Equipment Focus: Guillotine Shears

Safety is a major concern when operating and maintaining these big cutting machines. Learn what processors and manufacturers are doing to make them safer—and more productive.

By Jim Fowler

Guillotine shears are among the biggest, most powerful—and, hence, most potentially dangerous—pieces of equipment in a scrap processing plant. The good news is that these shears account for relatively few accidents in the scrap industry. The bad news is that when an accident does occur, it’s usually fatal. Fortunately, processors have developed procedures that make life safer for employees who work around and maintain guillotine shears. Safe shearing operations are certainly achievable if management and employees are committed to that goal, veteran shear operators suggest. In their view, awareness is the key, along with a healthy dose of common sense.
   Procedures to eliminate shear accidents generally focus on two areas—operations and maintenance. In addition, equipment manufacturers continue to work hard to design and build safer machines.

Operations: Inspecting, Deflecting, and Elevating
Inspection of incoming scrap is a critical first step. Though inbound loads of scrap are usually inspected at the scale, even the best inspector can’t see what’s on the bottom.
   That’s why one Midwest processor has three dumping lanes at his shear site. After a load is dumped, the foreman conducts a walk-around inspection of the material. His main concern is closed containers, and he follows one simple rule: “If you can’t see inside it, you don’t shear it.” 
   Any pressurized enclosed container can explode like a missile in the shear head, and the resulting projectile can be lethal. At this Midwest processor, if the shear operator sees something suspicious, he stops the shear and calls the foreman to inspect the material. The operations manager views this approach as “a team effort in safety and productivity,” stressing that “you have to know your customers and what they’re shipping to you.”
   Falling scrap poses another safety concern. A Mid-Atlantic processor says no one should be in the vicinity of the shear while it’s being loaded. “Scrap may fall from the crane during loading, or material may fall from the sides of the machine if it’s overloaded,” he says. “The shear operator must be aware of where everyone is around the shear.” 
One way to accomplish this is with closed-circuit television cameras, which can monitor activity at critical points around the shear, especially employees in the sorting area.
   Shrapnel—material that flies out of the shear during processing—is one of the greatest safety concerns for shear operators. Probably half of the 12 shear fatalities in U.S. scrap plants in the past 10 years involved shrapnel hitting an employee in a sorting area, says Mike Mattia, ISRI’s director of risk management. Though ductile material is easily compressed and cut, brittle material such as cast iron and rebar resists the shear’s cutting force until a chunk of material is torn away. The force of that tearing process can propel a piece of scrap toward workers in the area. Other types of scrap—such as spring steel, shock absorbers, and hydraulic valve bodies—can also pose problems when cut. 
   That’s why a steel-plate scrap guard at the front of the shear is a must, says one shear manufacturer, noting that such a guard will catch 99 percent of shrapnel. Indeed, many shears have a deflection panel directly at the mouth of the shear that follows the up-and-down path of the shear, releasing metal after it has been cut. Also, a discharge chute lowers as the metal is cut, providing a flat deflection surface. A chain guard or curtain will also work if it’s properly maintained, which means no missing lengths and no gaps, say shear experts.
   Regardless of the type of guard, the critical point is to put a barrier between the sorting table and the front of the shear.
   Another safety issue is the potential for scrap to ricochet, which makes any worker in the area a potential target. “Any opening is enough for shrapnel to get through and hit an employee,” warns Mattia. So shear operators must search for all possible “strike paths” and identify “where you need guards and barriers to protect your sorters and nearby workers,” he says.
   This search can help determine what combination of deflection surfaces will provide a “safety zone” for workers in the strike path. Moving workers away from a likely strike path can provide additional protection. And, of course, make sure that any worker near a strike path is wearing a hard hat and safety glasses at all times. 
   The concept of safety zones—any area outside a strike path—is explored in ISRI’s video titled Working Safe and Smart With Shears. The video suggests a three-step approach for processors who operate guillotine shears:
• Determine the safety zone for workers, realizing that shrapnel could be released at any time.
• Determine the possible ricochet paths based on the position of deflection surfaces.
• Determine various locations where a worker could be struck by deflected shrapnel.
   With this information, the processor can decide what combination of deflection surfaces will provide a safety zone for workers in a strike path. (ISRI sent a complimentary copy of Working Safe and Smart With Shears to every member company. Members can buy additional copies for $75 each. Nonmembers can purchase the video for $150 by calling 202/737-1770 or visiting the Bookstore at www.isri.org.)
   Though Mattia acknowledges the importance of guards, he believes that processors should take the protection a step further by engineering their guillotine shears for safety. “It doesn’t take that much more horizontal area to move sorters out of the direct firing line of the shear throat,” he says. “A straight line from the shear means a direct line for shrapnel.”
   One manufacturer says the best step is to create a “danger zone” in front of the shear and turn the conveyor 90 degrees so sorters are off to the side and, thus, not in a direct line from the shear throat. Another manufacturer suggests building a cage of 1/2-inch steel plate around the front of the shear, with a hinged plate where the scrap is discharged to the conveyor.
   Mattia also recommends taking safety up a notch—literally: “An elevated shear sorting station set above and/or at an angle to the shear’s mouth can significantly decrease the chance for shrapnel injuries,” he asserts. As he explains, shrapnel is most powerful when it stays in a horizontal path, but “the chance of it ricocheting upwards is remote.”
One processor raised his sorting station 8 feet above the ground and uses two conveyors to elevate the sheared scrap to the station. Also, rubber belting is hung in strategic areas to thwart potential lines of flying shrapnel, and no one is allowed on the ground in the area when the shear is operating. If someone wants to enter the shearing area, he or she must contact the foreman, who then instructs the shear operator to shut down the machine. 
   Processors and manufacturers agree that elevating the sorting station not only helps prevent shrapnel accidents, it also makes it easier for workers to handle the sheared material. Rather than lifting the heavy scrap, for instance, workers can simply push the metal from the table into a chute. The metal then slides into a bin or container, which can be hauled away by truck.

Maintenance: Locking Out, Staying Sharp, Crossing Off 
Lockout/tagout is the universal requirement for virtually all shear maintenance. Before an employee works on any part of a guillotine shear, all movable parts should be fully retracted. Then, deenergize the electricity and depressurize the hydraulics, shutting off the main power supply and releasing the hydraulic pressure retained in the shear.
   One operations manager says his maintenance employees are also required to wear a full-body harness when working on the shear, with the harnesses attached to hookups on the machine. As the manager explains, “There’s a possibility of falling off a shear during routine maintenance, and we don’t want that to happen to our people.” 
   He also emphasizes the importance of not rushing employees during maintenance work. “We allow eight hours to change a set of blades, and there are 40 entries on our checklist for changing blades,” the manager notes. “The procedure must be followed. There are no gray areas here.”
   There’s also universal agreement that shear knives need to be kept sharp and properly aligned. Misaligned blades will apply a tearing force rather than a cutting force to a piece of scrap. That force can propel shrapnel toward workers in unprotected areas.
   The guillotine shear head and the mechanism that delivers it to the attached blades present additional safety problems. In one instance, workers performing maintenance on a shear’s hydraulic system secured the shear head in the “up” position using a pin mechanism, but the pin didn’t hold. One individual was killed and another lost eight fingers. Mattia recommends that one or more safety devices be in place to keep the shear head from falling when it must be worked on in an up position.
   The compression box on a guillotine shear is another potential hazard for employees. In one incident, maintenance personnel were checking the function of refurbished pistons installed on a compression-box lid. They directed the lid to be placed in a ¾-open position. No sooner had they stepped out of the box than the heavy lid came crashing down. An investigation found that the pistons had been accidentally stripped, which explained why they couldn’t hold up the heavy lid in the ¾-open position.
   After this close call, the company implemented a new rule forbidding any worker from entering the compression box unless the lid is fully open.
   For one processor, an operator checklist is a must to ensure safe operations: At this company, the shear operator does a 27-point walk-around safety inspection of the shear every morning prior to startup. This inspection includes the discharge conveyor, shear, hydraulic/electric room, operator office, and crane and grapple. At the end of a 10-hour shift, maintenance includes lubrication and a safety inspection of the shear. There’s also a weekly inspection of the shear and conveyors. “We believe that by following maintenance procedures,” the plant manager says, “we extend the life of the shear and the life of our employees.”

Technology: Pumping, Programming, and Sizing
Technological improvements continue to play an important part in making shears safer to operate and maintain, not to mention more productive and versatile. The manufacturers interviewed for this article generally agreed that the three most dramatic changes in guillotine shears over the years have been in the areas of hydraulics, electronics, and size.
Hydraulics. There was a time when the hydraulic pressure in shear cylinders was 2,000 to 2,400 psi. Then it increased to 3,000 to 3,500 psi. Now it’s going to 5,000 psi. Will it go higher? Opinions vary, but hydraulics manufacturers will control those developments more than shear manufacturers.
   What the higher pressures have meant is more force from a smaller cylinder and faster cycle times. Among their benefits, smaller cylinders require less raw material to manufacture (lower cost), less weight (lower shipping costs), less weight during maintenance (easier handling), and less power to operate (lower electrical costs). 
   One manufacturer points out that the high-pressure system is a European development. As he notes, “The piston pump generally has a smaller pipe and cylinders and greater speed in moving all components of the machine, which means an increase in cutting strokes and greater productivity.” 
Electronics/Computerization. Improved electronics and computerization have made shears work smoother and made them safer to operate and maintain. Programmable logic controls (PLCs) have eliminated many manual controls and much of the human thought process. Electronic sensors monitor what the machine is doing, continuously feeding information to the PLC system. The PLC can then indicate, for instance, when the oil pressure is too high or too low and when the hydraulic filter is clogged, eliminating guesswork for the operator. 
   Modern shears can also display all of the shear functions on a “mimic” panel—a flat electronic board with lights that show all moving shear parts in sequential order. When a problem occurs, the operator sees a blinking light on the panel. If the problem is more difficult, some shears can be diagnosed by the factory via a modem.
   In today’s shearing world, radio remote-control technology is used so that the shear operator can also control the crane that feeds material into the shear. According to one manufacturer, this approach enhances production, with the compression box and shear running in complete automatic cycles while the operator focuses on feeding the machine.
   In other cases, the crane operator runs the shear. Regardless, the result is the elimination of one employee since only one person is required to run the crane and the shear simultaneously.
Radio remote-control technology can also be helpful during maintenance work. One manufacturer, for instance, offers a hand-held, battery-operated unit that can control every function of the shear, which means that “the maintenance man can be where he needs to be and see what he needs to see.”
Size. According to one manufacturer, improved materials have resulted in smaller and lighter shears that are portable. “These mobile shears usually incorporate all of the hydraulic and electrical advances of the big shears and are very efficient,” he says. “They are, however, limited in capacity when compared to the big shears, relatively speaking.”
   Another shear maker claims that more of the smaller, portable shears are being sold these days and estimates that port-able shears can handle 80 percent of the material being processed by big shears.
   Big or small, stationary or portable, there appears to be a guillotine shear to meet every need in today’s market. All that’s needed to make it “shear magic” is a commitment from processors to operate the equipment safely. •

Jim Fowler is retired publisher and editorial director of Scrap.