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By Tom Lakes,  >SAS< Automation, LLC

With the American Industrial Revolution came the questions, "What is the most cost effective method to produce this product, what operation(s) can we eliminate, what operations can we combine, and how can we eliminate manpower." When Fredick Taylor theorized that by controlling the size, shape, and application of the end effector (shovel) at the end of a human arm, production, cost-effectiveness and profits would improve. Manufacturing is continuing to ask the same questions. The arm and tool may have changed but the questions have not.

End Effectors are today's shovels, and they are on the end of a robotic arm, not a human arm. Yet, the same questions need to be asked: What is the most cost effective method to assemble and to produce this product, what operation(s) can be eliminated, and what operation(s) can be combined to make a more cost- effective operation?

The idea of flexible assembly automation emerged during the 1960's, yet the levels of automation and flexibility have lagged behind the automation of parts manufacturing. Historically, more attention has been paid to manufacturing processes, as it begins with raw materials and changes dramatically, whereas assembly automation was viewed as simply moving parts from one location to another. Justifying manufacturing automation, therefore, has always been easier to do versus assembly automation.

In the past few years the questions mentioned above have been asked, and looking inside the lightweight end effector tool became a priority. The shape, sizes, and weights of parts and the operations desired to be completed by the end-of-arm-tool have increased tremendously.

The ease with which people versus robots can assemble a part is certainly the motivation behind the end effector. The smaller the part the more difficult assembly. The more difficult assembly is by people, the more time needed for assembly. Manual assembly, especially of difficult parts, increases defect rates and decreases quality and cycle times. Manual assembly also requires ongoing training.

Smaller Parts & Shorter Part Life Cycles Look at some of the everyday items you use: cell phones, hand-held tools, office products such as fax machines, copiers and phone systems. These items are progressively getting smaller. The trend for automobiles to reduce weight to improve gas mileage and performance is only going to continue. These smaller products often require a multitude of operations (with each operation requiring an assembler or group of assemblers). Now ask the same perpetual question about manufacturing these small components and clearly managing the automation of these parts becomes a priority to save labor costs, increase productivity and quality.

The trend toward smaller parts has also brought with it decreased part life cycles. Take a look at a cellular phone manufactured two years ago. It's larger, heavier and probably has fewer functions than the 6-month-old phone. Each phone requires a separate set of components. The life cycle of those components is short. To remain competitive, manufactures need the ability to make quick changeovers. To give manufacturers the ability to make quick changeovers, end-of-arm-tools are produced in different ways. The tool itself can be built on a lightweight frame with a quick-change system to allow a quick change from one tool to another, with minimal changeover and adjustment time. Adjustable components also allow the manufacturer to use the same end-of-arm-tool by using the same components in a different configuration. The combination of adjustable tools and quick-change end effectors, combined with the advantages of using robots that are flexible in programming and functions, is saving manufacturers even more. Systems are now available that allow the robot to pick up a tool at a designated area and install the end effector automatically.

The Need for flexibility Not long ago, robots were perceived to be rigid and lack flexibility. Short product life cycle and a need to reduce costs led engineers to look at all aspects of the process. The end effector was the obvious answer to help the robot to become more flexible. The end effector frame can be rigid, but the components need to be flexible. The flexibility is not in the components but in the functions they perform. For example, a component designed and mounted on the end-of-arm-tool to cut or trim a part could not flex during the operation, but the method by which it is attached to the frame would need to be quickly adjustable or flexible to allow the same operation to be performed on a different part. The jaws of grippers or pliers designed and mounted to an end-of-arm-tool would not necessarily need to flex during the assembly, but the advantage of repositioning the gripper at a different angle or position makes the tool more cost-effective.

Think about Fredick Taylor and his shovel experiment. There were two parts to the efficiency equation: the end effector, (shovel) and a human arm. The parts may look different and may be different but there are still at least two components needed: the end effector and the arm. In the case of the robot arm, the robot needs the end effector to perform the assigned task(s) and the end effector needs the robot to perform the assigned task(s). The human arm and shovel performed one task all day long. Bt the robot and end effector are increasingly required to perform multiple tasks, with multiple parts, simultaneously and/or progressively. The robot depends on the ability of the end-of-arm tool to pick, place, manipulate, carry, hold, stack, and any other task(s) the automation cell is asked to do. On the flip side, the end effector depends on the robot to give the correct signal, have sufficient outputs and axis to perform the required task(s). A robot's ability to perform truly comes down to its end effector.

Automotive Parts Assembly Few industries pose as many difficult challenges as the automotive industry. Managing parts automation, from large, bulky, and heavy bumpers and doors to intricate small and delicate covers, requires end effector solutions that are wide reaching.

While many of the functions required of the end-of-arm-tool are typical- grasp the part, feed the part, move the part, align the part after moving it, mount the part into final position, perform final assembly, inspect, shuttle parts(s) to next station - the tools themselves, are not typical. Of course, this is due to the increasingly wide variety of parts that robots are now being asked to handle.

As you look at and study your manufacturing facility, ask "What is the most cost effective method to produce this product, what operation(s) can we eliminate, what operations can we combine, and how can we eliminate manpower? Then think about how to use the team of a robot and flexible end effector as the solution. 

Tom Lakes works for >SAS< Automation LLC in Xenia, Ohio. He can be reached at 937-372-5255. 

Reprinted with permission from RoboticsWorld, June 2001. Published by Douglas Publications,