By Jim Montague, Executive Editor
Some of the biggest ideas and history-making events just need a little push to get rolling, take off and change the world. Machine safety's evolution from obstacle to opportunity is one of these.
However, despite lip service about its importance, machine safety still is viewed by management and operators at too many manufacturers as a costly drag on production. As a result, it's often ignored or bypassed, and the tragic injuries and deaths that result are just seen as the cost of doing business. Fortunately, it's become increasingly obvious that a little investment in machine safety now can pay huge long-term dividends in reduced downtime and improved production.
Machine safety is a benefit rather than an expense, and this is shown by the fact that many safety features are becoming standard equipment or low-cost options on today's machinery and equipment. One device, the safety PLC, provides designed-in safety features ready for engineers to incorporate into their applications. For instance, all the equipment in our assembly and components divisions has safety built in ahead of time by using safety PLCs," says Michael Douglas, senior manager and consultant for new technology and standards at General Motors (www.gm.com). Douglas also implemented GM's global health and safety designs and programs, such as its Safety 21 Process, throughout the entire lifecycle of its production systems. "In fact. we've been working with Fanuc for about 18 months to implement its Dual Check Safety software in the robots in our component and assembly divisions. This software defines an individually tailored and password-protected 3D space within which we can lock down and limit a robot's movement, so it can't travel outside of that 3D envelope and possibly injure someone.This feature also usually reduces the number of light curtains required between the operator and robot. The operators use a teaching pendant to lock the robot in its 3D space, which can be viewed on the pendant. This password feature really adds to the confidence level of the local plant's health and safety department."
Consequently, six months ago, GM began installing Dual Check Safety on several dozen of Fanuc's R30iA robots at its new Chevrolet Volt plant near Detroit. Besides protecting operators, Dual Check provides safety without the expense of traditional barriers, such as added safety mats or light curtains.
"The next phase will be to remove the external robot cell fencing by incorporating safety vision systems, such as Pilz' Safety Eye and other safe-motion robot capabilities. These safety features make our robots so safe that operators can walk right up and interface with them," explains Douglas. "This holds possible solutions for many industries' ergonomic part loading issues. For example, back in 2005 at our assembly plant in Spring Hill, Tennessee, we spent more than $100,000 in rework on our hood line resolving ergonomic issues. If technologies like Dual Check Safety had been available in 2005, we would have avoided those rework costs and provided a safe work space for our operators free of ergonomic risks. Technologies that allow for operator interface will also eliminate many hazards for our maintenance workers because they will no longer have to maintain interface equipment that was eliminated by adding these new technologies. Many of the safety features mentioned above can be applied to later-model robots. Users can check with their robot manufacturer for software upgrade details."