Necessities in Robotic Safety Systems Don’t integrate without it

By KC Robotics www.kcrobotics.com

April 2013

We hear you. There are so many rules that if you implemented them all, you wouldn’t be able to run your robots.

We hear you. There are so many rules that if you implemented them all, you wouldn’t be able to run your robots.

BUT…

We hear you. There are so many rules that if you implemented them all, you wouldn’t be able to run your robots.

Kenji Urada was killed by a robot on a production line when another employee turned the robot on while Urada was doing maintenance.

Robert Williams died in 1979 when a robot arm hit him in the head after he climbed into a part bin to retrieve some parts.

We hear you. There are so many rules that if you implemented them all, you wouldn’t be able to run your robots.

Kenji Urada was killed by a robot on a production line when another employee turned the robot on while Urada was doing maintenance.

Robert Williams died in 1979 when a robot arm hit him in the head 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 wrestling contest with you.

FACT: A robot’s arm will win in an arm wrestling contest with you.

FACT : A robot can and will pin and/or crush you against other objects.

FACT: A robot’s arm will win in an arm wrestling contest with you.

FACT : A robot can and will pin and/or crush you against other objects.

FACT : Hazards boil down to human error, equipment failure, and environmental conditions.

Studies have shown that accidents

involving industrial robotics do not usually

occur during normal working hours, rather

during times of installation, maintenance,

programming, and servicing.

http://www.osha.gov/SLTC/robotics/

Here’s a short guide as to how you can keep your employees from

experiencing the same fates as Kenji and Robert.

Workers performing service or maintenance on machinery and equipment may be exposed to injuries from the unexpected energization, startup of the machinery or equipment, or release of stored energy in the equipment.

The Lockout/Tagout standard requires the adoption and implementation of practices and procedures to shut down equipment, isolate it from its energy source(s), and prevent the release of potentially hazardous energy while maintenance and servicing activities are being performed. It contains minimum performance requirements, and definitive criteria for establishing an effective program for the control of hazardous energy. However, employers have the flexibility to develop lockout/tagout programs that are suitable for their respective facilities.

This tutorial summarizes for you the key components of the standard in a question/answer format. This tutorial is intended to guide the user in understanding aspects of the Lockout/Tagout standard. It is not to substitute for compliance with the plain terms of the standard. Nothing in this tutorial is intended to diminish or otherwise affect OSHA's authority to enforce the requirements of 29 CFR 1910.147 or of the OSH Act, nor is it intended to create any legally enforceable right or benefit in any person. OSHA.gov.

OSHA Standard Number 1910.147 The 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.

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 more than one source. Isolate- Disconnect all power sources from the robot. Secure- Lock the energy source so that no one can come behind you and flip a switch. Only you can have a key to the lock. If you also have tags, place tags with the lock. Your name should be on the tag and only you are allowed to remove the tag. Validate – Are you sure the robot is isolated? How are you sure? 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 the robot, there is no chance for the robot to inadvertently move due to human error or machine malfunction. Also, power supplies many times contain enough voltage to k ill a person in seconds, if the power source is removed from the robot before maintenance, the chances of injury directly from the power supply are eliminated.

Interlocked Doors Interlocked doors are seen on safety fencing that is typically

installed around the predetermined work envelope of a

robotic system.

The electromechanical switch is normally found on hinges or

on the doors themselves. When the interlock is tripped, the

robot will cease function.

The interlock can be disabled with a key when the robot is

safely disengaged.

Light Curtains Mostly used around robotic systems that need frequent accessibility by the operator, light curtains are extremely reliable for detecting unplanned movement within predetermined spaces near a robot. In a nutshell it’s an invisible wall of light that, when broken, will stop the robot in motion. How it works: - A transmitter located on metal posts around the robotic system

outputs a synchronized pattern of infrared light beams to a receiver on an opposing post, hence, curtain of light.

- The receiver is only programmed to acknowledge these beams preventing an external, unintended light source from interfering.

- When a beam is broken, the work cell is shut down, the robot’s brakes are enabled and the work cell cannot move again until restarted.

http://www.lightcurtain.com/light_curtain-operation.html

Warning Lights

Warning lights are exactly what they say they are. They are lights, usually mounted on the top of the safety

fencing or the PLC and indicate to those working around the robot if the system is operating safely.

The colors of the lights are usually

red, yellow, and green.

Cable Management Cable management is a common issue amongst assembly lines. From atop the

robot to the cables running on the floor, torn, cut, or damaged cables can cause hazardous situations for everyone on the assembly line.

www.hoffmanonline.com www.igus.com

Cable Management Cable management is a common issue amongst assembly lines. From atop the

robot to the cables running on the floor, torn, cut, or damaged cables can cause hazardous situations for everyone on the assembly line.

www.hoffmanonline.com www.igus.com

Some tips on how to make cables last a lifetime:

- Make sure the cables being installed fit the application, many cables are not fit for welding applications and can wear quicker

- Cables on the robot can easily be contained by a sleeve or cable management system. Companies like igus offer retractable and flexible cables for the robot and Hoffman offer cable management throughout the system. - A common reason for replaced cables? Fork Lifts and foot traffic over the cables. Protect your cables from plug to plug.

Remote E-Stops Vary from manufacturer to integrator, make sure the technician installing them teaches you and your operators how to engage them. Found on the teach pendant, around the robotic system and anywhere it is presumed an operator may need to go to operate the robot. Usually are big red buttons placed in obvious places around the robotic system. Not the equivalent of a lockout/tagout (ie: Hazardous Energy Control Procedure). 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 Extractors While what you can see is dangerous, what you can’t see can be just as hazardous to your health. When arc welding, fumes are created that can cause a lot of health problems if inhaled. To protect against these fumes, companies involved with robotic AND manual arc welding should invest in a fume extraction system. Fumes are created during the welding process when some of the welded metal particles are released into the air. Fume extractors can be portable or stationary and some can be installed indoors as well as outdoors.

http://www.asse.org/practicespecialties/articles/weldingfumes.php

http://www.asse.org/practicespecialties/articles/weldingfumes.php

Welding fumes can have long and short-term effects on the:

- Lungs - Brain cells - Nervous system

http://www.asse.org/practicespecialties/articles/weldingfumes.php

Welding fumes can have long and short-term effects on the:

- Lungs - Brain cells - Nervous system

Problems that have been documented include:

- Encephalopathy - Fatigue - Mental confusion - Metal fume fever - Paralysis

Software Most OEMs carry their own branded software now that adds safety mechanisms to their robots. KUKA Robotics, for example, offers KUKA.,SafeOperation software to maximize safety when the robot is in use. The software allows an integrator to configure a safe zone for the robot by defining the cell area, the envelope that the robot 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 robot can move reducing the distance an employee may need to be from the robot. This especially benefits manual loading stations.

www.kuka-robotics.com/usa/en/products/software/hub_technologies/start.htm