Necessities in Robotic Safety SystemsDon’t integrate without itBy KC Roboticswww.kcrobotics.comApril 2013
We hear you. There are so many rulesthat if you implemented them all, youwouldn’t be able to run your robots.
We hear you. There are so many rulesthat if you implemented them all, youwouldn’t be able to run your robots.BUT…
We hear you. There are so many rulesthat if you implemented them all, youwouldn’t be able to run your robots.Kenji Urada was killed by a robot on a production line when anotheremployee turned the robot on while Urada was doing maintenance.Robert Williams died in 1979 when a robot arm hit him in thehead after he climbed into a part bin to retrieve some parts.
We hear you. There are so many rulesthat if you implemented them all, youwouldn’t be able to run your robots.Kenji Urada was killed by a robot on a production line when anotheremployee turned the robot on while Urada was doing maintenance.Robert Williams died in 1979 when a robot arm hit him in thehead after he climbed into a part bin to retrieve some parts.You can’t run your assembly line without people.
FACT: A robot’s arm will win in an arm wrestlingcontest with you.
FACT: A robot’s arm will win in an arm wrestlingcontest with you.FACT : A robot can and will pin and/or crush youagainst other objects.
FACT: A robot’s arm will win in an arm wrestlingcontest with you.FACT : A robot can and will pin and/or crush youagainst other objects.FACT : Hazards boil down to human error,equipment failure, and environmental conditions.
Studies have shown that accidentsinvolving industrial robotics do not usuallyoccur during normal working hours, ratherduring times of installation, maintenance,programming, and servicing.http://www.osha.gov/SLTC/robotics/
Here’s a short guide as to how you cankeep your employees fromexperiencing the same fatesas Kenji and Robert.
Workers performing service or maintenance on machinery and equipment maybe exposed to injuries from the unexpected energization, startup of the machinery orequipment, or release of stored energy in the equipment.The Lockout/Tagout standard requires the adoption and implementation ofpractices and procedures to shut down equipment, isolate it from its energy source(s),and prevent the release of potentially hazardous energy while maintenance andservicing activities are being performed. It contains minimum performancerequirements, and definitive criteria for establishing an effective program for thecontrol of hazardous energy. However, employers have the flexibility to developlockout/tagout programs that are suitable for their respective facilities.This tutorial summarizes for you the key components of the standard in aquestion/answer format. This tutorial is intended to guide the user in understandingaspects of the Lockout/Tagout standard. It is not to substitute for compliance with theplain terms of the standard. Nothing in this tutorial is intended to diminish orotherwise affect OSHAs authority to enforce the requirements of 29 CFR 1910.147 orof the OSH Act, nor is it intended to create any legally enforceable right or benefit inany person. OSHA.gov.OSHA Standard Number 1910.147The control of hazardous energy(lockout/tagout)http://www.osha.gov/pls/oshaweb/owasrch.search_form?p_doc_type=INTERPRETATIONS&p_toc_level=2&p_keyvalue=1910&p_status=CURRENT
That’s a lot of words. Try this:Identify – What is the energy source? Electrical, Hydraulic,Pneumatic, the list goes on, and some machines have morethan one source.Isolate- Disconnect all power sources from the robot.Secure- Lock the energy source so that no one can comebehind you and flip a switch. Only you can have a key to thelock. If you also have tags, place tags with the lock. Your nameshould be on the tag and only you are allowed to remove thetag.Validate – Are you sure the robot is isolated? How are yousure? Always check.
Four words. Much Better.Identify. Isolate. Secure. Validate.
Four words. Much Better.Identify. Isolate. Secure. Validate.Why is this integral to any system?
If you cut off the power supplies of therobot, there is no chance for the robot toinadvertently move due to human error ormachine malfunction.Also, power supplies many times containenough voltage to kill a person in seconds,if the power source is removed from therobot before maintenance, the chances ofinjury directly from the power supply areeliminated.
Interlocked DoorsInterlocked doors are seen on safety fencing that is typicallyinstalled around the predetermined work envelope of arobotic system.The electromechanical switch is normally found on hinges oron the doors themselves. When the interlock is tripped, therobot will cease function.The interlock can be disabled with a key when the robot issafely disengaged.
Light CurtainsMostly used around robotic systems that need frequent accessibility bythe operator, light curtains are extremely reliable for detectingunplanned movement within predetermined spaces near a robot. In anutshell it’s an invisible wall of light that, when broken, will stop therobot in motion.How it works:- A transmitter located on metal posts around the robotic systemoutputs a synchronized pattern of infrared light beams to a receiveron an opposing post, hence, curtain of light.- The receiver is only programmed to acknowledge these beamspreventing an external, unintended light source from interfering.- When a beam is broken, the work cell is shut down, the robot’s brakesare enabled and the work cell cannot move again until restarted.http://www.lightcurtain.com/light_curtain-operation.html
Warning LightsWarning lights are exactly what they say they are. Theyare lights, usually mounted on the top of the safetyfencing or the PLC and indicate to those workingaround the robot if the system is operating safely.The colors of the lights are usuallyred, yellow, and green.
Cable ManagementCable management is a common issue amongst assembly lines. From atop therobot to the cables running on the floor, torn, cut, or damaged cablescan cause hazardous situations for everyone on the assembly line.www.hoffmanonline.comwww.igus.com
Cable ManagementCable management is a common issue amongst assembly lines. From atop therobot to the cables running on the floor, torn, cut, or damaged cablescan cause hazardous situations for everyone on the assembly line.www.hoffmanonline.comwww.igus.comSome tips on how to make cables last a lifetime:- Make sure the cables being installed fit the application, many cablesare not fit for welding applications and can wear quicker- Cables on the robot can easily be contained by a sleeve or cablemanagement system. Companies like igus offer retractable andflexible cables for the robot and Hoffman offer cable managementthroughout the system.- A common reason for replaced cables? Fork Lifts and foot traffic overthe cables. Protect your cables from plug to plug.
Remote E-StopsVary from manufacturer to integrator, make sure the technician installingthem teaches you and your operators how to engage them.Found on the teach pendant, around the robotic system and anywhere itis presumed an operator may need to go to operate the robot.Usually are big red buttons placed in obvious places around the roboticsystem.Not the equivalent of a lockout/tagout (ie: Hazardous Energy ControlProcedure). They are considered more of a preventive measure.To restart after pulling E-Stop, operator must apply a“power ON”or“RESET”button on the robotic system.
Smoke Hoods/Fume ExtractorsWhile what you can see is dangerous, what you can’t see can be just ashazardous to your health. When arc welding, fumes are created that cancause a lot of health problems if inhaled. To protect against these fumes,companies involved with robotic AND manual arc welding should investin a fume extraction system.Fumes are created during the welding process when some of the weldedmetal particles are released into the air.Fume extractors can be portable or stationary and some can be installedindoors as well as outdoors.http://www.asse.org/practicespecialties/articles/weldingfumes.php
http://www.asse.org/practicespecialties/articles/weldingfumes.phpWelding fumes can havelong and short-term effects on the:- Lungs- Brain cells- Nervous system
http://www.asse.org/practicespecialties/articles/weldingfumes.phpWelding fumes can havelong and short-term effects on the:- Lungs- Brain cells- Nervous systemProblems that have been documented include:- Encephalopathy- Fatigue- Mental confusion- Metal fume fever- Paralysis
SoftwareMost OEMs carry their own branded software now that addssafety mechanisms to their robots.KUKA Robotics, for example, offers KUKA.,SafeOperationsoftware to maximize safety when the robot is in use.The software allows an integrator to configure a safe zone forthe robot by defining the cell area, the envelope that therobot will be working in, the product area and the product ,and the robot itself.The software is intended to limit the area in which the robotcan move reducing the distance an employee may need tobe from the robot. This especially benefits manual loadingstations.www.kuka-robotics.com/usa/en/products/software/hub_technologies/start.htm