SAFETY IN NUMBERS: Stop Time Measurements

Stop-Time Measurements Keep Safeguarding Equipment in Peak Performance

We’ve all heard the phrase “what a difference a day makes,” yet when it comes to industrial safeguarding, the concern isn’t days, hours or even minutes. It is the milliseconds it takes for a machine operation to stop. That fraction of a second can make the difference between a life-changing injury or a safe machine cycle, the difference between a valued employee going home or being taken to the emergency room.

How can we assure the right outcome? How do we determine if a machine will stop in time?

The answer is specialized equipment called “Stop-Time Measurement” devices (STM). An STM is used to determine the total response time from the triggering of a machine’s operating control or a safeguarding device… to the exact moment when a dangerous movement comes to a halt. Take, for example, the time it takes for a press brake cycle to stop when a finger or hand enters the point-of-operation zone, or the time between when a light curtain is activated and when the machine comes to a complete standstill.

Once the stop-time data is captured by an STM in either milliseconds or inches, it is applied to an established formula to calculate the minimum safety distance required to install safety devices. A record of the measurement can be printed out, or alternatively, the device can be plugged into a PC where the measurements can be recorded and documented.

Doing the Math
According to OSHA, the majority of machine-related accidents happen as a result of a reflex action or when the operator is not paying attention. For example, a machine operator may instinctively reach into the machine when there is an issue. Or they will be so focused on a task that they’ll cross the threshold into a hazardous area without being aware of it. In these events, it is critical that a machine’s safety devices stop operations before the hazard is reached. In addition, accidents may not be the fault of the operator at all. There are instances where integrators do not program the field of coverage — the area being monitored by the light curtain, for instance — at the proper safety distance and puts the operator unknowingly at danger.

So what is the correct distance? The basic calculation for ‘safety distance’ comprises approach speed, overall stop time and penetration depth factor.

The standard formula is below:
DS = K (T) + DPF
where:
DS = the safety distance
K = the maximum speed that an individual can approach the hazard
T = the total time to stop the hazardous motion
DPF = the depth penetration factor of the safeguarding device

There are other variations on this calculation; for example, where a light curtain is in operation, the calculation requires both the resolution and the response time of the light curtain to be factored. Most STM devices perform calculations internally so the operator doesn’t need to concern themselves with all the details of the math, only the results to act upon.

In the United States there are two formulas that are used to properly calculate the safety distance. The first, the OSHA formula, is the minimum requirement for the calculation of the safety distance. The second is the ANSI formula, which incorporates additional factors to be considered when calculating the safety distance. Rockford Systems recommends the use of the ANSI system since it is the more comprehensive of the two. The formula is included in ANSI standards B11.19-2010 and Robotic Industries Association (RIA) R15.06-1999 (R2009), as well as CSA Z142-10, Z432-04 and Z434-03.

Stop-Time Measurement Service
For all linear and rotating motion equipment, Rockford Systems offers STM service for newly installed safety devices as well as for the periodic validation of existing safety devices. Periodic safety distance validation with an STM is required for AOPD systems, light curtains, 2-hand control systems, emergency stop devices, pressure-sensitive protective strips or mats, interlocking guards, doors and gates, as well as other safety devices and controls equipment used during production. This is necessary since factors like maintenance, brake wear, and alterations can increase the machine’s stopping time. If a machine stops slower than it did when it was originally commissioned then components will need to be adjusted to continue providing the correct level of safety. Stop time measurement is able to detect changes at an early stage, so that appropriate action can then be taken. For these and other reasons it is important to perform at least an annual stop time analysis. Rockford Systems STM services are mainly employed on reciprocating (stroking or cycling) machines, such as mechanical or hydraulic presses and press brakes, but can also be used on machines that rotate, such as lathes, mills, and drills.

Location of a safety component, whether hard guarding or electronic, is based upon the machine’s stopping time. Simply stated, a safety component should be placed far enough away from the risk area that it is not possible to reach the hazard before the machine has stopped. Safety devices are then installed using the minimum safe distance. Reference our OSHA Safety Distance Guide Slide Chart.

Regularly checking shop machinery with Stop-Time Measurements and maintaining a log of the results empowers a company to be proactive in establishing a safety maintenance program. It ensures that safeguarding equipment on machinery works as designed to achieve greater worker safety, productivity and profits.

Lack of Machine Guarding Again Named to OSHA’S Top 10 Most Cited Violations List

Every year around this time, the awards season kicks off with the Emmys, Golden Globes and the grand daddy of them all, the Oscars, eagerly announcing their lists of nominations. At the same time — and on a far more somber note — another roll call is issued, this one from the Occupational Safety & Health Administration (OSHA). Unlike Hollywood’s awards celebrations, however, no one wants to be nominated for OSHA’s Top Ten Most Cited Violations list, let alone take home the top prize.

OSHA revealed its 2017 Top 10 list at the National Safety Congress & Expo in the Indiana Convention Center. The top ten are:

1. Fall Protection – (1926.501): 6,072 violations
2. Hazard Communication (1910.1200): 4,176 violations
3. Scaffolding (1926.451): 3,288 violations
4. Respiratory Protection (1910.134): 3,097 violations
5. Lockout/Tagout (1910.147): 2,877 violations
6. Ladders (1926.1053): 2,241 violations
7. Powered Industrial Trucks (1910.178): 2,162 violations
8. Machine Guarding (1910.212): 1,933 violations
9. Fall Protection – Training Requirements: 1,523 violations
10. Electrical – Wiring Methods (1910.305): 1,405 violations

While reviewing the list, it is important to remain aware that the Federal Occupational Safety & Health Administration (OSHA) is a small agency. When tallied up to include its state partners, OSHA only has 2,100 inspectors who responsible for the health and safety of 130 million American workers, employed at more than 8 million work sites. This translates to about one compliance officer for every 59,000 workers. As a result, some serious injuries are not reported and thousands of potential violations go without citation or fines. In fact, numerous studies have shown that government counts of occupational injury are underestimated by as much as 50 percent. Employers are required to record all injuries meeting the OSHA’s ‘recordable injury’ criteria (except minor first-aid cases) on the OSHA 300 Log, and those meeting the ‘reportable’ criteria (e.g., hospitalizations or deaths), are to be reported to OSHA immediately, or within 24 hours of occurrence, as per the criteria defined in 29 CFR 1904. But it doesn’t mean all of them do.

MACHINE (UN)SAFEGUARDING IN TOP 10 MOST CITED VIOLATIONS
The absence of required machine safeguarding remains a perennial member of OSHA’s Top 10 Most Cited Violations, and 2017 was no exception. It was named number eight on the list with a total of 1,933 violations. These violations refer to OSHA 1910.212 for failing to have machines and equipment adequately guarded. Any machine part, function, or process that might cause injury should be safeguarded. When the operation of a machine may result in a contact injury to the operator or others in the area, the hazard should be removed or controlled.

A lack of machine safeguarding also held the dubious distinction of making the list of OSHA’s ten largest monetary penalties for the year — not once but four times. In fact, the largest proposed monetary penalty, a staggering $2.6 million (USD), arose from an incident where a worker was crushed to death while clearing a sensor fault in a robotic conveyor belt. OSHA alleges that the company failed to use energy control procedures to prevent robotic machinery from starting during maintenance. The manufacturer also was cited for exposing employees to crushing and amputation hazards as a result of improper machine guarding, plus failing to provide safety locks to isolate hazardous energy.

Despite these headline fines, the repercussions for employers putting workers in harm’s way remain small under the 1970 Occupational Safety and Health Act. The average federal fine for a serious workplace safety violation was $2,402 in fiscal year 2016, according to the most recent report by the AFL-CIO. And the median penalty for killing a worker was $6,500.

According to the most recent Bureau of Labor Statistics data, manufacturing plants reported approximately 2,000 accidents that led to workers suffering crushed fingers or hands, or had a limb amputated in machine-related accidents. The rate of amputations in manufacturing was more than twice as much (1.7 per 10,000 full-time employees) as that of all private industry (0.7). The bulk of these accidents occurred while removing jammed objects from a machine, cleaning or repairing the machine, or performing basic maintenance. These injuries were all largely preventable by following basic machine safeguarding precautions. Rockford Systems is committed to helping organizations reduce injuries and fatalities due to a lack of or non-compliant machine safeguarding. By creating a culture of safety in the workplace, Rockford Systems can help plant managers significantly reduce the number of on-the-job injuries and fatalities that occur annually, plus guard against hefty fines, lost production and increased insurance premiums.

Which leads to the question… “Where do we begin?”

TRAINING AND EDUCATION

Ignorantia juris non excusat (“ignorance of the law excuses not”). Recognizing that education is key to safety, Rockford Systems has offered its Machine Safeguarding Seminars for more than two decades. Thousands of safety professionals have attended the seminars from industries as diverse as aerospace and metal fabrication, to government and insurance.

Held ten times a year at our Rockford, Illinois headquarters, the 2.5 day seminars address key topics in safeguarding with a focus on OSHA 29 CFR and ANSI B-11 standards as they relate to specific machine applications and production requirements. Safeguarding equipment, both old and new, is not only explained in depth in the classroom, but demonstrated under power on the shop floor. Most of these machines are equipped with more than one type of safeguarding product so that attendees can see how different guards and devices can be applied.

Roger Harrison, Director of Training for Rockford Systems and an industrial safeguarding expert with over 25,000 hours of training experience, conducts the Machine Safeguarding Seminar.

>Another valuable educational resource is OSHA-10 General Industry and OSHA-30 General Industry training courses, both of which cover machine guarding. All of our training can be provided at your site, if preferred. To learn more about the Rockford Systems training curriculum, please visit https://www.rockfordsystems.com/seminars/

Rockford Systems also provides a variety of FREE machine safeguarding resources for your organization. Please visit our RESOURCES page to find videos, blogs, quick reference sheets, and more or visit our YouTube channel to download past webinar recordings.

ASSESSMENTS
If your organization is interested in safeguarding solutions, consider a Machine Risk Assessment or Machine Safeguarding Assessment as the critical first step in any machine guarding process as outlined in ANSI B11. Most assessments, but not all, follow the basic steps outlined below.

Step 1 – Provide Machine List
To get started, please provide Rockford Systems a list of all machines (manufacturer, model number, and machine description of each machine) to be assessed. This machine list is needed to determine the estimated resource requirement for the onsite audit. Upon receipt of your machine list, an Assessment Proposal will be provided, generally within 24 hours of receipt. Please email your machine list and any machine photos (optional) to sheryl.broers@rockfordsystems.com.

Step 2 – Schedule Onsite Visit
During the assessment, a machine safeguarding specialist will visit your site and conduct a complete audit of all machines identified on the list and evaluate their compliance in five guarding areas (Safeguards, Controls, Disconnects, Starters, and Covers). The assessment is based on OSHA 1910.212 General Requirements (a)(1), ANSI B11 Safety Standards for Metalworking, ANSI/RIA R15.06-2012 Safety Standards for Industrial Robots, and NFPA 79. If Rockford Systems, LLC has additional specific safeguarding requirements above and beyond OSHA 1910.212 and ANSI B11, please provide them before the site visit and we will incorporate them into the assessment.

Also, during the assessment, we may request copies of electrical, pneumatic and/or hydraulic schematics and operator manuals for specific machines. This information is needed for our Engineering Department to review the control circuit for electrical compatibility of equipment being offered, to verify control reliability of the control circuit, to determine interfacing requirements of suggested equipment. If requested, this information would be needed before advancing to Step 3 below.

Step 3 – Receive Compliance Report and Safeguarding Project Proposal
Upon completion of the assessment, a Compliance Report and Safeguarding Project Proposal will be provided to that identifies where each machine is in, or not in, compliance with the above stated regulations and standards. Where not in compliance, we will suggest guarding solutions to bring the machines into compliance, along with associated costs and timeframes.

We look forward to assisting your organization with its safeguarding needs. A team member will call you within 24 hours to further discuss your needs and applications. We are here to help businesses large and small address machine safety challenges and to remove the burden of managing the growing legal complexity of OSHA, ANSI and NFPA requirements from simple turnkey solutions to build-to-spec customized solutions.

Please contact sheryl.broers@rockfordsystems.com or call 1-815-874-3648 (direct) to get started on an assessment today.

PRODUCTS
If you are looking for Machine Safeguarding Products, please visit our PRODUCTS page that offers over 10,000 safeguarding solutions for drill presses, grinders, lathes, milling machines, press brakes, power presses, radial arm drills, riveters and welders, robots, sanders, saws and more.

RETURN ON INVESTMENT
Not sure if the investment in machine safeguarding provides a return on the investment (ROI), it absolutely does and we can help you calculate it. Please read our detailed blog post on this topic.

For more information on how avoid machine injuries and fatalities, please visit www.rockfordsystems.com.

Press Brake Safeguarding To Prevent Injuries

Including In-Depth Analysis of Light Curtains vs. Laser AOPD

Press brakes are unforgiving machines and a common source of workplace amputations of hands, fingers and arms. United States Department of Labor statistics indicate an average of 368 instances of amputations annually from press brake accidents. And these are only the reported accidents.

WHY ARE PRESS BRAKES SO DANGEROUS?
The primary reasons are access to the point of operation at the front of the machine, as well as reaching around the safety device to get to the point of operation at the ends of the machine. In addition, there are pinch points and hazardous motion created by the back-gauge system.

But the dangers don’t stop there. However well intentioned, fabricators often employ lower cost, used or refurbished press brakes where the primary controls and/or condition of the machine and safety system may be suspect. Plus, original equipment manufacturers (OEM’s) generally consider the point of operation aspect of the press brake safety system to be the end-user’s responsibility. The end-user may assure, incorrectly, that the machinery arrived into the shop ready for commissioning. Lastly, press brakes have always been operator intensive, sometimes involving multiple operators, and operator behavior is not always predictable. That is why it is good practice to make one operator the leader of the crew.

OSHA/ANSI SAFETY REGULATIONS
OSHA’s machinery and machine guarding regulations (29 CFR 1910 Subpart O) require one or more guarding methods to protect employees from exposure to hazardous machine energy during the operation of press brakes. There isn’t a great deal of detail to the OSHA regulations so fabricators in search of answers would be better served by turning to ANSI B11.3-2012 which covers safeguarding of power press brakes. The B11.3 adopted EN 12622 (European standard), giving it even more specific instructions to follow and minimizing any vague, grey areas.

ANSI B11.3 is the only safety system standard specifically applicable to power press brakes used in America, and it excludes mechanical power presses; hydraulic power presses, hand brakes; tangent benders; apron brakes; and other similar types of metal bending machines. It discusses hazards associated with the point of operation at length and identifies alternative guards and devices. For example, the ‘close proximity point of operation AOPD’ safeguarding devices, which we will discuss later in this blog, and a means of safeguarding referred to as ‘Safe Speed.’ We should note that ANSI B11.0-2015 recommends risk assessments of press brakes among other equipment, offered by Rockford Systems.

PRESS BRAKE PROTECTION OPTIONS
Today, there several ways to safeguard a press brake, some better than others. All have advantages and drawbacks.

The most basic type of safeguarding is a fixed and interlocked barrier guard coupled with two-hand controls. This is not a functional solution for fabricators as a work piece is hand held in close proximity to the point of operation during the braking process and can potentially whip up as bending is taking place.

Another approach are pull backs and restraints. Both are restrictive and have limitations and for that reason, operators dislike them. Both devices shackle the operator to a machine and restricts mobility. Yet another approach is the two-hand down/foot-through device. In some cases, this will work. However, this method raises ergonomic issues and it is very slow. Not what you want in a busy, production-driven fabrication shop.

SHEDDING LIGHT ON SAFETY
A modern light curtain is a photoelectric presence-sensing device that protects against access into hazardous points and areas of the press brake. They can range from very compact to larger, more robust and resistant models that can withstand demanding ambient conditions. We should note that a stop-time measurement (STM) device is needed to calculate the safety distance on a regular basis, just as it is needed with two-hand controls.

Safety Light Curtains safeguard personnel using an LED transmitter and receiver. Any interruption of the plane of light by an object equal to/or larger than the “minimum object sensitivity” initiates an output signal. That could be a hand or a finger or a misplaced tool that will either cause the machine to stop or prevent a cycle until the blockage is removed. The operator must be outside the protected area through the entire stroke of the press brake ram. The safety distance between the light curtain and the machine depends on the application, the type of light curtain, and the machine’s stopping performance.

OSHA has a set of regulations for light curtains that are listed here:
1. The machine must be able to stop the movement of the ram anywhere in the stroke.
2. The stopping time of the ram must be known.
3. The stopping time of the ram must be monitored for deviation in stopping time on each stroke.
4. The minimum distance the light curtains can be located to the pinch point must be known.
5. The light curtains must be control reliable.
6. The machine stop circuit with which the light curtains are interfaced, must be control reliable.
7. The light curtains must be self checking for proper operation on each stroke.
8. There should be no easy way to disable the safety system without special tools.
9. If the safety system is disabled there should be a clear indication that it is disabled.
10. The operator and setup person should be properly trained in the operation of the safety system.

LASER FOCUSED ON SAFETY
The newest entry into the press brake safety category is probably its most revolutionary, the Laser Active Optic Protective Device, more commonly referred to as the AOPD. Four manufacturers now make AOPD systems including LazerSafe™ a partner of Rockford Systems. Inclusion of Laser AOPD technology in the B11.3 is a welcome addition to the standard that now gives press brake manufacturers, dealers and users a clear guideline to implementing this technology safely. (B11.3 sub-clause 8.8.7 – Close Proximity Point of Operation AOPD Safeguarding Device)

The biggest advantage of AODP is that operators can hand-hold piece parts up close to the dies, while using a foot-switch to actuate the machine-cycle, which is almost impossible to safely accomplish using a light curtain. Another advantage is for larger piece parts with tall side-legs that would be difficult when using a vertically mounted light curtain for safeguarding. For those familiar with using light curtains, those two situations often require excessive “Channel Blanking” which “yes” allows for production of those parts, but often lets the hands and fingers to reach too close to the dies.

LIGHT CURTAINS or AODP?
Laser AOPD protects the point of hazard whereas light curtain systems restrict operator access to the point of hazard. Operators can hand-hold piece parts up close to the dies with AOPD, while using a foot-switch to actuate the machine-cycle. This is virtually impossible to safely accomplish using a Light Curtain. But that doesn’t make AODP perfect for every application. AOPD systems are well suited for applications such as box bending, bending with flanges, or where light curtain effectiveness is diminished due to excessive blanking or muting.

There are advantages and drawbacks to both systems. And we would stress that it is not an “either-or” situation between light curtains and AODP. The two can be used, and often are, on the same machine. Light curtains provide for die configurations that the AODP won’t handle like compound bends, for instance. This is done to ensure that safeguarding is provided for all die setups. For die setups where neither light curtains or AOPD can offer effective safeguarding, but the part can be fixture in place, that is it does not require hand-support, a two-hand control can be used for safeguarding.

The diagram below sums up the two systems.

How To Use a Guard Opening Scale

Point-of-operation barrier guards are essential safeguarding equipment for hazardous industrial processes and machinery such as presses, pumps, motors and drills. When properly installed the barriers prevent a person from placing any part of their body into the point of operation by reaching through, over, under or around the guards to access a hazard. However, because barrier guards are typically constructed out of materials such as wire mesh, expanded metal, rods, or hairpins, most have openings that present the potential for injuries if a person reached through them. As a result, whether the guard is fixed, adjustable, movable, or interlocked, any openings must be measured for compliance with Table O-10 of OSHA 29 CFR 1910.217 (Mechanical Power Presses), current ANSI/CSA standards, or International standard ISO 13857 to determine the safe distance from the hazard.

The critical role of measuring barrier openings falls on a simple but often misunderstood tool: the Guard Opening Scale. Also known as “gotcha sticks,” Guard Opening Scales mimic the human hand and forearm. Over the past 70 years they’ve proven to be the most accurate means of ensuring any opening in a barrier guard will not allow a hazardous zone to be accessed.

HISTORY OF THE GUARD OPENING SCALE
The history of the Guard Opening Scale dates back to 1948. It was then that Liberty Mutual Insurance, joined with the Writing Committee for the ANSI B11.1 Safety Standard on Mechanical Power Presses, engineered a stair-step shaped measurement tool to determine guard-opening size vs. guard distance to the nearest Point of Operation hazard. A rash of injuries to mechanical power press operators who reached through barriers and suffered lacerations, amputations and crushed limbs prompted Liberty Mutual’s actions. Although Guard Opening Scales were first designed for point of operation guards on mechanical power presses, they are now often used on other machines as well.

Originally, the recommended dimensions used for the scale were based upon “average-size hands,” which at the time were a woman’s size 6 glove. ANSI incorporated these dimensions from Liberty Mutual into its 1971 revision of the ANSI B11.1 safety standard for mechanical power presses. In 1995, however, a study entitled “A Review of Machine-Guarding Recommendations” was conducted by Donald Vaillancourt and Stover Snook of Liberty Mutual Research to establish whether the 1948 drawings were consistent with current hand size data, in particular as the data relates to women and minorities who have become more prevalent in manufacturing. Vaillancourt and Snook suggested several important modifications including moving the glove size from a woman’s size 6 to a size 4. Drawings from the study have been adopted in several current ANSI B11-series safety standards for machine tools as well as in the ANSI/RIA R15.06 safety standard for industrial robots and robot systems. OSHA in Table O-10 of OSHA 29 CFR 1910.217 did not, on the other hand, officially adopt the drawings.

OSHA VS. ANSI GUARD OPENING SCALES
OSHA Compliance Officers are usually limited to using OSHA’s own scale, which is referenced by CFR 1910.217, Table 0-10. The ANSI scale is more likely to be used by Insurance Loss Control Engineers in manufacturing plants where smaller hand sizes tend to dominate the employee population. Let’s look at the differences in the two designs:


Note that the OSHA scale locks on the 3rd stair-step on the entrance side, and that the tip of the scale does not reach the die, meaning the test is “passed” for that opening size at that distance away. Also note that the ANSI scale locks on the last stair-step on the entrance side, and that the tip of the scale goes past the die, meaning that the test is “failed” for that opening size at that distance away. That problem can be fixed in one of two ways; move the guard a little further away from the die, or make the adjustable guard opening a little smaller, or some combination of those two.

USING A GUARD OPENING SCALE
A Guard Opening Scale is a two-dimensional representative of an average sized finger, hand and arm. Of course, the human body is not two-dimensional but three-dimensional, thus making its correct use critically important. Follow these simple instructions for proper measurements.

First, place the scaled side perpendicular to the smallest dimension in a hole in the barrier guard material and attempt to insert it towards the hazard. If properly designed, the barrier guard will stop the tip from accessing the hazard area. When multiple openings of various sizes exist in a barrier guard, each must be tested with the tool. The maximum guard opening that OSHA allows is a 6-inch opening at 31.5 inches away. For most people that’s armpit to fingertip. Also, the openings should always be measured empty, not with any material in place. This is based on the logic that personnel may put a hand through the guard opening without material taking up a portion of the space. Remember that Safety Inspectors won’t cut a plant operator any slack because the guard happens to be adjustable. Adjustable guard openings must be measured the same as fixed guard openings.

Please call 1-800-922-7533 or visit rockfordsystems.com for more information.

Press Brake Safeguarding Basics

Press Brakes are currently a hot topic in the “Machine Safeguarding” arena. OSHA regulations consider press brakes to be a 1910.212 machine, saying to the employer; “one or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by point of operation, in-going nip points, rotating parts, flying chips, and sparks” … 1910.212 requirements are good place to start, but they leave out the details of exactly how to go about safeguarding any particular machine. Therefore, a reference to an ANSI Standard like B11.3 on press brakes is often used to identify specific safeguarding alternatives. ANSI B11.3 may however need some help from ANSI B11.19 on safeguarding methods, to provide a complete picture of how to go about protecting people.

Older press brakes, like those manufactured in the mid-1980’s and before, were mechanical (flywheel-type) machines, some of which are still in use today. Because the stopping times on mechanical press brakes are long, equally long light curtain safety-distances result, making that safeguarding device impractical in many cases.

Press brakes manufactured after the mid-1980’s are much more likely to be hydraulic. Hydraulic press brakes allow for a wider variety of safeguarding options than mechanical press brakes do, and offer faster stopping-times, resulting in closer safety-distances where light curtains or two-hand controls are used.

A common method of safeguarding press brakes is with a vertically mounted infra-red light curtain. Hydraulic press brakes allow for short stopping times so that a light curtain can be mounted relatively close to the dies.

Two-hand controls on press brakes are often used in the sequence-mode of operation where the actuators bring the machine down and stop before the dies close, allowing just enough die-space to feed the part. The part is placed in the remaining die-opening, then a foot-switch is used to make the bend and return the machine to its full-open position.

Safety distance is required for both light curtains, and two-hand controls. That distance must be calculated with a stop-time measurement (STM) device on a quarterly basis. STM readings must be documented to show safety inspectors.

ANSI B11.3 which was updated in 2012, offers two completely new categories of protection for hydraulic press brakes: Active Optical Protective Devices (lasers) and Safe Speed Safeguarding. Active Optical Protective Devices (AOPDs) detect hands and fingers in a danger area. The biggest attraction for AOPDs are for jobs where the operator must hand hold small parts up close to the dies. A unique feature of AOPDs is that that they are designed to be mounted with zero safety distance, unlike light curtains that must be mounted at a calculated safety-distance, as outlined in ANSI B11.3. Safe Speed Safeguarding is based on a ram speed of 10mm per second or less, providing that speed is carefully monitored. Again, these two new methods of protection can only be applied to hydraulic press brakes (and potentially Servo-Drive Press Brakes).

The Lazersafe® Sentinel Plus is the most advanced guarding solution available designed specifically for hydraulic press brakes. The Lazersafe ties directly into the machine’s existing hydraulic and electric control circuits, providing a Category 4 solution. The Lazersafe is CE rated and allows machine operators to hold workpieces within 20mm of the point of operation. Encoder feedback ensures that the speed and position of the tooling is continuously monitored, and a 4.3” HMI provides machine operators immediate feedback of all vital functions. The Lazersafe Sentinel Plus is compatible with a wide variety of machines and tooling types, material thickness and easily allows for box shapes to be formed.

The backs of press brakes cannot be left wide open. Two hazards exist often exist here. The first is reaching the dies from the back. The second is 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. The very least, an awareness barrier, like a railing, chain, or cable with a “Danger” or “Warning” sign, complete with Pictograms, not just verbiage. (see photo)

For local OSHA interpretations that won’t accept awareness barriers, a full perimeter guard may be the answer for the back of a press brake. That guard can either be bolted into position, or if it’s movable, an electrical interlock switch can be installed to make sure it stays closed.

As with any industrial machine, Lockout/Tagout on Press Brakes must strive for “Zero Energy State” to and within each piece of equipment using both locks and tags.

Also mentioned in the ANSI standard is die safety blocks; please see our related blog post on “Demystifying Die Safety Blocks”.

Please call 1-800-922-7533 or visit rockfordsystems.com for more information.