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Welding Processes
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Welding Benefits
- Reduced welding costs
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- Improved weld quality
Plasma Cutter Operation
For cutting, begin by placing the torch as close as possible to the edge of the base metal. Press the trigger to initiate the pre-flow air; the pilot arc will then light, followed by the cutting arc. Once the cutting arc starts, move the torch slowly across the metal. Adjust your speed so that the cutting sparks emerge from the bottom of the metal. You should be able to see the bottom of the workpiece and the arc should be directed straight down. If the sparks are not visible at the bottom of the plate, you have not penetrated the metal. This is because your travel speed is too fast, you have insufficient amperage, or the plasma stream is directed at an angle.
At the end of a cut, angle the torch slightly towards the far edge of the metal or pause briefly to completely finish the cut. The post-flow air will continue for a short period of time after the trigger is released to cool the torch and consumable parts, however cutting can be resumed immediately.
To pierce or create a hole, begin with the torch at a 40-degree angle to the workpiece and press the trigger. When the cutting arc is initiated bring the torch tip to a 90-degree angle and the arc will pierce the base metal. A good rule to follow is that you can pierce up to one-half of the maximum cutting thickness provided by the machine.
Plasma arc gouging can be accomplished by replacing the cutting tip with a gouging tip, then placing the torch at approximately a 40-degree angle to the base metal. Press the trigger for the pre-flow air and pilot arc. When the cutting arc ignites, form the arc a short distance from the workpiece. Further adjust the arc length and travel speed as needed. Do not gouge too deeply, as several passes may be needed to accomplish the necessary gouge. Again, after releasing the trigger, the post-flow air will continue for a short period of time, but gouging can be resumed immediately.
Spectrum 1000 Takes Plasma Cutting to New Heights
Stratosphere maintenance crew cuts time in half
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| About 900 feet above the Las Vegas Strip, Brian Day uses a Miller Spectrum 1000 plasma cutter to cut apart the Stratosphere's High Roller roller coaster |
About 900 feet above the Strip, Brian Day pauses for a moment and looks down on the early morning Las Vegas skyline.
"I put up the signs there and there," Day says, pointing at the brightly lit casino signs below. The Strip casinos all look small from the top of the Stratosphere. Ready to start, Day picks up the torch to a Miller Spectrum 1000 plasma cutter and begins cutting another section off of the High Roller, the Stratosphere's famous roller coaster.
After 10 years and almost 3,000,000 riders, the High Roller's time has come. Although it was lifted into place by the Tower crane, its more than 110,000 lbs. of track will be going down in the elevator, one piece at a time. Day is one member of the ride maintenance crew who will be doing the demolition work under the direction of Patrick Brinckerhoff, the Stratosphere's director of ride engineering.
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Each section of track consists of three rails, varying in thickness from 1/4 in. to 5/8 in. After being cut, they are loaded onto a cart and taken down in the Tower's elevator. |
To fit into the Tower's elevator, the track and support structure needs be cut into approximately 367 three-foot lengths, each weighing about 300 lbs. To ensure safety—his primary concern—and speed—his people are working overtime—Brinckerhoff armed his crew with a Spectrum 1000 plasma cutter. The Spectrum 1000, with its ability to slice through a section of track in less than half the time of a gas torch, also eliminates the safety and portability issues associated with oxy-fuel.
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| Each 3-ft., 300 lb. section of track is taken down the Stratosphere's elevator and stored across the street. |
To see how much time he would save, Brinckerhoff conducted his own cutting speed test, pitting the Spectrum 1000 against the gas torch. He had one of his trained welders practice with the gas torch and then timed him. Cutting a section of track took between seven and eight minutes, although the operator felt that he could bring it down to below seven minutes with practice.
Then he tried the Spectrum 1000. The same cut took three minutes, ten seconds.
"Everyone is working on overtime, so the ability to cut the time in half is huge," says Brinckerhoff. With 367 sections to cut, the cutting times would amount to 19 hours for the Spectrum 1000 vs. 43 hours for oxy-fuel—a savings of 55 percent.
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"The ability to cut the time in half is huge," says Pat Brinckerhoff,whose crew is working on overtime to bring down the High Roller. The Spectrum 1000 saves 55 percent over oxy-fuel cutting. "It's already more than paid for itself. |
Fifteen days and already one-third of the way through the project, Brinckerhoff says, "The Spectrum 1000 has already more than paid for itself."
High Roller No More
Rising 1,149 feet above the Las Vegas Strip, the Stratosphere Tower is the tallest free-standing observation Tower in the United States and the tallest building west of the Mississippi River. Offering a breathtaking view of Las Vegas and the surrounding valley, the Stratosphere also offers some thrill rides for its more adventurous visitors. Three rides, the Big Shot, Insanity and X Scream, offer all the excitement of an amusement park with the added attraction of being one-fifth of a mile above ground.
While these rides spin, turn, hang passengers over the side or shoot them upward at high speed, the High Roller circled the observation deck at a mild 30 miles per hour. Many considered it the tamest of the rides. Like the Big Shot, which shoots its riders to the 1,050-ft. level, the High Roller has been with the Stratosphere since the beginning, lifted into place by the Tower's crane during construction. After 10 years, it needed rehabilitation and a decision had to be made.
"The High Roller was due for a facelift that would cost $100,000 to $200,000," Brinckerhoff explained. "The hydraulics were antiquated and it required a lot of maintenance to keep it in perfect working order. Even with the overhaul, it still wouldn't be as popular as our other rides. We decided instead to bring it down and look at possibilities for a future project to replace it."
To accomplish this, Brinckerhoff worked with an engineering firm, Interactive Rides, to engineer a Thern davit crane to the original front car frame of the roller coaster. The car is pushed into place, the crane is attached above the next section to be removed and the section is then cut away. Each 3-ft. length of track consists of one backbone, two running rails and a few track ties. The cutout section components range in thickness from 1/4 in. to 5/8 in. Once cut, the section is then hoisted onto a cart, taken down by elevator and placed into a storage yard.
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| The davit crane created to hoist the track sections out of the way. |
The same people responsible for ride maintenance during operating hours are doing the work. All 11 of them have electrical, hydraulic and mechanical backgrounds. Most of them have some welding experience; three are certified welders. Some are ex-military, others have put up the huge signs that light Las Vegas casinos or have worked at other theme parks. All of them are "accustomed to working at great heights," according to Brinckerhoff.
Several times a month, four or five crew members work overtime on the High Roller between 2 a.m. and 8 a.m., the only time the Tower isn't open to visitors.
The Right Tool For The Job
Before the demolition began, Brinckerhoff researched his equipment options. He called other amusement parks and spoke to others in the industry to see what they recommended. He then checked all of the top manufacturers' Web sites, landing at MillerWelds.com.
"When you're talking to others to do research, you get 100 different answers." Brinckerhoff says. "But the Miller Web site has been real helpful in putting it together. It has numerous case studies that show exactly what other people have done. It allowed me to associate products with what I need to do."
After conducting his research, he settled on a Miller Electric Spectrum 1000 plasma cutter. Rated for 1-in. (based on a cutting speed of 10 inches per minute) cutting capability and with features such as Auto-Line that allow it to connect to any primary voltage, from 208 to 575 volts, single- or three phase, the Spectrum 1000 seemed ideal for the job. Brinckerhoff called John Aldrich at Nevada Compressed Gas who agreed with his choice.
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Patrick Brinkerhoff, the Stratosphere's director of ride engineering, did thorough research before choosing the Spectrum 1000. One-third of the way through the project, he "couldn't be happier" with his choice. |
"There were several contributing factors to Patrick's decision, but the two most important were cutting speed and fire safety," Aldrich says. "The Spectrum 1000 met his needs in both categories."
Safety
"We have all of the concerns of any amusement park, but we have them 1,000 feet in the air," says Brinckerhoff, who is responsible for the rides' interface with the building. "When it comes to the safety of the passengers or the Tower, we don't make compromises."
Although he had an oxy-fuel cutting setup on hand, it presented several risks.
"One of my biggest fears is that if an acetylene tank were to leak, it would seriously compromise the integrity of our building," Brinckerhoff says. "Fire is probably the biggest concern, especially in a Tower. We can't store the oxy-acetylene tanks in the Tower because of fire department regulations. So the oxy-fuel tanks would have to be transported by elevators every night. We brought the Spectrum 1000 up and it stayed there. It really saves a lot of time and effort."
The Spectrum 1000 required very little in the way of safety training. The only safety concerns the operators have are those normally associated with arc welding. "'Don't become part of the circuit; wear the proper safety equipment'(a few simple rules," Brinckerhoff said. "We discussed safety and everyone read the manual."
Speed and Training
"Oxy-fuel cutting requires more skill," says Brinckerhoff. "If you have someone who is really skilled with a gas torch, you may be able to forgo the use of a plasma cutter. But if you have an operation like mine, where you have multiple users with different skill levels and backgrounds, the Spectrum 1000 is the way to go. We were productive right away. It's a very easy machine to use."
It also eliminated some of the difficulties a gas torch would have encountered.
"It's more difficult to use a gas torch on continuous round shapes and tubular sections," Brinckerhoff says. "One of the big differences is that with gas you have to get the area cherry red first in order to penetrate through and start the cut, and that is time consuming. You may run across inside plates that will also slow you down so you have to be more precise with cutting location. The Spectrum 1000 penetrates fast and just slices through."
At three minutes cutting time per section, they can rig and remove seven or eight sections of track per night. After 15 nights of cutting they have removed about 40,000 lbs, about a third of the total.
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| The results after 15 nights of cutting. Using the Spectrum 1000, each section of the High Roller track took about three minutes to cut. Using oxy-fuel would take seven minutes for each section. With about 367 sections, the time difference is 19 vs. 43 hours of cutting time. |
"It's more than paid for itself," Brinckerhoff says. "For pure power cutting, nothing beats the Spectrum," Brinckerhoff says. "It really is the machine to use. All of the major obstacles in using oxy-fuel(cutting speed, ease of use, transportation and storage of gas( were overcome by plugging the Spectrum 1000 into a 250V outlet."
Once the High Roller project is done, the Spectrum 1000 will still have plenty to do. "It's a great tool to have in our lineup of equipment," Brinckerhoff says. "We have to do some custom fabrication. We'll modify the plasma cutter to be used with a jig table set up."
The Spectrum 1000 will join a Millermatic 130 MIG welder, a Millermatic Passport welder and an XMT CC/CV multi-process inverter power source. Although Brinckerhoff is free to choose whatever product or distributor he likes, he keeps returning to Miller.
"We're not a weld shop," Brinckerhoff says, "Welding is only a part of our job. We see a job that needs to be done and then find products that can fill that role. All of our welding equipment is Miller."
