The good old days? Not for machine operators.

History of U.S. Machine Safeguarding

When manufacturing moved from small shops to factories during the Industrial Revolution, inexperienced, often very young workers were confronted with a confusing jumble of moving belts, pulleys and gears. While pre-industrial craftsmen faced risks from kilns and hand tools, industrialization introduced massive steam engines and fast-moving machines. Adults and children, some as young as four years old, operated unprotected machinery 12-16 hours a day under conditions unheard of today, with many losing their lives.

Safeguarding History

In America the use of labor saving machines was driven by a regulatory climate that discouraged employer’s interest in safety. As a result, manufacturers at the time developed machinery that was both highly productive and very dangerous. Overworked American factory workers in the 1900s faced life with missing limbs, damaged vision and hearing, lung infections, and severe burn injuries.

Child Worker Injury

Workers who were injured might sue employers for damages, yet winning proved difficult. If employers could show that the worker had assumed the risk, acted carelessly or had been injured by the actions of a fellow employee, courts would usually deny liability. Only about half of all workers fatally injured recovered anything and their average compensation amounted to only half a year’s pay. Because employee accidents were so cheap, industrial machinery was developed with little reference to safeguarding.

Not unexpectedly, reports from state labor bureaus were full of tragedies that struck the unlucky. These reports spurred the budding labor movement to call for factory safety. In 1877, Massachusetts passed the Nation’s first factory inspection law. It required guarding of belts, shafts and gears, protection on elevators, and adequate fire exits. Its passage prompted a flurry of state factory acts. By 1890, nine states provided for factory inspectors, 13 required machine safeguarding, and 21 made limited provision for health hazards.

Safeguarding HistoryOn the national level, Congress passed a federal employers’ liability law in 1908 that made it more expensive for companies to have a machine accident on their books. Thanks to the new law, worker injuries that once cost companies $200 to resolve now cost almost $2,000. In 1910, the state of New York created a workmen’s compensation law that forced companies to automatically compensate for workplace injuries, eliminating the need for families to take corporations to court. By 1921, 43 more states had followed New York’s lead and established their own compensation laws. Compensation laws and other liability costs suddenly made workplace injuries an expensive proposition for many employers.

What followed was a slow but steady increase in machine safeguarding. Manufacturing companies began to work to create safer production equipment, and managers began getting tasked with identifying machine dangers.

In 1913, the U.S. Bureau of Labor Statistics documented approximately 23,000 industrial deaths among a workforce of 38 million — a rate of about 61 deaths per 100,000 workers. Although the reporting system has changed over the years, the figure dropped to 37 deaths per 100,000 workers by 1933 and 3.5 per 100,000 full-time-equivalent workers in 2010. A major contributor to the trend in fewer deaths was machine safeguarding.

Safeguarding HistoryAfter WWII accidents declined as powerful labor unions played an increasingly important role in worker safety. Personnel Protective Equipment (PPE) became a requirement with gloves, masks and aprons given to workers. Posters were hung throughout the plant floor reminding workers of their responsibility to think and act in a safe manner. Basic guards and safety mats became common features around industrial machinery. Also, the American Standards Association published its “Safety Code for Mechanical Power Transmission Apparatus” in the 1940s. Very similar to OSHA 1910.218 it was written to serve as a guide for machine manufacturers in guarding systems. The National Safety Council found that the injury frequency rate dropped from 15 injuries per 100 full-time workers in 1941 to 9 in 1950. By 1956, it reached a decade low of 6 per 100 workers. As impressive as those numbers were, the on-the-job death toll in the 1950s remained a stubborn 13,000-16,000 workers annually.

Nixon Signs OSH ACTIn the 1960s economic expansion again led to rising injury rates with 14,000 workers dying each year. An additional 2.2 million workers were injured on the job. Resulting political pressures led Congress to establish the Occupational Safety and Health Administration (OSHA) in 1970. On December 29, 1970, President Richard Nixon signed into law the Williams-Steiger Occupational Safety and Health Act (OSH Act), which gave the Federal Government the authority to set and enforce safety and health standards for most of the country’s workers. This act was the result of a hard fought legislative battle that began in 1968 when President Lyndon Johnson unsuccessfully sought a similar measure.

In the House, Representative William A. Steiger worked for passage of his bill by saying: “In the last 25 years, more than 400,000 Americans were killed by work-related accidents and disease, and close to 50 million more suffered disabling injuries on the job. Not only has this resulted in incalculable pain and suffering for workers and their families, but such injuries have cost billions of dollars in lost wages and production.”

Machine Safeguarding AssessmentsWhen the agency opened for business in April 1971, OSHA covered 56 million workers at 3.5 million workplaces. Today, 105 million private-sector workers and employers at 6.9 million sites look to OSHA for guidance on workplace safety and health issues.

Safeguarding technology and requirements have come a long way since the industrial revolution. Advanced light curtains, interlocked guards, laser-guided systems and presence sensors are now commonplace. Despite this progress, the lack of machine guarding has been named to OSHA’S Top 10 Most Cited Violations List virtually every year since the list began. In 2018 OSHA handed out nearly 2,000 violations to companies for failing to have machines and equipment adequately guarded, underscoring how much work there is left to do.

In many respects, we take today’s focus on machine safety for granted. However, by reviewing history we can see how it has benefited society by radically reducing accidents and deaths.

Safeguarding History

Minimize Conveyor Injury Risks with Safeguarding

While conveyor belts are integral facets of the distribution process and most warehouses could not function without them, they also pose the potential to cause serious injuries and sometimes even fatalities. In fact, the U.S. Department of Labor, Bureau of Labor Statistics has reported that over 40 workplace fatalities a year are the result of conveyor accidents, along with 9,000 injuries.

While in motion, conveyor systems have inherent and obvious dangers. Belts continuously move at speeds up to 600 feet per minute or 10 feet per second. There are many pinch-points within their machinery, any of which could cause an injury to a worker. Common employee injuries incurred working with conveyors include arm and hand amputations, finger lacerations, burns, scrapes and broken bones. Even when employees are being careful, accidents can happen. It’s easy for loose clothing, jewelry or hair to get trapped in conveyor belts. If workers aren’t paying attention, they could get caught in the machine.

Every conveyor belt injury in a warehouse is costly, affecting worker morale, availability of trained labor, lost production, and increased overhead due to insurance premiums, along with mountains of paperwork, lawsuits and possible fines from government regulatory agencies. Conveyor belt injuries account for nearly 25% of all workers’ compensation claims. Safeguarding conveyors protects employees from injuries, and companies from potential financial ruin.

Safeguarding Conveyors
Safety considerations for conveyor design are detailed in ASME B20.1-2018: Safety Standard For Conveyors And Related Equipment.

ASME B20.1-2018 applies to the design, construction, installation, maintenance, inspection, and operation of conveyors and conveying systems in relation to hazards. The conveyors covered can be bulk material, package, or unit-handling types installed for permanent, temporary, or portable operation. OSHA has also issued its own standard 1926.555(s)(1), General Conveyor Safety Requirements. In many cases, local municipalities and equipment manufacturers will require standards above and beyond ASME and OSHA be met.

Because conveyor designs vary, each conveyor should be evaluated to determine what primary safeguarding methods and energy control practices are required. For instance, a chain conveyor introduces the hazards of nip points when a chain contacts a sprocket. As a result, the primary safeguarding method would be enclosing the moving chains. If this isn’t possible, barrier guards can be installed around moving points so that nip and shear points can be eliminated by a guard. Secondary guarding options would include safeguarding by distance or the use of awareness devices.

Rather than concentrate on specific details of unique conveyor designs, for the purpose of this article, we are going to look only at three basic requirements of conveyor safeguarding: emergency stops, guards and motor starters.

Emergency Stops: The only conveyors that don’t require emergency stops or “e-stops” are ones mounted more than eight feet above the working surface, since those are guarded by their elevation, a situation called “guarded by location.” Conveyors that are accessible to operators must be equipped with e-stops.

conveyor belt safeguarding
 
According to both ASME B20.1-2018, remotely and automatically controlled conveyors where operator stations are not manned or beyond contact shall be furnished with emergency stop buttons, pull cords, safety-rated limit switches or similar emergency stop devices. As a general rule of thumb an operator should be able to stop any conveyor within his or her line of sight by activating the nearest emergency stop. ASME also requires that all emergency stop circuits should fail in the event of a power loss to the emergency stop circuit. Employees must be familiar with the location and function of e-stops to allow them to make fast decisions on using them. E-stop training should be provided to all employees regarding where they are located, when to use them, and how to access them.

As for restart, OSHA requires that “emergency stop switches shall be arranged so that the conveyor cannot be started again until the actuating stop switch has been reset to running or ‘on’ position.” ASME goes further, requiring that the starting device be locked out or tagged before any attempt is made to remove the cause of the stoppage. Besides having the activated emergency stop switch or pull cord reset, an audible warning signal must be sounded immediately before starting up the conveyor.

Depending upon the size of the conveyor, multiple start buttons may need to be activated. Modern conveyors may feature a Human Machine Interface (HMI) that allows operators to remotely identify the location of the tripped emergency stop on a display. Once the local emergency stop has been reset, the system can be remotely restarted via the HMI.

Finally, e-stops should never be modified for any reason by unqualified personnel. Monitor e-stops to ensure employees have not misused, modified, or disconnected them.

Guards: ASME B20.1-2018 requires conveyor with accessible nip points on spools and pulleys be guarded to prevent contact by a worker, and that a conveyor have guards or sideboards to prevent material from falling from the conveyor into areas occupied by workers if the falling material presents a hazard of impact injury or burn. Barriers, enclosures, grating, fences, or other obstructions that prevent physical contact with conveyor components are considered to be guards. When the guard is used as the primary safeguarding method, a guard opening scale can be used to ensure no employee cannot reach under, over, around, or through the guard. Any openings created by the guards must be checked for compliance with ANSI/CSA safety standards. Hand railing is not acceptable to limit access to a pinch point as it can be breached easily.

Most serious accidents and fatalities involving conveyors result from inadequate guarding. Guards are sometimes removed by plant employees for maintenance purposes, or because they obstruct an employee’s access doing work, exposing sharp machinery, gears, chains, and moving parts that are extremely dangerous. To help ensure worker safety, lock out conveyors when in service, and operate equipment only when all approved covers and guards have been reinstalled.

Lockout/Tagout: Conveyors are widely thought to not require a lockout/tagout procedure, which is incorrect. According to the OSHA 29 CFR 1910.147, OSHA expects that all equipment with more than one energy source, including energy that can be locked and energy that must be dissipated manually, must require a machine-specific procedure. Conveyors have both electrical energy and kinetic energy. Additionally, adjacent equipment feeding the conveyor can cause a hazard if still running during conveyor service. According to OSHA data, workers who operate conveyors, packaging equipment and printing presses experience the highest number of accidents associated with lockout/tagout failures.

Lockout / tagout
 
Whenever a conveyor is under repair or maintenance, it must be stopped with power sources locked out and tagged out. Exceptions may be given to conveyors that need power for testing or making minor adjustments. For more about “alternative LOTO measures” consult ANSI/ASSE Z244.1 for expanded guidance beyond OSHA’s regulatory limitation to tasks that are “routine, repetitive and integral to production operations”. Following the Hierarchy of Control model, ANSI/ASSE Z244.1 provides detailed guidance on if, when, and how a range of alternative control methods can be applied to result in equal or improved protection for people performing specific tasks.

When it comes to conveyor service, maintenance work should only be carried out by fully trained, highly qualified professionals. These professionals will ensure proper lockout/tagout procedures are followed, and to block or disengage all power sources to the conveyor — electrical, hydraulic, air and gravity. Keep in mind that even the best trained technicians are occasionally injured by a conveyor. Untrained staff should never attempt a conveyor system repair.

As with any industrial equipment, conveyors are capable of causing grave injuries if not safeguarded according to established standards. However, it is equally important that employees working around conveyor systems are trained regarding potential hazards. Constant vigilance and a safeguarded conveyor are vital to keeping your warehouse and facility safe.

Valve Safety Trains Require Regular Inspections, Maintenance and Training

Thermal processes are used to alter the physical, and sometimes chemical, properties of a material or coating. Two common examples of thermal processing would be high-temperature operations such as heat treating, and low-temperature operations, for instance drying or baking. Heat treating involves the use of heating or chilling, normally to extreme temperatures, to modify a material’s physical properties — making it harder or softer, for example. Many industries use baking, drying or other lower temperature heating processes to modify aspects of a material or coating. Additionally, facilities may have incinerators for oxidizing pollutants, or air heaters for tempering climate air. Applications for thermal processing are virtually endless.

At the heart of all thermal processes is a valve safety train. These fuel-delivery devices maintain consistent conditions of gasses into furnaces, ovens, dryers and boilers, among others, making them crucial in assuring safe ignition, operation and shutdown. Equally important, they keep gas out of the system whenever equipment is cycled or shut off.

Valve safety trains are critical to the operation of combustion systems. Despite being used daily in thousands of industrial facilities, awareness on their purpose and function may be dangerously absent because on-site training is minimal or informal. To many employees on the plant floor this series of valves, piping, wires and switches is simply too complex to take the time to understand. What is known can be dangerously misunderstood.

A valve safety train isn’t a single piece of equipment. Instead, it has many components including regulators, in-line strainers (“sediment traps”), safety shut-off valves (SSOV), manual valves (MV), pressure switches, and test fittings logically linked to a burner management system. Flame-sensing components make sure that flames are present when they are supposed to be, and not at a wrong time. Other components may consist of leak-test systems, gauges and pilot gas controls. At a minimum there are two crucial gas pressure switches in a valve safety train, one for low pressure and one for high pressure. The low gas pressure switch ensures the minimum gas pressure necessary to operate is present. As you would assume, it will shut off fuel to the burner if the gas pressure is below the setpoint. The high gas pressure switch ensures an excessive pressure is not present. It too will shut off fuel if the gas pressure is too high. Both switches must be proven safe to permit operation. Additionally, there will be an air pressure switch to ensure sufficient airflow is present to support burner operation. Some systems have supplementary pressure switches, such as a valve-proving pressure switch. Switches such as these are typically used to enhance safety or provide other safety aspects specific to that application’s needs. A multitude of sensors within the valve safety train — pressure switches, flame detectors, position indicators — and isolation and relief valves work together in concert to prevent accidents.

Valve safety trains must be compliant with all applicable local and national codes, standards, and insurance requirements. The most common of these for North America are NFPA, NEMA, CSA, UL, FM. Annual testing and preventive maintenance are not only an NPFA requirement, but also oftentimes required by insurance agencies, equipment manufacturers, and national standards, including ANSI, ASME, and NEC.

Understanding of fuel-fired equipment, especially the valve safety train, is necessary to prevent explosions, injuries and property damage. The truth is, although valve safety trains are required to be check regularly, they are rarely inspected, especially when maintenance budgets are cut. And while codes require training, they offer very little in terms of specific directions.

Don’t wait for a near-miss or accident to inspect and/or upgrade your valve safety train. For more information on Rockford Systems Combustion Safety Solutions, please visit or call 1-800-922-7533.

Please read our extensive set of Combustion Safety Questions & Answers HERE.

Please read our Combustion Safety press release HERE.

Evaluating the Machine Guarding ROI

Insurance studies indicate machine safeguarding provides an excellent opportunity for businesses to reduce bottom-line operating costs by eliminating both the direct and indirect costs of accidents.

Consider this:According to the 2018 Liberty Mutual Workplace Safety Index, serious, non-fatal workplace injuries amounted to nearly $60 billion in direct U.S. worker compensation costs. This translates into more than one billion dollars a week spent by businesses on injuries. Another study, this one conducted by Colorado State University, set the total direct and indirect cost of workplace injuries at $128 billion. For its part, the National Safety Council (NSC) set the total cost to society of occupational injuries and deaths at $151.1 billion.

So how does an organization evaluate the machine guarding return on investment (ROI)?

DIRECT COSTS

First off, what are the direct costs of an accident? These refer to out-of-pocket expenses like hospital and medical bills, but may also include the loss of a worker’s time because of the accident, the lost productivity by the machine involved in the accident being idled or requiring repairs, as well as the other machines further down the production line being shut down. Direct costs continue to cascade throughout the company with overtime required to make up the lost productivity or new workers who need to be hired and trained.

The NSC estimates that cost per medically consulted injury, counting wage losses, medical expenses, administrative expenses and other direct employer costs, to be $32,000. This varies greatly by cause and nature of the injury, and which part of the body is impacted. For example, the average cost per worker compensation claims involving an amputation runs $95,204, while a crushing accident is $57,519. These two sorts of injuries are mentioned here because they are both very common in machinery-related accidents. The NSC also reports that an employee death resulting from an accident costs the company on average $1.2 million. Total medical cost to society annually from occupational injuries and deaths is $33.8 billion.

INDIRECT COSTS
Analysis reveals that the actual total cost of an accident ranges from four to ten times the direct cost stated by an insurance company once indirect costs are factored in. Indirect costs can include such things as workplace disruptions, loss of productivity, and increased insurance premiums. And of course, there are litigation and lawyer fees. Here, the sky is the limit. Lawsuits resulting from employee injuries or death, especially those involving a lack of machine safeguarding, often result in multi-million dollar settlements or verdicts. Investments targeted for company growth may need to be diverted to cover the costs of these settlements, putting the future of the company in jeopardy.

While it is not calculated as an indirect cost, a poor safety record can make the difference between a company winning or losing bids, especially with government contracts. A plant with a singularly bad reputation for safety may also find itself unable to attract qualified workers or may have to pay wages well above market value to do so. Also, if the machine is locked out for investigation or until the safeguarding deficiency is abated, the company may need to outsource the work at a much higher cost. It’s also possible that the work is so specialized that it’s impossible to outsource and therefore the company loses the business.

MANAGEMENT OPINIONS ON SAFETY
A poll by Liberty Mutual Group insurance showed that the majority of executives surveyed (61%) reported that for every one dollar spent on safety, three dollars is saved. Nearly all (95%) said workplace safety had a positive effect on financial performance. OSHA estimates a 6:1 ratio for saved dollars for every one dollar invested in safety, twice Liberty Mutual’s 3:1 ratio.

Of course, if a company could be guaranteed a huge return on their safety investment, more than half the machines in the U.S. today would not be operating unprotected. Convincing upper management to commit tens of thousands of dollars on machine safeguarding when a return may not be seen for years can be a hard sell. In this situation, safety professionals can stress that although cost savings are a motivator, safety’s biggest ROI comes in the form of human capital. Money savings from fewer injuries, increased productivity, and higher morale are all additional benefits.

Safeguarding press brakes without sacrificing productivity

Technology advances can keep the operator safe and the press brake running

Even though the U.S. has some very strict machine guarding regulations, the U.S. Department of Labor reports that press brake operators in this country suffer more than 350 amputations per year—and these are only the reported injuries. The question is why?

For one, by their design, press brakes are very dangerous machines, much more so without proper safeguarding equipment. Injuries result because of unguarded access to the point of operation at the front of the machine and the operator’s ability to reach around the safety device to get to the point of operation at the side or back of the machine. Also, the back-gauge system creates pinch points and poses a risk to the operator with its hazardous motion. Although rare, operators also can experience blunt force trauma after being struck by ejected materials.

But perhaps the greatest threat linked to running press brakes is having the operator’s hand trapped between the part being bent and the frame of the machine (see Figure 1). If the force is great enough or the part is sharp enough, impalement or an amputation can occur.

Another factor contributing to the dangers of press brakes is the metal fabricator’s failure to perform an upfront risk assessment. This type of assessment is the critical first step in any safeguarding project and, unfortunately, seldom completed. An overall risk assessment considers hazard severity, frequency of exposure, and probability of injury, as suggested by ANSI B11.0-2015. Risk or machine safeguarding assessments should be done before commissioning any new machinery, after upgrading existing machinery, after changing the work area, and after any accident or serious incident.

Yet another dynamic contributing to press brake injuries is lack of press brake maintenance, in particular testing safety devices to ensure they are working properly and in the correct position. An unmaintained press brake, especially one with damaged tooling, can put both the machine and operator at risk for serious injury.

All of these issues can be addressed in a few moments. It is time well spent to ensure that the machine is safe to operate. Having said that, not all shops will commit to that type of preparedness and maintenance. So it’s not a question of if an operator will get hurt by a press brake; it’s a question of when.

What Are the Safety Standards?
The Occupational Safety and Health Administration (OSHA) does not specifically address mechanical or hydraulic press brakes, but the machines are commonly cited under the general duty clause 1910.212, which covers failure to provide adequate protection for plant employees from known machine hazards. Most commonly, the industry follows the ANSI standard for press brakes, ANSI B11.3, for safeguarding method guidance and then ANSI B11.19 for design criteria.

The original B11.3 standard was approved in 1973 and revised in 1982 and again in 2002. The current 2012 standard, ANSI B11.2-2012, includes the new topics of close proximity point of operation, active opto-electronic protective devices (AOPD), and a safeguarding means called safe speed.

Safe speed is protection for the operator when safeguarding is not provided by a light curtain, such as after the optical system is muted for the bending operation to occur. Safe speed must be monitored automatically, so the press brake ram does not exceed 10 mm/s and for the machine closing movement to be stopped if this limit is exceeded. To insert these new safe speed requirements into B11.3, the committee drew on experience with this requirement in Europe and its corresponding EN 12622 standard.

Does Safeguarding Hinder Productivity?
A widespread misconception in the industry is that safeguarding a press brake prevents or hinders employees from making production quotas. However, an Aberdeen Group research study (“Integrated Safety Systems: Ensuring Safety and Operational Productivity”) concluded that companies that have taken steps to invest in safeguarding not only improve plant safety, but realize superior operational performance and overall equipment effectiveness (OEE). The 20 percent of best-in-class companies that had the highest OEE also had the lowest safety incident rate. The top companies typically had an OEE on average of 90 percent and an injury incident rate of 0.05 percent, while the bottom 20 percent of companies had an OEE of 76 percent and an injury frequency rate of 3 percent, which is 60 times higher. Top manufacturers were also able to achieve a 2 percent unscheduled asset downtime rate, versus a 14 percent rate for the laggard group in the study.

Figure 1
When it comes to older bending machinery, nothing really acts as a barrier between the press brake and the machine’s operator.

What makes these statistics possible is modern safeguarding tools. Some of these options are awareness and barrier guards, light curtains, two-hand controls, and laser AOPD.

First, however, a word or two about retrofitting. When retrofitting older machines, installers must take great caution to ensure that the new technology does not decrease the safety of the machine or add new hazards. Sometimes an older machine simply cannot be brought up to today’s standards. At that point the installer must evaluate the situation and ensure the full machine installation becomes safer overall than its original state with the new safeguarding. If not, he needs to step back and consider the options. ANSI B11.3-2012 gives direction on this topic.

Awareness Barrier. The backs of press brakes cannot be left wide open. Two hazards often lurk here: reaching the dies from the back and the possibility of a multi-axis back gauge moving and creating pinch points. As to exactly what is required on the back of equipment often depends on local OSHA interpretation. At the very least, an awareness barrier, like a railing, chain, or cable with a “danger” or “warning” sign complete with pictographs, not just verbiage, should be installed. Awareness barriers are bare-minimum methods in reducing risk.

Barrier Guards. Although not versatile, barrier guards on the ends of most press brakes are effective when used in conjunction with other safeguarding devices (see Figure 2). They also can be used to mount/support light curtains, adding to their value. Barriers can have openings for material to be fed into the die area, but do not allow for hands into that area.

Barrier guards reduce the risk of the operator getting his hands pinched when he reaches between the punch and die from either side of the press brake or reaches between the back-gauge system and tool. By OSHA’s definition, a guard must prevent people from reaching over, under, through, or around it. Guards must meet one of two measurement scales—the OSHA guard opening scale or the ANSI/CSA guard opening scale—to ensure that a small hand can’t reach far enough through any opening to get hurt.

Barrier guards can be fixed or interlocked. The interlocked design prevents misuse and is required to be either electrically interlocked or fixed in place using a fastener that requires a tool for removal. They’re often hinged or sliding to allow easy access to the point of operation for machine setup (access to limit switches or other levers and dials), tool change, or maintenance tasks.

Light Curtains. These safeguarding tools have been around since the mid-1950s. They consist of a vertically mounted transmitter and receiver with closely spaced beams of laser creating a flat sensing field. When fingers, hands, or arms reach through that sensing field, the press cycle is prevented or stopped to avoid operator injury.

One of the reasons that press brakes make a good application for light curtains is that they can be stopped midcycle very quickly. Hydraulic press brakes stop quickly if maintained properly. Mechanical press brakes may not. Air clutch machines have reasonable stop times, but mechanical friction clutch (MFC) machines are known for stopping very slowly. Quite often light curtains can’t be used on MFC press brakes because the safety distance can end up being 2 to 3 feet.

Like any safeguarding device, light curtains should be “function-tested” before every operating shift to ensure that they are continuing to provide protection. Make/model-specific function-test procedures are usually available on each light curtain manufacturer’s website.

Two-Hand Controls. These controls are considered a safer means of cycling a press than a footswitch because both hands must be in a safe position to use them. When a press is cycled with a footswitch, hands can be anywhere. It’s possible to use a two-hand control as a safeguarding device as well during press brake operation.

Figure 2
The barriers on the side of this press brake have light curtains attached to them, providing the press brake operator with two layers of protection.

Most operations require that the part be held when bending, so two-hand control is rarely used to cycle a press brake or used as the point-of-operation safeguard. The part would have to be fixtured and supported by a backgauge to use a two-hand control.

Laser AOPD. The newest entry into the press brake safety category is the laser AOPD (see Figure 3). Inclusion of laser AOPD technology in the B11.3-2012 is a welcome addition to the standard that now gives press brake manufacturers, dealers, and users a clear guideline to implementing this technology safely for retrofit applications (B11.3 subclause 8.8.7 —Close Proximity Point of Operation AOPD Safeguarding Device).

It is important to note here that AOPDs are an acceptable method of safeguarding hydraulic press brakes only per ANSI B11.3 and also following most manufacturers’ specifications.

A unique feature of AOPDs is that they are designed to be mounted with zero safety distance, unlike light curtains that must be mounted at a calculated safety distance (see Figure 4), as outlined in ANSI B11.3. Safe speed safeguarding is based on a ram speed of 10 mm/s or less, providing that speed is carefully monitored. Again, this new method of protection can be applied only to hydraulic press brakes (and potentially servo-drive press brakes). Because of their close proximity point of operation, AOPD systems are best-suited for applications such as box bending, bending with flanges, or where light curtain effectiveness is diminished due to excessive blanking or muting.

Press brakes are very dangerous machines, much more so without proper safeguarding equipment. When safeguarding equipment is engineered, installed, and operated correctly, it provides positive, business-enhancing benefits while mitigating risks and reducing insurance and energy costs. Metal fabricators also should recognize the payback of reducing costs associated with accidents, medical expenses, and regulatory noncompliance.

For more information about safeguarding press brakes, please contact us at 1-800-922-7533.