Author: Phil Parker, Marketing Manager, Mechanized Plasma Systems, Hypertherm
Several types of metal cutting solutions exist in the market today, such as plasma, laser, waterjet, oxyfuel and a variety of mechanical means. While all of the cutting processes mentioned are well-established with a good track record, each has benefits and shortcomings that need to be considered when deciding on a cutting method.
In Asia, plasma is fast-becoming one of the more popular choices for modern manufacturers, especially when it comes to fabrication of metals that may not provide optimal results when used with traditional cutting methods. Not only does plasma provide a good balance in terms of capital cost and an optimal mix of cut quality, it also offers high cut speeds and is highly versatile.
So, what is plasma? Simply put, plasma cutting is a technology that uses a high temperature ionized gas to produce a very hot, high energy-density arc that can cut any electrically conductive material. The plasma stream is typically formed by forcing such gases as nitrogen, oxygen, a mix including argon, hydrogen and nitrogen — or even air — through a narrow nozzle, while an electric current produced by an external power supply adds sufficient energy to the gas flow to ionize it, turning it into a plasma arc with temperatures that can approach 40,000˚F. The plasma arc then melts and severs the metal. This is the principal process for both handheld and mechanized plasma cutting systems.
The Plasma Advantage
Hypertherm’s Powermax 85 air plasma cutting system.
Where metal cutting is concerned, several factors affect efficiency, with a critical one being cutting speed. In manufacturing, this is especially important as it would mean that jobs get completed in a shorter time, leading to an increase in overall productivity. Compared to other processes, plasma cuts at the fastest rate and is the most productive when cutting metals that are greater than 6mm (1/4″) but less than 76mm (3″), due to the fact that the plasma arc is able to melt the metal almost instantly upon contact. Cutting speeds also increase as metal thickness decreases, and this increased speed means that operators can cut more parts in less time.
Cut quality is also another critical consideration for companies when it comes to selecting their metal cutting equipment. Plasma cutting, particularly high performance plasma is capable of producing edges that are relatively smooth with very little edge hardening, which makes for excellent weldability. Furthermore, it produces minimal dross, reducing the need for secondary processes like grinding. Overall, plasma produces high quality cuts that are cleaner and more precise when compared to oxyfuel.
In recent years, ease-of-use of technical processes has also been gaining importance as a key decision factor in Asia when it comes to technological investments, primarily because it minimizes training, improves safety, and ultimately increases profitability. Coupled with the latest technology CNC and software, plasma is extremely easy to learn and use with preset parameters embedded in the accompanying CAM software, minimizing the need for operator expertise. In addition, handheld plasma cutting systems are highly portable due to their relatively compact size and light weight.
Yet another advantage of plasma cutting is its versatility. As plasma cutting employs a high-temperature, electrically conductive gas arc to cut through any material that conducts electricity, it can be used on ferrous and non-ferrous materials, and on metal that is in any condition – even rusted, painted, or grated. This confers a higher degree of flexibility to the cutting job as plasma can cut a wider range of metal types and thicknesses. Even within the cutting process, the versatility of plasma systems is further expanded when used in combination with specialized torches and consumables. Many torch options are now available in the market, varying in lengths and torch head angles that cater to different industrial needs and applications. Plasma can also be used for drag cutting, standoff cutting (particularly useful when cutting odd-shaped pieces, or when trying to access a tight location) and even for getting high quality, very narrow cuts on thin materials, simply by replacing the consumable parts on a torch. This is an attractive feature as a single plasma cutting system can be employed in a variety of applications with a simple change of the torch and/or consumables, without having to switch back and forth among various tools.
Apart from cutting, plasma systems can also effectively carry out alternate applications at the same time. One example is gouging, and typical applications of it include the removal of an existing weld during repair work, scrapping or dismantling, as well as “back-gouging”, the process of removing the slag layer for multiple-layer welds. Plasma cutting is therefore capable of satisfying the cutting and gouging needs for a broad spectrum of industries, whether for thin or thick, ferrous or non-ferrous metals.
Plasma can also be used to mark materials, either with alpha-numerics to identify parts or to lay in weld lines. Modern automated systems allow you to cut and mark using the same consumables, considerably enhancing productivity.
As illustrated above, plasma provides an optimal mix of cut quality, productivity, convenience, and versatility for mild steel, stainless steel, and aluminum across a wide range of thicknesses. Existing plasma systems are already considered competent in their own right, but manufacturers have in recent years increasingly sought more advanced means of cutting in their pursuit for higher efficiency and better results. Coupled with the advent of technology, there now exists a growing demand for more developed and sophisticated cutting systems that can better meet the needs of modern manufacturing.
With that in mind, Hypertherm recently launched its latest mechanized plasma cutting system – the XPR300TM.
Meet the New Plasma
The first of its kind, the XPR300 represents the most significant advance in mechanized plasma cutting technology ever. Compared to its predecessor – the industry leading HPRXD®line- the new system exhibits a leap in cutting performance and cost-effectiveness. It offers unrivaled cut quality on several metals (e.g. mild steel, stainless steel, and aluminum), increased cut speed, improved productivity, and a 50% reduction in operating costs. In addition, newly introduced ease-of-use features and engineered system optimization make the XPR300 easier to run with minimal operator intervention, while also ensuring optimal performance and reliability.
These advances are attributed to an array of new process technologies, which Hypertherm has branded as X-Definition™ cutting (see Table 1).
Enhanced Productivity & Profitability
To most metal fabricators, there are two key benefits that they seek from their plasma cutting equipment: improved performance and better cost-effectiveness. These are the main areas that Hypertherm seeks to address with the introduction of the XPR300.
When it comes to industrial cutting, productivity and profitability, or a lack thereof, can come down to a few things – Cut Speed, Cut Quality, Consumables Life and System Uptime. The XPR300 addresses all four aspects by creating a system that cuts faster, cuts better, and more efficiently using “smart” technology and time-saving steps.
Cut Speed – by having 300 amps and 63 kilowatts of power, as compared to the 260 amps and 45.5 kilowatts offered by its predecessor, the XPR300 is able to cut faster. The exact speed increase is dependent on the material thickness, but users can generally expect a 10 to 20% increase on materials between 15 and 40 mm in thickness, 38% increase on 50 mm materials, and nearly 50% increase when cutting 60 mm thick materials. Such improvements in cut speeds translate to increased productivity and profitability since one can complete more jobs with the same amount of time.
|Thickness||Cut Speed (mm/min)|
XPR300 cuts at 10 to 20% faster than its predecessor on metals up to 40 mm thick, and nearly 50% faster for materials thicker than 50 mm (2″).
In addition to faster cutting speeds, the XPR is more efficient than the HPR260XD®. For instance, the XPR300 only requires 170 amps to meet the cutting speed of a HPR260XD system at 200 amps. Not only does it allow faster cutting, the XPR consumes less energy in the process as well.
The cut speed of a XPR set at 170 amps is comparable to that of an HPR using 200 amps of output current.
Cut Quality – the differentiating factor lies in Hypertherm’s proprietary X-Definition cutting that further enhances plasma’s ability to tackle high precision applications. This class of cutting improves cut quality as measured using ISO 9013, an international standard that defines the quality of thermally cut parts. This standard uses a scale of 1 to 5, with a Range 1 cut considered best. The new XPR300 provides ISO Range 3 cut quality for nearly the entire lifespan of the consumables, and its cut quality on thin mild steel is consistently within ISO Range 2. In comparison, Hypertherm’s HPRXD systems tend to provide Range 4 cut quality.
XPR300 300A mild steel process remains in ISO Range 3 for nearly its entire process life of 1,368 20-second cuts on 20 mm (3/4″) plate, compared to ISO Range 4 for its predecessor (HPRXD).
XPR300 80A mild steel process remains in ISO Range 2 for roughly 1,300 20-second cuts on 6 mm (1/4″) plate, before moving into ISO Range 3.
In addition to improved cut quality, the other noteworthy aspect is the consistency of the cut. The XPR can produce parts with uniform cut quality, the result of several new technologies. One of those processes, the patent-pending Vented Water Injection™ (VWI), combines a nitrogen plasma gas with a water shield to better align and focus the plasma arc. A second, called Vent-to-Shield, reclaims hydrogen from the vented plasma gas and mixes it with the shield gas. Together, these two technologies produce squarer cut edges with less angularity, and an improved surface finish when compared to the HPRXD systems. The XPR also utilizes a process called Advanced Arc Stability designed to stabilize the plasma arc, as well as new segmentation protocols for holes that surpass Hypertherm’s existing industry-leading True Hole® process on HPRXD systems. This enables the XPR300 to easily fabricate bolt-ready holes down to a diameter-to-thickness ratios of 1:1. As cut quality improves, it may be possible for fabricators to perform more cutting jobs in-house, without having to outsource these jobs to laser and other specialized cutting centers. This can lead to significant cost savings, an improved and more efficient supply chain, faster delivery of jobs, and greater overall profitability.
Consumables Life–The XPR is equipped with a patent-pending feature called Cool Nozzle™, which provides liquid
cooling directly to the nozzle bore, increasing consumable life. During laboratory testing for instance, it was found that XPR consumables can make close to 1,400 twenty-second cuts on 18mm (3/4″) mild steel, which represents 50% improvement. The increased consumable life is further enhanced through the new Arc Response TechnologyTM, consisting Automatic Torch Protection and Automatic Ramp-down Error Protection features.
In cutting, ramp-down errors are considered very damaging to consumables. These errors occur when an arc is terminated in an uncontrolled manner by running off the plate or by having an interior feature (like a hole or slot) fall away. When this happens the hafnium emitter located at the tip of electrodes used in cutting mild steel is unable to resolidify when an arc “snaps” off . As a result, every time a ramp-down occurs, a little bit of hafnium is ejected from the electrode, accelerating consumable wear.
The XPR300 power supply addresses this issue through the Automatic Ramp-down Error Protection feature, in which the system senses when a ramp-down error is about to occur and rapidly terminates the arc in a controlled manner, enabling the hafnium to re-solidify and greatly prolong electrode and nozzle life. While most plasma systems experience approximately 50% reduction in consumable life from ramp-down errors, with the XPR300 the rate is reduced to less than 10%. This equates to a realized consumable life benefit that is nearly three times longer than usual, which also means more savings for the end customer.
System uptime – improvements to consumable life as mentioned before also contributes to system uptime. The patented PowerPierce® technology sends liquid cooling to the shield, which helps to repel molten metal during piercing, thereby preventing the shield from damage. With less time spent changing consumables, operators gain more time for cutting and for other value driven activities.
The XPR300 is one of the smartest mechanized plasma cutting systems to date. On-board sensors continually monitor current, pressure, temperature, and flow and compare to specifications during operation to ensure optimum uptime.
With a combination of faster cut speeds, improved cut quality, longer consumable life, and greater system uptime, the XPR results in greater productivity and profitability.
Cutting costs comparison between XPR300 and its predecessor.
In spite of the sheer volume of technology found in the XPR300, the system is surprising uncomplicated and user-friendly. Sensors in the power supply deliver refined diagnostic codes and significantly enhanced system monitoring information. This reduces troubleshooting time and provides proactive data for improved overall system optimization.
In addition to automatic system monitoring, the XPR contains several other features that redefine ease-of-use. For one, the system is designed with fewer consoles and connections so operators can spend less time setting-up and more time cutting. Other notable features include a connection device called EasyConnect™, which allows an operator to quickly plug the torch lead into the torch console without the use of tools,and a patent-pending QuickLock™ electrode that delivers easy ¼ turn tightening which further reduces job setup time and enables an operator to rapidly change a torch using just one hand.
The new XPR300 also includes built-in Wi-Fi capability into its power supply. Owners and operators can make use of this feature to monitor the system or perform process set-up tasks from a phone, tablet, or other portable devices. The Wi-Fi can also connect to the LAN for multiple systems tracking. Significantly, the XPR300 system supports Industry 4.0.
As illustrated above, Hypertherm’s XPR represents the next generation of industry-leading mechanized plasma cutting systems. With a combination of technology innovation and smart design, this new generation plasma system offers the highest standard for performance on mild steel, stainless steel, and aluminum, expanding cutting capabilities in ways that was not possible before.