2 in. thick all day. The 100 percent duty cycle is great. It’s nice knowing that we have the right power source going forward.”

As Loya sees it, implementing new technology is what Chromalox is about, and automating is the key to moving successfully into the future. “We want to improve and add new technology to make things easier and workforce-friendly,” said Loya. “We need to automate as much as possible. What can we automate? It’s the key to the future of most companies and we’re moving into it.”

Joint Preparation on Nonferrous Materials

Many fabricators who work with nonferrous materials up to 1¼ in. thick remain unaware that a little moisture can be a big help. Dubbed Water Mist Secondary (WMS) by Thermal Dynamics, the misting process can reduce cutting costs by an average of 20 to 30 percent compared to other gas combinations, notably H35. The process also offers ISO Class 3 or better quality, preserves fast cutting speeds, and ultimately yields welds with an integrity that matches that of other cutting options (see tables)

According to the company, using nitrogen for the plasma gas provides a very straight cut with minimal cut lines and a narrow kerf. It also provides excellent electrode life and low-cost operation. Using water to generate the shield gas provides numerous additional benefits: it reduces dross, preserves the material’s mechanical properties, and prevents oxide formation.

At Chromalox, the nitrides and carbides present in other processes were unacceptable.

“We can’t weld over the cut surface if there is contamination from nitrides,” said Welding Engineer Christian Loya. “With the quality of the cut that we get from the WMS system, we just go over it once with light grit, and we’re ready to weld.”

About the Author
FMA Communications Inc.

Eric Lundin

2135 Point Blvd

Elgin, IL 60123

815-227-8262

Eric Lundin worked on The Tube & Pipe Journal from 2000 to 2022.