May/June 2003
Here’s what you need to know to select the right alligator shear and ensure that it’s operated safely.
By Jim Fowler
There was a time when alligator shears were “the common denominator of all scrap yards,” according to the 1954 book The Story of Scrap. While these basic, rugged machines—developed in England more than a century ago and initially called crocodile shears—have lost some of their prevalence, they remain workhorses of the scrap industry, especially for size-reduction and metal-cleaning tasks.
The challenge with alligator shears, however, is that the operator has traditionally had to work in close proximity to the most dangerous part of the machine—its moving blade. Unfortunately, this situation has resulted in innumerable amputations and even some deaths in the scrap industry over the years. Fortunately, today’s alligator shears offer enhanced protective features. Also, some processors have developed new approaches for operating these machines safely and productively.
This review looks at the safety aspects of alligator shears as well as the factors to consider when you’re in the market to buy one.
Guard the Machine or Guard the Worker
Mike Mattia, director of risk management for ISRI, receives a lot of safety-related calls from scrap processors, and the most frequent calls concern alligator shears. The question is always the same: “An OSHA inspector was just here and said I can’t operate my alligator shear without a guard. What do I do?”
As Mattia explains, the U.S. Occupational Safety & Health Administration (OSHA) does indeed have general machine-guarding standards that encompass alligator shears (29 CFR 1910.212). In essence, the OSHA machine-guarding standard gives companies a choice regarding alligator shears—either guard the machine or guard the worker.
To help processors understand this choice, ReMA has created a new video titled Working Safe and Smart With Shears as part of its Working Safe and Smart educational series. (A complimentary copy has been sent to each ReMA member company, while nonmembers can buy the video for $150.) The segment of the video on alligator shears describes verbally and visually four techniques to enhance the operator’s safety.
The first technique is simply to not operate an alligator shear unless it has a cage guard, which covers the upper moving jaw of the shear while still allowing the operator to feed material underneath. This guard prevents the operator from getting his hands too close to the cutting area and shields him from the upward movement of sheared scrap. All alligator shears sold today come equipped with such guards, which can be adjusted to accommodate various sizes of material.
“An alligator shear should not be operated without some form of guarding in place to protect the worker,” stresses Mattia.
Even though the number and severity of injuries from alligator shears each year are considered small when compared with all occupational injuries from industrial equipment—and though the number of alligator-shear fatalities is minuscule—the greatest concern is the “injury potential” of this equipment, Mattia points out.
As he explains, “Without a guard, the operator faces 100-percent danger and faces that danger a greater percentage of the time than, say, a baler or guillotine shear operator. The numbers don’t convey the danger, but it’s an accident waiting to happen—the possibility of injury skyrockets, and the worker is just one mistake away from losing a finger.” Unfortunately, he laments, this threat is “a hard concept to explain to someone who has been working an alligator shear for 20 years and never had a problem.”
To be sure, there are many operators who have used unguarded shears for decades and never had an accident. As a result, they don’t see the need for retrofitting a guard onto their machine. Their attitude is, “What’s the big deal?” The big deal is that an unguarded alligator shear is a safety violation.
In other cases, the first thing some operators do when a new shear arrives is remove the cage guard so the machine is “easier to operate.” As Mattia points out, “cage guards are good for sizing material, but aren’t that effective for cleaning metal. Operators grouse that metal cleaning is difficult with the cage in place—and it probably is.”
To prevent users from removing the cage guard, some manufacturers have designed the cage with a limit switch so the shear won’t operate if the cage is removed.
The other three techniques described in ISRI’s new shear video were developed by scrap processors, who are “ingenious about putting safeguards in their plants,” Mattia says. What’s more, OSHA has approved each of these techniques for use in scrap-shearing operations.
• Protective Cage: This technique encloses the entire shear—not just the blade—in a protective cage, preventing the operator from coming near the blade while allowing sufficient access to feed scrap (especially longer pieces for size reduction) into the shear. These totally enclosed shears have a holding bin under the cutting area to catch processed material and allow it to be safely removed.
• Two-Handed Controls: In this technique, a guard surrounds the cutting blade, and material to be cut is placed on an oversized infeed surface. The difference is that the operator can activate the cutting stroke only by depressing two buttons simultaneously. This ensures that both of the operator’s hands are safely away from the cutting area.
• Hand Restraints: This safety technique places the guard on the worker rather than the shear. Adjustable straps are attached to an elevated crossbar with O-rings that allow the straps to move from side to side. Restraints at the bottom of the straps are placed over the operator’s hands. These restraints give the operator free range of movement to areas away from the shear so he can easily grab material to be processed and do other tasks in the work area. Though the operator can easily feed scrap into the shear, the restraints stop his hands from moving under the shear blade.
The latter two methods—two-handed controls and hand restraints—are the safest ways to clean metal, Mattia says. If you want to use your alligator shear for metal cleaning and sizing, you’ll probably need two separate guarding techniques to accommodate each operation, he suggests, adding that “using hand restraints would be the exception.”
Aside from these safety measures, Mattia also recommends periodically checking the shear blades to ensure that they’re in proper working condition. Operating with old, worn blades can be a fatal mistake, he asserts, recounting the story of one scrap company that operated its shear with rusting, crumbling blades. “When the shear cut into scrap,” Mattia says, “it dislodged a long, sharp section of the rusting blade. This section was propelled into the operator’s abdomen and then pierced his heart. The operator died later that day.”
Other employees working nearby could likewise end up in harm’s way from flying pieces of scrap from the shear. It’s a good idea, therefore, to prevent all employees other than the shear operator from getting too close to the moving shear, Mattia says.
For him, the bottom line is straightforward: “If you don’t have a guard on your alligator shear, it’s an OSHA violation as well as a safety hazard. Even with careful, experienced operators and good luck, an accident is just a matter of time.”
Getting the Right Shear
The myriad safety concerns of alligator shears raise the question: Is there an alternative to using this equipment in scrap operations? The unanimous view is that there will always be a need for alligator shears, particularly for metal cleaning.
In the early 1970s, the Metal Scrap Research and Education Foundation—part of the Institute of Scrap Iron and Steel—conducted a census of equipment in U.S. scrap processing plants. It estimated that there were 2,100 alligator shears in use in 1974. By 1984, that number had declined to 650, according to a follow-up study. That number is too low, say alligator-shear manufacturers, who maintain that there are at least 3,000 to 4,000 alligator shears in use at U.S. scrap operations. One manufacturer claims it has sold some 2,000 units in the United States in the past 30 years.
Whatever the estimate, the number of alligator shears in operation today is significant—and more are being sold each year. Most manufacturers make a variety of models, some as many as eight and often with variations within models, with the main variables being blade length, cutting force, and horsepower. If you’re in the market for an alligator shear, there are a number of factors to consider, manufacturers note, including the following:
Material and Reason for Shearing: The kind of material you intend to shear and your reasons for shearing—metal cleaning, size reduction, or both—are critical issues, say manufacturers. Make a list of the different types of scrap you plan to shear—stainless, aluminum, steel, cable, tubing, sheet, plate—keeping in mind that the more precisely you define your scrap, the higher the likelihood of getting the right alligator shear for your needs. For example, if you plan to mainly cut 2-inch-round titanium scrap, you’d be wise to buy a larger machine capable of cutting 3-inch rounds—with cutting force from 80 to 180 tons—because of titanium’s hardness. For smaller scrap processors who want to shear all types of material, versatility in an alligator shear is important. If that’s your situation, make sure the manufacturer knows that when you’re shopping.
Blade Length: Alligator shears can come with blade lengths as small as 4 inches and as long as 36 inches. The length you choose will depend on the material being processed as well as the type of processing to be done. The manufacturer of an 8-inch model, for instance, says its shear is often used in conjunction with wire chopping lines to remove connectors from reels of cable. If you wish to use the shear to clean radiators, on the other hand, you should select a blade long enough so the operator can process the material in one cut rather than two. Similarly, processing aluminum doors in preparation for baling would dictate a longer shear blade while a smaller blade would suffice for sizing aluminum siding.
Manufacturers estimate that 75 to 85 percent of alligator shears in operation are used for metal cleaning, with the most popular shears having a blade length in the middle of the range. One manufacturer says its most popular shear has a 16-inch blade length, while another says 12- and 16-inch blades are the most popular in its line. Yet another claims that 26 inches is the ideal blade length for general-purpose metal-cleaning tasks.
Keep in mind that a longer blade doesn’t necessarily mean a stronger cut. One manufacturer notes that you’ll lose about 75 percent of the cutting strength at the outer end of the blade.
Shearing Force: Alligator shears can deliver cutting force ranging from 25 tons on the low end to more than 300 tons in larger models. If the shear will be used for metal cleaning, 30 to 80 tons of shearing force is adequate, say various manufacturers. The best advice is to be as specific as possible about the type and size of material you will be shearing, then select the model that best meets those needs.
Motor Size: The power of an alligator shear’s electric motor can vary from just a few horsepower to 100 hp. Horsepower determines the speed of the shear’s cutting cycle, not the cutting force, with the general rule being that the higher the horsepower, the faster the cycle.
While electric motors are the norm, gasoline and diesel engines are also available for recyclers who need to operate a shear in places where electricity is unavailable. According to one manufacturer, if the shear would use a 10-hp electric engine, the processor would need about an 18-hp gas or diesel engine to achieve the same performance.
Geometry of the Shear: The so-called geometry of the shear determines whether the cutting is done by the body of the machine or by the hydraulic system. On some shears, the hydraulic system reportedly does 90 percent of the cutting when, in fact, it should do little. Most of the cutting force should come from the geometry of the shear—the triangle determined by the distance from the top cylinder mount to the center of the pin (where the jaws join) and from the center of the pin to the back cylinder mount. The distance from the top cylinder mount to the pin determines the size of the triangle—and that’s the issue. For example, if the top cylinder is 12 inches from the pin, the cylinder is virtually horizontal. As a result, the hydraulic system is doing most of the cutting. When all of that force is put on the hydraulic system, the pumps and valves will fail prematurely.
In contrast, if the cylinder is 18 or 20 inches from the pin, more of an angle is created for the cylinder, which means that the geometry of the shear is doing the cutting. The body of the shear is making the cut, acting like a lever, with little dependence on the hydraulics. That saves the hydraulic system.
Bearing or Bronze Sleeve: One manufacturer recommends asking whether a shear has a bearing or a bronze sleeve inside the shear pivot point. This producer claims that a bearing is much better, explaining that you can get slack with a bronze sleeve that causes a spread in the shear arm when it comes down, which puts a strain on the sleeve. The shear does not cut nearly as well if there’s separation between the two blades as the arm comes down, the manufacturer states.
Parts Availability: U.S. alligator-shear manufacturers are quick to point out the ease of availability of replacement parts. One producer says that whether it’s a pump, valve, cylinder, hose, foot pedal, or electrical component, the part is available off the shelf from suppliers throughout the country. That means the user isn’t dependent on the manufacturer for parts.
Overseas manufacturers, meanwhile, stress that replacement parts are readily available through their U.S. representatives—and if they don’t have the part on the shelf, it can be quickly delivered.
Price: As you’d expect, the price range for alligator shears is rather broad—from about $4,000 to nearly $350,000—though many manufacturers say their most popular models cost between $10,000 and $25,000.
As you shop for your alligator shear, you’ll encounter special features offered by various manufacturers such as shear blades with four cutting edges rather than the more standard two; shears with a channel base for easy movement by forklift over rough ground; and shears with casters so they can be rolled to various inside locations.
Though the alligator shear is a “dinosaur,” as one manufacturer calls it, it won’t become extinct because it serves a purpose. Unfortunately, no manufacturer can guarantee that its alligator shears will be used safely while serving that purpose. As one producer asserts, “Every shear comes with a guard, but if we made it completely idiotproof, the machine wouldn’t function.” Scrap processors buying such shears must, therefore, factor safe operation into the equation, remembering that they basically have two choices—guard the machine or guard the worker. It’s as simple—and as complicated—as that.
Editor’s Note : For more information about OSHA’s machine-guarding standard (29 CFR 1910.212), visit www. osha.gov or call the Government Printing Office, 202/512-1800, or OSHA’s publication office, 202/693-1888. The National Safety Council also offers safety guidance on alligator shears in its data sheet #213. Contact the group at 630/775-2199. For more details about ISRI’s new Working Safe and Smart With Shears video, call 202/737-1770 or visit the Bookstore at www.isri.org.
Alligator Shear Manufacturers
MBH Bronneberg & Jegerings b.v. , 31/492-591900, www.bronneberg.nl
Deltax (represented by Gensco Equipment Inc.), 800/268-6797, 770/808-8711, or 416/465-7521, www.genscoequip.com
Enterprise Co. , 714/835-0541, www.enterpriseco.com
Lefort USA , 314/446-0255, www.lefort-usa.com
Logemann Brothers Co. , 414/445-3005
J. McIntyre Machinery Ltd. , (represented by Recycling Equipment Corp.), 215/721-6464, www.jmcintyre.co.uk , www.recyclingequipment.com
MOROS/North America, 888/589-1112 or 502/368-1661, www.moros.com
RamJet/Alert Engineering Co. Ltd. , (represented by Sweed Machinery Inc.), 800/888-1352 or 541/855-1512, www.sweed.com
Recycling Equipment Solutions , 330/920-1500
Rigby Machinery Inc. , 330/753-6673, www.rigbymachinery.com •
Jim Fowler is retired publisher and editorial director of Scrap.
Here’s what you need to know to select the right alligator shear and ensure that it’s operated safely.