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Clean cutting

New consumables offer long life in automated plasma cutting systems

Plasma cutting is one of the most efficient ways to cut sheet metal and heavy plate. A good plasma cutting system can save a shop hours of downtime and thousands of dollars in operating expenses. Part of what makes a good plasma system is using consumables that provide long life.

In late 2018, the U.S. Patent and Trademark Office issued a patent to American Torch Tip Co. (ATTC) for its unique CleanCut nozzle technology. The new technology, consisting of the nozzle and electrode, is making its mark on the industry by offering incredible consumable life for automated plasma cutting.

CleanCut nozzles have a smooth-bore configuration that reduces plasma arc turbulence. By pressurizing and accelerating the cut gas in a high-velocity configuration, ultra-smooth gas flow achieved.

“CleanCut’s nozzle design pressurizes the flow of gas, which constricts the stream and speeds up the gas,” says Matt Merrill, ATTC’s engineering director. “Once the pressure is released, it provides a more narrow, stable plasma arc. It is the only dual parabola design on the market.

The CleanCut nozzle provides faster cutting times and quicker piercing times for thicker materials. It also eliminates bottom dross and reduces bevel angle.

“The nozzle design provides better control of the cut gas, which gives our customers the smallest bevel angle possible,” Merrill says.

Some CleanCut nozzles also have tri-cooling fins that allow for 200 percent more surface area to be exposed to coolant, which helps extend the life of the consumables.

“A lot of older plasma machines are high-amp systems that are going to get hot,” Merrill says. “If you can increase the surface area, where the coolant is actually touching the nozzle, it keeps it cooler.”

The electrode

The CleanCut electrodes also play a part in extending consumable life. One differentiator of the CleanCut electrodes versus competitors is the composition of the electrode and how ATTC presses the hafnium, which is all proprietary information.

A second differentiator is that CleanCut copper electrodes are tipped with silver. This helps the plasma consumables run cooler because silver has a higher thermal conductivity rate than copper and dissipates heat faster.

“The active cooling on the front end of the consumable is the main attribute of the silver,” Merrill says. “Other competitors also offer silver-tipped electrodes, but the amount of silver we use and the way we apply it to the copper is unique. The silver is protecting that hafnium from burning the copper. With copper-only electrodes, the hafnium might typically burn up to say 1 mm and then start wearing away at the copper. The CleanCut electrode can go to about 2 mm with no problems before the copper starts to wear. That is why we see that increase in electrode life, which provides longer life for the other consumables.”

ATTC backs up the results the life of its consumables with its program that guarantees cost savings of 25 percent.

“We can save you 25 percent on your overall consumable spend, not just through the cost of the product but through the increased longevity, too,” says Jordan Norris, digital marketing director, ATTC. “While it’s true that everyone provides a guarantee of some kind, we literally can guarantee a 25 percent cost savings with these consumables. We do that through documentation. We track and record the performance of our CleanCut products against OEM parts, and provide definitive ROI improvement based on consumable cost and process improvements including training and education to equal 25 percent cost savings.”

Part of ATTC’s services is determining if the consumables are even the cause of a customer’s headache. “When a customer calls with an issue that they haven’t seen before,” Merrill says, “we send out techs that check all variables, from the last time the coolant was changed to contactors needing to be swapped out to having a solenoid sticking. We help them determine if it is a consumables problem, torch problem, gantry problem, or maybe something with the table or the power supply.

“The majority of the time, it doesn’t have much to do with the consumable or the torch,” he adds. “Although customers are quick to assume it’s the consumables, there is usually something else going on.”

CleanCut copper electrodes are tipped with silver, which helps plasma consumables run cooler.

Make the change

No matter the brand, eventually all consumables need to be changed. Signs that it is time include when the operator starts to see increased bevel or increased top or bottom spatter. Another sign is getting too much dross on the bottom of the cut.

To tell if an electrode is spent, inspect the hafnium dimple found in the center. A used electrode has a small pit caused by evaporation of the hafnium during cutting. Copper electrodes with pit depths between 0.045 in. and 0.050 in. are at the end of their life and need to be changed before they can cause catastrophic failure where the arc is actually burning through the opper. If this occurs, it causes additional damage to the nozzle and the shield. CleanCut electrodes can be used to a pit depth of 0.090 in. before requiring replacement.

The efficiency of plasma cutting can quickly be lost without proper consumable maintenance. To ensure the highest performance, operators must regularly inspect and maintain consumable parts. Using severely worn consumables can cause expensive torch failures and unnecessary downtime, and they can ruin a good piece of metal.

“It doesn’t happen often, but if you aren’t monitoring the consumables or if you’re pushing them too far, you can get a catastrophic failure,” Merrill says. “The electrode will take out the nozzle and the shield and maybe even the retaining cap. Once the hafnium is burnt out, there is really no way to focus the arc weld and the electrode is gone.”

Changing out the electrode too soon can also affect downtime and costs as the customer isn’t getting its money’s worth. Therefore, keeping close track of electrode life and changing it before failure can prolong nozzle life and the rest of the consumables.

“A lot of the smaller shops wait until they actually see a problem but many of the larger plants we do business with have Six Sigma black belts,” Merrill says. “They perform tests to determine how long each consumable lasts and develop a change-out interval schedule for their operators. This proactive approach to consumable life maximizes costs and uptime, while greatly reducing the chance of a failure.”

The CleanCut nozzle design pressurizes the flow of gas, which constricts the stream and speeds up the gas. Once the pressure is released, it provides a more narrow, stable plasma arc.

It’s important to ATTC to ensure its customers’ plasma operators are trained properly. To do so, the company sends out techs to train new customers and customers with new hires.

“We go through plasma cutting with them step by step,” Merrill says. “Many times, there is not a lot of time spent educating the operators working the plasma tables, so we like to make sure they really understand what is going on with that system when they use it.”

Future plans for ATTC include building on the CleanCut system by adding a CleanCut shield, as well. Asked if ATTC also sees areas for improvements in the caps and swirl rings, Merrill quips, “always.”

American Torch Tip Co.

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