Spectrum 1000 Plasma Cutter Saves Concrete Recycling Facility $52,000 Annually
Executive Summary
Miller Electric Mfg. Co.’s Spectrum 1000 plasma cutter offers Bedrock Stone, Inc. increased cutting speed and quality while offering a quick return-on-investment and continued savings:
- $52,000 savings annually in overhead costs versus an oxy-acetylene torch.
- Straight, more accurate cuts than with oxy-acetylene.
- Works well on a variety of materials: steel, aluminum, abrasion-resistant steels.
- Works well to cut and gouge out old wear plates and buckets.
- Miller’s Auto-Line™ technology ensures a steady cutting arc, produces a cleaner ending cut, lowers primary amperage draw and increases location flexibility.
- Spectrum 1000 paid for itself in savings within 1.3 months.
Spectrum 1000 Plasma Cutter Saves Concrete Recycling Facility $52,000 Annually
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Bedrock Stone, Inc. fabricator/welder Oswaldo Hernandes swears by Miller’s Spectrum 1000 plasma cutter for heavy-duty maintenance and fabrication applications.
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Ellen Fiore knows a good investment when she sees it. That’s why she located her company, Bedrock Stone, Inc., in the bustling Turnpike Corridor section of Kearny, NJ. As owner and president, Fiore grew Bedrock into one of the busiest Class B concrete recycling facilities in the region. Today, Bedrock recycles hundreds of incoming truckloads of brick, concrete, block, asphalt and dirt, which are used in road bases, foundations and construction sites. As another good investment, Bedrock recently acquired a Spectrum 1000 plasma cutter with Auto-Line® power management technology produced by Miller Electric Mfg. Co. and lowered equipment maintenance, repair and fabrication costs by $1,000 to $2,000 per week.
Preventative Measures
Bedrock is a high volume concrete recycling facility, sending out anywhere between 200 to 400 truckloads of finished products per day. To break down large pieces of concrete, Bedrock uses a dual impactor crushing machine that feeds incoming material through a pan feeder (see Figure 1), sends it to a rotating impactor, which then hurls large concrete blocks towrd a steel-lined apron. The tremendous force generated shatters large pieces of concrete into smaller ones. It also produces a lot of wear.
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| Figure 1: Bedrock Stone uses the Spectrum 1000 plasma cutter to fabricate liner plates and wear plates for the pan feeder (foreground) and crusher. |
For durability against highly abrasive concrete, Bedrock lines the impactors with abrasion-resistant steel plates. Due to the tremendous volume of concrete that Bedrock processes, the plates frequently wear out, as do the buckets, blades and teeth on the company’s 12 pieces of “yellow iron” (Komatsu excavators, bulldozers and front-end loader). As a result, Bedrock spends thousands of hours each year cutting plate, such as from steel grades AR400 and AR500, to specific shapes and welding it in place.
“We are pretty busy, and we need good equipment to keep up with demand,” comments Charlie Dolan, Bedrock operations manager. For that reason, Bedrock follows a carefully planned preventative maintenance program to ensure its equipment stays in top condition.
To lower maintenance costs and time, Bedrock first examined plasma cutting technology about two-and-a-half years ago as an alternative to its oxy-fuel cutting equipment. On 1/4- to 1-1/2-in. thick steel plate, Bedrock realized that a hand-held plasma cutter would improve its productivity by increasing cutting speed and quality and offering lightweight portability.
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| Figure 2: Moving concrete causes equipment to wear quickly, so Bedrock has implemented an aggressive preventative maintenance program to ensure equipment availability. |
Understanding Plasma
The plasma arc results from electrically heating a gas, typically air, to a very high temperature. This ionizes its atoms and enables them to conduct electricity. A plasma arc torch uses a “swirl ring” that spins the gas around an electrode. The gas is heated in the chamber between the electrode and torch tip, ionizing the gas and creating plasma. This causes the plasma gas to greatly expand in volume and pressure. The small, narrow opening of the torch tip constricts the plasma and accelerates it toward the work piece at very high speeds (20,000 ft./sec.) and temperatures (up to 30,000° F).
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Figure 3:The force of the arc from an 80-amp plasma cutter easily punches through 1-in. steel plate. |
The high-intensity plasma jet melts a very focused area. The force of the jet (or arc) pushes through the work piece and removes the molten metal (see Figure 3). This jet creates a clean, precise cut of narrow width, and easily allows an operator to trace around a template or cut specific shapes. The plasma jet easily cuts through metals with poor heat conductivity (stainless steel) or excellent conductivity (aluminum). The flame created by an oxy-fuel torch lacks this concentration, which is why oxy-fuel cuts stainless steel or aluminum so poorly.
The concentrated plasma jet also cuts steel very quickly. An 80-amp machine, a very common size for construction and heavy maintenance applications, typically has a rated cut of 1 in. This means that it cuts 1-in. thick steel at a rate of 10 inches per minute while producing a clean, attractive cut that needs little or no post-cut grinding (see Figure 4). More importantly, note that as metal thickness decreases, plasma cutting travel speeds increase. As shown in Figure 5, an 80-amp machine cuts 1/2-in. steel at about 50 inches per minute (IPM), and it cuts 1/4-in. steel at 120 IPM.
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Figure 4: An 80-amp plasma cutter, the Spectrum 1000, cut this 1-in. steel plate cleanly and with a straight edge. Note the lack of slag. |
Figure 5: This graph shows cutting speeds for the Spectrum 1000, an 80-amp plasma cutter. Notice the extremely fast cutting speeds on 1/4- and 1/2-in. plate. |
“We use our plasma cutter to cut replacement plates for our dual impactors, and these pieces have to be exact,” says Dolan. “By having the plasma cutter, we can cut a perfectly straight line, which you can’t do with a torch. In fact, maybe just one piece cut with a plasma may need to be realigned, and all the work will be done in a couple of hours. It used to take us a day or a day-and-a-half to cut all the plate for the impactor.”
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Figure 6: Using the Spectrum 1000, fabricators cut AR400 and AR500 abrasion-resistant plates to match the contours of excavator buckets and blades. |
Bedrock fabricators also cut wear liners that match the contours of excavator buckets and dozer blades (see Figure 6). To save time, Bedrock fabricators use templates and pre-cut several wear liners, which are stored in a central location. As the old liners wear down, welding operators use the plasma cutter to cut and gouge out the old plates and hard surfacing layers. The Spectrum 1000 works well for gouging because it produces an extremely long gouging arc, which helps in hard-to-reach, heavy applications like equipment maintenance.
In addition, Bedrock uses its plasma cutter to cut aluminum sheets to line its trailers. Bedrock uses the aluminum trailers for transporting wood and other materials around the facility. “The trailers are big, the sheets are long, so it’s easier to put down a straight edge as a guide and run the torch right along it,” Dolan adds. “We can cut through a 1/4-in. piece of aluminum in minutes. It’s a big time saver compared to a saw.”
Increased Productivity, Cost Savings
When Bedrock moved to plasma cutting, it did not initially purchase a Spectrum. While Bedrock saw the productivity advantages of plasma, its first plasma cutter caused headaches due to downtime.
“Operators would inadvertently touch the tip to the work piece. As a result, they would blow out the torch tip,” says Dolan. “Our guys were shutting down the machine and constantly changing out tips. You pay for manpower¾and that’s a huge cost plus I have to buy more tips.”
Bedrock’s welding supply distributor, Greg Wlazlowski of Welco-CGI Gas Technologies, adds that, “Bedrock also had problems with incoming line voltage. We checked incoming power with a voltage meter and found that at one point, the 230V, three-phase line only had 190V.”
Low voltage conditions resulted from summertime peak power demands, as well as a hidden wiring problem. “Whenever the voltage dropped, the competitive plasma cutter wouldn’t even initiate an arc,” says Wlazlowski.
Fortunately, Wlazlowski saw a chance to turn this problem into an opportunity for Bedrock to test the Auto-Line power management capabilities of the Spectrum 1000. As implemented in the Spectrum 1000, the Auto-Line circuit works by automatically connecting to any primary input voltage from 208 to 575V, single- or three-phase, 50 or 60 Hz. In addition, LVC™ line voltage compensation provides peak performance power under variable input voltage conditions, giving the Spectrum 1000 a total operating range of 176 to 630V. As long as incoming voltage stays within the 176 to 630V range, Auto-Line ensures a steady cutting arc. Auto-Line also produces a cleaner ending cut, lowers primary amperage draw and increases location flexibility.
“After Greg demonstrated the Spectrum 1000, we thought about it for 10 minutes and decided to go with it,” Dolan comments. “We haven’t had a problem yet. The Spectrum 1000 is a dynamite machine that just never shuts down.”
“I like cutting with the Miller machine much better. It cuts faster and it’s easier to use,” adds Bedrock fabricator/welder Oswaldo Hernandes (see Figure 7).
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| Figure 7: Bedrock fabricator/welder Oswaldo Hernandes reports that the Spectrum 1000 cuts faster and is easier to use than competitive machines |
One key to the Spectrum 1000’s ease-of-use is its Auto-Refire TechnologyÔ, which increases operator comfort by reducing hand fatigue. This technology automatically controls the pilot arc when cutting expanded metal or multiple pieces of metal. The pilot arc will switch on and off as fast as necessary (instead of the operator needing to re-trigger the torch), and it automatically provides maximum power for cutting thicker metal.
“It might not sound like a big deal, but if our guys are happy with the Spectrum, they use plasma more often than oxy-fuel when cutting,” says Dolan. “That saves time, and by saving time, it saves money.”
Bedrock employs four full-time fabricator/welders. When the fabricator/welders only used oxy-acetylene torches for cutting, overhead costs for the Bedrock’s maintenance shop averaged about $6,000 per week. After switching to plasma cutting and the Spectrum 1000, costs average $4,000 to $5,000 per week (costs vary based on work load). Using conservative accounting methods (see Figure 8), the Spectrum 1000 produced a return on investment of 925 percent and a payback time of 1.3 months.
“By using the Spectrum 1000 plasma cutter whenever possible, we can save at least $1,000 a week. That’s $52,000 a year,” says Dolan. “With four guys working on various projects in the shop, plasma easily saves us 10 hours a week or needing to pay overtime. There are certain jobs where we have to use oxy-fuel torches, but if we don’t have to use it, what are we doing? We are using electricity and shop air to cut. You can’t beat that for a low operating cost” (compared to buying compressed oxygen and acetylene).
Location Flexibility
While 80-amp plasma cutters sever steel plate up to 1-1/2 in., models that use inverter technology like the Spectrum 1000 also offer lightweight portability. The Spectrum 1000 weighs just 92 lbs. and has two carrying handles for convenience when moving it.
Bedrock’s crushing plant is about 1,000 ft. from the maintenance shop, and the fabricator/welders need to crawl inside the impactor to cut and gouge out the old plate.
“The portability of the Spectrum 1000 with that Auto-Line feature is fantastic,” says Dolan. “We have a 230V receptacle near the impactor, so fabricator/welders can actually just run an extension cord from that and set the plasma cutter right down next to where they’re working.” Dolan also notes that it’s much easier to run an air hose from a compressor than it is to move up to 200 ft. of oxy-fuel torch hoses.
If Bedrock isn’t using the Spectrum 1000 at the concrete recycling facility, it gets used at Bedrock Quarry Materials in nearby Landing, NJ. The Spectrum 1000’s Ultra-Quick Connect system offers fast and easy torch connection and disconnection. This helps when moving the unit, as dragging a 25-ft. cutting torch along with the unit can be cumbersome.
“Our guys just throw the Spectrum 1000 in the pick-up truck and take it to the quarry,” says Dolan. “That plant’s big. It’s on 180 acres of land. But as long as there’s electric power, we’re working with the Spectrum 1000, and it works well.”
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