Machine Safety
When designing safeguarding systems for machines, one of the basic building blocks is the movable guard — doors, panels, gates or other physical barriers that can be opened without using tools. Every one of these guards needs to be interlocked with the machine so that the hazards covered by the guards are effectively controlled when the guard is opened. There are a number of important aspects to the design of movable guards. This article will focus on the selection of interlocking devices that are used with movable guards. The hierarchy of controls This article assumes that a risk assessment has been done as part of the design process. If you haven’t done a risk assessment, start there, and then come back to this point in the process.The hierarchy of controls describes levels of controls that a machine designer can use to control the assessed risks [1]. Designers are required to apply every level of the hierarchy in order, starting at the top. Where a level cannot be applied, the designer moves to the next lower level.Though much emphasis is placed on the correct selection of these interlocking devices, they represent a very small portion of the hierarchy. It is their widespread use that makes them so important when it comes to safety system design. Electrical versus mechanical interlocksMost modern machines use electrical interlocks because the machine is fitted with an electrical control system, but it is entirely possible to interlock the power to the prime movers using mechanical means. This doesn’t affect the portion of the hierarchy involved, but it may affect the control reliability analysis that you need to do.CategoriesIn Canada, CSA Z432 [2] and CSA Z434 [3] provide four categories of control reliability: simple, single channel, single channel monitored and control reliable. In the U.S., the categories are very similar, with some differences in the definition for control reliable. In the EU, there are five levels of control reliability, defined as Performance Levels (PL) in ISO 13849-1: PL a, b, c, d and e [4]. Underpinning these levels are five architectural categories: B, 1, 2, 3 and 4. To add to the confusion, IEC 62061 [5] is another international control reliability standard that could be used. This standard defines reliability in terms of Safety Integrity Levels (SILs). These SILs do not line up exactly with the ISO 13849-1 PLs, but they are similar. IEC 62061 is based on IEC 61508 [6], a control reliability standard used in the process industries. IEC 62061 is not well suited to applications involving hydraulic or pneumatic elements.The North American architectures deal primarily with electrical or fluid-power controls, while the EU system can accommodate electrical, fluid-power and mechanical systems.From the single channel monitored or Category 2 level up, the systems are required to have testing built-in, enabling the detection of failures in the system. The level of fault tolerance increases as the category increases. Interlocking devicesInterlocking devices are the components that are used to create the interlock between the safeguarding device and the machine’s power and control systems. Interlocks can be purely mechanical, purely electrical or a combination of these.Most machinery has an electrical/electronic control system, and these systems are the most common way that machine hazards are controlled. Switches and sensors connected to these systems are the most common types of interlocking devices.Interlocking devices can be something as simple as a micro-switch or a reed switch, or as complex as a non-contact sensor with an electromagnetic locking device.Requirements for these devices are published in a number of standards, but the key ones for industrial machinery are ISO 14119 [7, 2], and ANSI B11.0 [8]. These standards define the electrical and mechanical requirements, and in some cases the testing requirements, that devices intended for safety applications must meet before they can be classified as safety components.These devices are also integral to the reliability of the control systems into which they are integrated. Interlock devices, on their own, cannot meet a reliability rating above ISO 13849-1 Category 1, or CSA Z432-04 Single Channel. To understand this, consider that the definitions for Category 2, 3 and 4 all require the ability for the system to monitor and detect failures, and in Categories 3 and 4, to prevent the loss of the safety function. Similar requirements exist in CSA and ANSI’s “single-channel-monitored,” and “control-reliable” categories. Unless the interlock device has a monitoring system integrated into the device, these categories cannot be achieved. Environment, failure modes and fault exclusionEvery device has failure modes. The correct selection of the device starts with understanding the physical environment to which the device will be exposed. This means understanding the temperature, humidity, dust/abrasives exposure, chemical exposures, and mechanical shock and vibration. Selecting a delicate reed switch for use in a high-vibration, high-shock environment is a recipe for failure, just as selecting a mechanical switch in a dusty, corrosive environment will also lead to premature failure.The device standards do provide some guidance in making these selections, but it’s pretty general.Fault exclusion is another key concept that needs to be understood. Fault exclusion holds that failure modes that have an exceedingly low probability of occurring during the lifetime of the product can be excluded from consideration. This can apply to electrical or mechanical failures. Here’s the catch: Fault exclusion is not permitted under any North American standards at the moment. Designs based on the North American control reliability standards cannot take advantage of fault exclusions. Designs based on the international and EU standards can use fault exclusions, but significant documentation supporting the exclusion of each fault is needed. Defeat resistanceThe North American standards require that the devices chosen for safety-related interlocks be defeat-resistant, meaning they cannot be easily fooled with a cable-tie, a scrap of metal or a piece of tape.The International and EU standards do not require the devices to be inherently defeat-resistant, which means that you can use “safety-rated” limit switches with roller-cam actuators, for example. However, as a designer, you are required to consider all reasonably foreseeable failure modes, and that includes intentional defeat. If the interlocking devices are easily accessible, then you must select defeat-resistant devices and install them with tamper-resistant hardware to cover these failure modes.Almost any interlocking device can be bypassed by a knowledgeable person using wire and the right tools. This type of defeat is not generally considered, as the degree of knowledge required is greater than that possessed by “normal” users. Device selectionWhen selecting an interlocking device, start by looking at the environment in which the device will be located. Is it dry, wet or abrasive? Is it indoors or outdoors and subject to temperature variations?Is there a product standard that defines the type of interlock you are designing? An example of this is the interlock types in ANSI B151.1 [4] for plastic injection moulding machines. There may be restrictions on the type of devices that are suitable based on the requirements in the standard.Consider integration requirements with the controls. Is the interlock purely mechanical? Is it integrated with the electrical system? Do you require guard locking capability? Do you require defeat resistance?Once you can answer these questions, you will have narrowed down your selections considerably. The final question is: What brand is preferred? Go to your preferred supplier’s catalogues and make a selection that fits with the answers to the previous questions.The next stage is to integrate the device(s) into the controls, using whichever control reliability standard you need to meet. That is the subject of another article!References[1] Safety of machinery - General principles for design - Risk assessment and risk reduction, ISO Standard 12100, Edition 1, 2010[2] Safeguarding of Machinery, CSA Standard Z432, 2004 (R2009)[3] Industrial Robots and Robot Systems - General Safety Requirements, CSA Standard Z434, 2003 (R2008)[4] Safety of machinery — Safety-related parts of control systems — Part 1: General principles for design, ISO Standard 13849-1, 2006[5] Safety of machinery – Functional safety of safety-related electrical, electronic and programmable electronic control systems, IEC Standard 62061, Edition 1, 2005[6] Functional safety of electrical/electronic/programmable electronic safety-related systems (Seven Parts), IEC Standard 61508-X[7] Safety of machinery – Interlocking devices associated with guards – Principles for design and selection, ISO Standard 14119, 1998[8] American National Standard for Machines, General Safety Requirements Common to ANSI B11 Machines, ANSI Standard B11.0, 2008 Douglas Nix, A.Sc.T., is managing director at Compliance InSight Consulting, Inc. ( in Kitchener, Ont. He produces a blog and podcast called Machinery Safety 101, exploring a wide variety of machine safety topics. Check out his blog at column originally appeared in the May 2012 issue of Manufacturing AUTOMATION.
In North America, about five to 10 arc flash events occur each day. Arc flashes are responsible for as many as 80 percent of all electrical-related injuries.
An increased focus to comply with regulations and the need to reduce safety injuries are driving organizations to adopt new strategies and technologies to ensure the safety of people, processes and products. A recent Aberdeen Group study, "Integrated Safety Systems: Ensuring Safety and Operational Productivity," surveyed more than 120 executives last Fall about the current state of their safety program and the technologies they use to support their safety initiative. The report provides a roadmap for organizations attempting to better understand how an integrated safety system and other enabling technologies can best be deployed in a plant environment.
Bill 160 shifts the responsibility for injury and illness prevention activities from the Workplace Safety and Insurance Board (WSIB) to the Ministry of Labour. This will have the Ministry of Labour carry out health and safety inspections at Ontario workplaces, as well as oversee the delivery of workplace injury and illness prevention services by Ontario's health and safety associations. I had a chance to speak with the Ministry of Labour's John Vander Doelen, director of the Occupational Health and Safety System Review Project Secretariat, about how this shift will impact the readers of Manufacturing AUTOMATION (MA).
Note to readers: This article focuses on item 2 of the table in section 7 of the regulations titled Pre-Start Health and Safety Review that deals with machinery. The guidelines from the Ministry of Labour are available at
Today, machines operate at considerably higher speeds than in the past. In the race to meet production deadlines and budgets, safety cannot be forgotten.
As a controls integrator, I have had the opportunity to work in different facilities across the globe. The majority of these facilities have one thing in common - the concept of arc flash is largely an unknown. This is no surprise, as arc flash standards and awareness have only recently become publicized and enforced.
When a company is convicted of an offence under Ontario's Occupational Health and Safety Act, the normal penalty imposed by the court is a fine. The courts in Ontario consider a wide range of factors when sentencing a corporation under the Act, although these factors are not of even weight.
Most offences under occupational health and safety legislation are "strict liability offences." This means that if a person or company is charged with such an offence, the Crown only has to prove that a workplace accident or injury took place due to a prohibited act or omission. The Crown does not have to prove that the defendant was at fault or negligent. However, the defendant — usually the employer — can defend itself against a strict liability offence by establishing the defence of due diligence.
There are a number of myths that have grown up around emergency stops over the years. These myths can lead to injury or death, so it's time for a little myth busting.
Manufacturers across many industries are placing increased emphasis on machine designs that support safety and sustainability initiatives, and drive economic prosperity. Machines that improve safety, minimize waste, consume less energy and deliver maximum return on investment are critical to the success of any sustainable production program. Building such a machine requires a holistic approach to analysing operational efficiency, safety, functionality, productivity, ease of operation and maintenance. By following these five best-practice design principles, machine builders can deliver safer, more cost-effective and sustainable machines. 1. Perform a safety audit after mechanical design, but before control system design: Performing a safety audit before control system design helps engineers chart the course for an effective safety solution, and evaluate and investigate risks early in the development process. This saves critical time and helps machine builders get their equipment to market faster. In addition, the machine's end users gain optimized production, thanks to an automation system that helps operate machinery and processes in the most efficient way. A safety audit identifies the required safety control system integrity level and helps guide the selection of the overall control architecture to achieve the optimum level of safety. 2. Guard or control access to moving parts: Where hazards cannot be removed through design, machine builders typically will install a fixed physical barrier that protects users from the hazard. When frequent access to the hazardous area is required, non-fixed guards are used, such as removable, swinging or sliding doors. In areas where non-fixed guards are impractical, guarding solutions that monitor the presence of the operator rather than the status of the gate can be used.   While relays and other devices prove effective, many safety applications require a level of programming or more sophisticated safety logic that is best met through a safety controller. Safety controllers offer significant benefits in multistep shutdown or ramp-down sequences, such as transfer line applications, because they provide the necessary logic through software rather than the hard-wired logic of relays. An integrated safety controller is an ideal solution for any application requiring advanced functionality, such as zone control. With properly designed safety controls and guarding, designers reduce access time and help to make machines safer and more efficient. 3. Use integrated safety systems to reduce control system complexity: The more designers integrate the standard and safety control functions of a system, the better the opportunity is to reduce equipment redundancies and improve productivity and economic factors. This integrated control functionality reduces the number of unique components in use on the factory floor, which in turn reduces crib inventory costs, as well as maintenance team training requirements. End users also benefit from less waste with fewer parts to maintain and replace throughout the machine life cycle. In addition, integrated control systems have broader intelligence regarding machine operation and status, and reduce nuisance shutdowns and prolonged restarts, further improving machine efficiency and productivity. New safe-speed control solutions provide a great example of effective control integration. With safe-speed control, safety input devices, such as guard-locking switches, light curtains and emergency stops, connect directly to the speed-monitoring core of the control solution. This eliminates the need for a separate, dedicated safety controller. Providing use across multiple platforms, safe-speed control solutions help reduce overall system cost and improve flexibility because they allow operators to perform maintenance and other tasks while a machine is in motion. Safe-speed control also helps increase uptime and decrease energy costs because a machine does not need to be completely shut down and restarted. Networking offers another way to integrate safety and standard controls. The introduction of networks to the plant floor brought many benefits to manufacturers, including increased productivity, reduced wiring and installation, improved diagnostics and easier access to plant-floor data. Using an existing network to include safety information extends those same benefits, allowing seamless communication of the complete automation process on one standard network with one set of hardware and wiring. 4. Make better use of diagnostics: With the ability to embed intelligence-gathering devices into machines without redesign or retooling, machine builders provide customers with self-diagnostic equipment capable of predicting and preventing failures, thereby boosting productivity and reducing repair costs. Moreover, this technology relays the machine condition information back to the machine builder for value-added monitoring and analysis services without compromising existing resources or hindering profitability. From the end user's perspective, turning the maintenance function over to the machine builder makes good business sense - it improves machine performance, maximizes capital investments and allows for more cost-efficient use of internal resources.  Machines designed with EtherNet/IP connectivity allow remote troubleshooting and thus provide end users with improved diagnostic benefits. The ability to remotely monitor equipment from a distant location helps reduce fuel usage and related emissions, as well as associated travel time and costs of maintenance personnel who otherwise would go to the machine's location. 5. Design IT connectivity into the machine: Building information-enabled machines capable of connecting into an end user's IT infrastructure provides them with critical operational insight, including energy efficiency and overall equipment effectiveness (OEE) calculations. This insight, in turn, helps plant managers reduce waste and optimize productivity. A machine's IT connectivity also helps maximize the benefits of a machine's track-and-trace capabilities. Using advanced information software, manufacturers track and record relevant data at every step of the process to identify when and where resources were used. This visibility offers end users a wealth of data for waste reduction and other improvement programs. In addition, these systems also help automate track-and-trace procedures of product genealogy through the full chain of custody. In doing so, these systems help companies comply with regulations, document required data, identify potential product quality issues before they reach the market and, if necessary, respond to recalls faster and more efficiently. CONCLUSION Thanks to advancements in technology and best practices, machine builders can play an important role in helping companies implement safer machine designs that support sustainable production practices. By following the above core design principles and leveraging the best of today's advanced technologies, machine builders can create safer, more cost-effective and reliable equipment. Steve Ludwig is program manager for Rockwell Automation. For more information, please contact Leanne Hanson at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
The ISO 10218 international standard for industrial robot safety is entering its last stage of approval prior to publication. This decade-long effort by representatives from 10 countries over three continents will result in the first all-new and complete international robot safety standard since 1992. This milestone achievement will, in turn, put the effort to revise the current Z434 Canadian national standard for robot safety into high gear, and result in new published standards in 2011. Both ISO 10218-1 (the revision to ISO 10218-1:2006 for the robot only) and the completely new ISO 10218-2 for the robot system and integration, are being prepared for release as Final Draft International Standards (FDIS) and formal approval balloting. This process should be completed near the end of this year, with publication coming next year. The revision to the international standard draws heavily on the experience and success of the United States' robot safety standard, ANSI/RIA R15.06-1999 (r2009). Since the R15.06 and Z434 documents are very similar, the Canadian content in the international standard will also be recognized. The international standard has always been slanted towards instructions for the manufacturer. The Part 1 document that was revised and published in 2006 was dedicated solely to the robot manufacturer. It was basically the requirements that were contained in Clause 4 of the Z434, with some new features added. Important information for proper use of the robots was not included. Part 2 of the ISO document rounds out the necessary safety information for the robot system and the integration of robots into useful work cells. It essentially contains the rest of the Z434 information. The two documents together will give the international community the necessary information for proper robot safety. With the advent of a new international standard for robot safety, what is happening with the standards in North America? The simple answer is that both CSA- and RIA-sponsored standards development teams are preparing to revise the current standards (Z434 and R15.06). Canada has not made a change in its robot safety standard since publishing the Z434 in 2003. In 2007, the United States adopted the ISO 10218-1 as ANSI/RIA/ISO 10218-1-2007, but could not change R15.06 because the Part 2 ISO document was not complete at that time. The RIA team bridged the gap in user information relative to the new features in the ISO standard with a technical report - RIA TR R15.206-2008. The United States has the R15.06; the ISO 10218-1, which stands in for Clause 4; the technical report; and the other 13 clauses of R15.06. These make up a newer package of safety information. The same can be applied in Canada with the Z434, though the documents have not been formally adopted. Canada and the United States have spent a lot of time and resources supporting the revision to the international standard. We can now reap some of the rewards for that effort by adopting it as our standard. This means the ISO standard will represent one standard, valid worldwide, and recognize the global nature of industrial robot safety requirements and the industry itself. Robots and robot systems designed and built in other countries will be fully compliant with the North American requirements, and will be able to be used here in North America. This will correct a long-standing issue presented to a number of global companies with both North American and international operations. Likewise, robot systems designed in Canada will be compliant with the requirements in other countries if a company chooses to move a cell or wants common cell designs throughout its global corporate operations. How will this be achieved? For the United States, it will all be contained in one document - ANSI/RIA R15.06-2011. The R15.06 committee has been actively following the work of the international committee and making appropriate inputs and comments to their work as the standards develop. The R15.06 committee released the first draft of the next edition of R15.06 at the National Robot Safety Conference last month. The draft contains both parts of the ISO standards (Part 1 for the robot and Part 2 for robot systems and integration), and has additional U.S.-unique requirements directed to the user. The new standard thus will continue to address the three stakeholders that the current R15.06 standard addresses - the manufacturer, the integrator and the user. Similarly, the Z434 document will be revised to include the updated robot safety information. Work on that document is continuing and is expected for release in 2011. The new standards will represent the state-of-the-art for industrial robot safety and robot work cell efficiency and productivity. North America promises to stay at the leading edge of robot safety technology, while making our industry more efficient and competitive. Jeff Fryman is the director of Standards Development at the Robotic Industries Association. He can be reached at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
In Canada, and North America as a whole, the standards surrounding machine safety - particularly from a mechanical focus - are rather muddy. While the Occupational Health and Safety Act (OSHA) ensures the protection of workers from injury while on the job, and the Canadian Standards Association (CSA) has established the Safeguarding of Machinery standard Z432-04, which assigns responsibilities for the proper safeguarding of machinery, there are currently no standards that address mechanical machine safety, such as forced control (including contours and cams), and pneumatics and hydraulics in an automated system. While Europe has its own set of standards, North American manufacturers are left only with a standard developed by the International Electrotechnical Commission (IEC), the IEC61496, which is an international standard for all electrical, electronic and related technologies that is accepted as the default standard by the Underwriters Laboratories. But just because there aren't defined Canadian standards doesn't mean owners of manufacturing equipment aren't responsible for malfunctioning or harmful machines. In the past decade, there has been increased regulation and enforcement by the Ministry of Labour on machine guarding and safety, particularly regarding machinery and operator interfaces. In many cases, it's the owners of these machines - not the designers or manufacturers - that face hefty fines and potential jail time if an employee becomes injured on the job as a result of them. Over the past few years, there has been a steady increase in the penalties available under provincial legislation relating to health and safety, and this trend seems to be on the rise. This has led to a push to ensure machines are safe before they're built - namely in the design stage. This trend appears to be driven by customers who will evidently be held responsible for any risks that could become a safety concern during a pre-start safety inspection or through the lifespan of a piece of automated equipment.  This is a good place to start. To prevent potential penalties down the road, it's wise for buyers of automation machinery to ensure that, during the design of new machinery and the upgrade of existing machinery, measures are implemented to protect the worker and machine from moving devices through security and interlocking principles.  The problem is, this stage of the process is identified through a thorough risk assessment, which is nothing more than a calculated forecast of possible recognized risks and severity of injury. The individual phases of a machine's life present different hazards, which would not be evident through a normal operating risk assessment. A thorough assessment should also consider the following factors: • Initial position standstill: What are the potential hazards when machinery is pressurized for the first time from a pre-exhausted state? • Set up and service operation: What are the associated risks when machinery needs to be set up and serviced? What are the potential hazards that may exist when compressed air and/or power have been shut off?  • Emergency: The emergency condition can present different hazards, such as losing control of motors and drives that continue to move under momentous forces when an emergency event has been triggered. How will your machinery respond to emergencies? Safe stopping, safe exhausting and protection against unexpected startup need to be considered when an emergency condition has been triggered.  In all of these phases, there is the need for risk assessment and the identification of hazards. This results in design measures that reduce risk, and technical protective measures that will ensure that the residual risk is at an acceptably low level.  The life expectancy of machinery also needs to be addressed, and mean time to failure calculations should be carried out to determine that the components that are used in critical applications will perform as required during the life cycle of machinery. Rick Sauer is a product manager with Festo Inc. He can be reached at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Ask any production line manager about the importance of safety, and they will likely tell you about the critical role it plays in helping to protect personnel, reduce injuries and meet compliance demands. These are all valid objectives, but manufacturers and machine builders are missing opportunities if they only focus on avoiding negative consequences, rather than striving for increased productivity, improved competitiveness and overall profitability as well.  Historically, the industry has viewed safety practices as punitive actions or compliance activities, not as opportunities to deliver real value or gain a competitive edge. These days, however, manufacturers understand that a well-designed safety system can help improve their efficiency and productivity, and machine builders increasingly recognize how safety systems can improve both business and machine performance, helping differentiate themselves to potential customers. The combination of functional safety standards, new safety technologies and innovative design approaches are positioning safety as a core system function that can deliver significant business and economic value. This includes financial returns beyond the benefits of reducing costs associated with accidents and medical expenses. A systematic approach To achieve a higher level of functional safety and experience the resulting benefits, system designers must have an in-depth understanding of the manufacturing process and a clear determination of machinery limits and functions, as well as a thorough knowledge of the various ways that people interact with the machinery. They also need to take a practical, rigorous approach to safety system design and be willing to implement and apply new safety technologies and techniques. The functional safety life cycle, as defined in standards IEC 61508 and IEC 62061, provides the foundation for this detailed, more systematic design process for machinery applications. A key objective of the safety life cycle is addressing the cause of accidents. To do this, designers must aim to create a system that helps to reduce and minimize risks, meets appropriate technical requirements and helps assure personnel competency. Previous standards have relied on prescriptive measures defining specific safeguarding. The new functional standards are performance-based, which makes it easier for designers to quantify and justify the value of safety. This approach uses a more methodical, deterministic approach, and offers the ability to tailor the specific safety functions to the application. It helps to reduce cost and complexity, improve machine sustainability, and achieve a more optimum level of safety for each defined safety circuit or function to improve the return on investment. Safety life cycle phases Conducting a risk assessment is the first phase of the safety life cycle. A risk assessment provides the basis for the overall risk reduction process, which involves the following steps: * Eliminating hazards by design using inherently safe design concepts; * Employing safeguarding and protective measures with hard guarding and safety devices; * Implementing complementary safety measures, including personal protective equipment (PPE); and * Achieving safer working practice with procedures, training and supervision. When designing a safety system, a risk assessment helps to determine what potential hazards exist, and which safety mechanisms should be implemented to help ensure adequate protection against them. The functional life cycle provides the framework for several highly effective "design-in" safety concepts. These include passive, configurable and lockable system designs. Easier and more intuitive A passive approach aligns with the design philosophy that safety systems should be easy to use and not hinder production. The reason that operators might elect to bypass safety systems is that the systems are cumbersome or impractical or do not easily accommodate maintenance and operating procedures. An effective passive system design performs its function automatically, with little if any effort required on the part of the user. Moreover, when intelligently applied, a passive design can help boost productivity. For example, in many production operations, manufacturers often use a light curtain to help prevent machine motion when an operator enters a hazardous area. Other approaches, such as a safety interlock gate, require operators to perform a task to initiate the safety function. Even if it only takes 10 seconds to open and close the gate for each cycle, that time accumulates over the course of a 200-cycle day. With a light curtain, the operator simply breaks the infrared barrier when entering hazardous areas, and the operation comes to a safe stop. Over time, this passive design helps to increase productivity and creates a positive return. Another approach that helps limit exposure to hazards and reduces the incentive to bypass the safety system is a configurable design, which allows operators to alter the behaviour of the safety system based on the task they need to perform. For example, in many cases, an operator may need to access a machine and still need some form of power enabled to perform a maintenance function, clear a jam or teach a robot. The initial risk assessment identifies and defines all the tasks, including these, that must be performed on the machine with or without power. The assessment offers insight to create a configurable design that meets global safety requirements, increases productivity and reduces the incentive to bypass the system. In most cases, inexpensive components, like push buttons, selector switches and lights, are all that is needed to achieve an acceptable level of safety.  Turning safety into productivity Using a lockable system design to systematically reduce mean time to repair (MTTR) can help boost productivity. This approach allows operators to select a safety configuration, and then lock it in place at the point of entry. In addition to helping to protect configuration changes, a lockable design also helps to achieve higher productivity by using the safety system in lieu of lock-out/tag-out (LO/TO) for many routine maintenance and set-up procedures. For example, in a LO/TO situation, operators may need to use six locks to safely shut down a line, including electronic, pneumatic and robotic systems. Shutting down the entire machine can be time-consuming and inefficient, causing excessive downtime that hinders productivity. If the safety system meets the target safety level and complies with standard ANSI Z244-1, the safety system can be used to disable the hazards. In this case, LO/TO is not required. Instead of locking the disconnect switch, operators only lock the safety system. The potential cost savings associated with reducing the LO/TO downtime by even a few minutes often proves to be substantial. For example, let's say a manufacturer is able to reduce MTTR by two minutes using this lockable design approach. If the value of one minute of downtime is $10,000, and the plant averages 3,000 downtime events per year (eight per day), the value of the safety solution equates to roughly $60 million per year ($10,000 X two minutes X 3,000). The far-reaching economic benefits of a well-designed safety system are too significant to overlook. Using reliable safety technology and the rigorous approach defined in the safety life cycle, manufacturers and machine builders can harness the inherent value of intelligent safety system designs to help drive productivity, reduce labour costs and ultimately increase the bottom line. George Schuster is a senior industry consultant, Safety and Sustainability Solutions, with Rockwell Automation.
Proper machine guarding is a safety precaution that shouldn't be taken lightly. That was the underlying message at the Machine Automation Safety Congress, which was held from May 4 to 5 at the International Centre in Mississauga, Ont. The show was one of four safety-related conferences taking place under one roof and was accompanied by the IAPA's Partners in Prevention, Your Workplace 2010, and CANECT 2010. The MASC portion of the conference featured 11 machine automation safety and safe-guarding exhibitors, as well as a panel discussion on machine safety. The panel discussion, which was mediated by Andre Voshart, former editor of Manufacturing AUTOMATION, and Mari-Len De Guzman, editor of MA's sister publication, Canadian Occupational Safety, featured four panelists: Jeremy Warning of Heenan Blaikie, Wayne De L'Orme of the Ontario Ministry of Labour, Walter Veugen of Veugen Integrated Technologies, and John Murphy of Leuze Electronics. Each speaker addressed a different aspect of machine safety to a packed house, starting with Wayne De L'Orme who offered a unique insight into the severe ramifications of improper machine guarding. Of the 78,000 orders the Ministry of Labour filed in 2009, 4,000 were violations of sections 24 and 25 which are industrial regulations. "Machine guarding issues were the number one cause of fatalities in the industrial sector last year," he said. "They were also the number one source of prosecution." Jeremy Warning presented the legal motivation behind proper machine guarding. "For every $100,000 in fines, you'll end up paying $25,000 in payables," he said. To put that number into perspective, he presented a number of cases where companies not only lost employees due to a lack of proper machine guarding, but were hit hard by fines as well. The most notable was an October 2003 ruling that saw the Ontario Power Generation pay $350,000 in fines after a fatal accident that saw an employee get caught in a conveyor due to a guarding violation. John Murphy walked attendees through an effective safety audit. He suggested a five-step process - research, delegate, evaluate, plan and prepare. He also recommended getting everyone involved. "Who should be involved? The operator? Definitely. Otherwise they'll find a way to get around the safety guard," he said. "You need to get the operator's buy-in." Walter Veugen supported that notion and suggested getting companies like his, which offer guarding solutions, involved before the audit takes place. "Sure, we can come in after the audit and fix problems then and there, but what about the next one?" he said. "What we try to do is help companies identify what a guarding problem is so they can prevent an accident at an earlier stage." Vanessa Chris is the acting editor of Manufacturing AUTOMATION.
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