27 www.drivesncontrols.com October 2023 ROBOTS n 3. Evaluate the applications Score each application based on the following considerations: Is it a precision task? Does it involve uncomfortable motions? Does it result in high rejection rates? Does it involve heavy loads? Is a constant human presence needed? Does the human operator add any value? What speed does the task need to be performed at? From experience, we know that welding, pick-and-place and machineloading are often ideal candidates for cobot applications. 4. Consider safety concerns Assess the safety of your chosen application: does the cobot need to be guarded, unguarded or part-guarded? For example, depending on the application and risk assessment, Fanuc cobots can work safely alongside humans unguarded at speeds of up to 250mm per second, so speed is a good indicator as to whether a cobot is the right automation technology for the task. That said, it is not always clearcut. Part-guarding or other safety devices, can be employed to enable cobots to work alongside humans at higher speeds. However, if the application requires full guarding, making it less flexible and adding to the cost, a cobot may not be the right answer. 5. Protect your investment The International Federation of Robotics considers the average lifespan of a robot to be 12 years. Studies suggest this is a conservative estimate. To protect your investment, it is vital that you buy from a brand that is still going to be around in 13, 14, 15 or more years’ time and will support your cobot throughout its lifespan. Ask potential suppliers for the predicted life of their cobots, how long they will be supported for, how futureproof they are is in terms of software, and what warranty they offer. For example, Fanuc’s CRX collaborative robots come with eight-year zero-maintenance guarantees. 6. Calculate payload and reach The biggest mistake companies make with regard to payload is to go too low. Don’t assume that if a cobot has a payload of 5kg it can lift an item weighing 5kg. To work out your payload requirement, calculate the total load on the end of the arm (part + gripper + fingers etc) while taking into account offset payload and inertia. When calculating reach, bear in mind that working at full reach limits the cobot’s movement in the robot wrist, so build in additional margin. To help manufacturers choose the right payload and reach for their needs, our CRX range comes in five sizes, with payloads from 5kg and reaches from 994mm, up to payloads of 25kg and reaches of 1,889mm. 7. Select sensors and ancillary equipment If your application requires 2D or 3D vision, consider where you want to mount the camera (remotely or on the cobot). If the cobot will always pick from the same area, a remote camera is best mounted above the picking area, whereas a camera mounted on the cobot will give you more flexibility. Force sensors (which give the cobot a “feel” function) can be internal or external. The use of vision will not only offer more flexibility but cut the costs of fixturing required to position parts. 8. Evaluate your environment If you are planning to use the cobot in a food production environment, you will need to think about its IP rating and washdown protection. If the cobot is intended for use in a dusty or dirty environment, or is likely to come into contact with machine coolants, you will also need a high protection rating (IP67 or above). When enquiring about IP ratings, make sure that they apply to the entire system, including the controls, not just the arm. For example, Fanuc’s CRX cobots are IP67 rated with food versions covered in a white epoxy coating with food-grade grease, making them safe to use in food production areas. 9. Consider connectivity Does the cobot need to communicate with other equipment, such as CNC machines, part-feeding systems, grippers or vision systems? If so, specifying a cobot that supports the same communications protocols as peripheral equipment will cut costs and integration time. If possible, keep it simple by using standard I/O. However, some applications require some form of fieldbus because it allows larger amounts of data to be communicated to peripheral equipment. 10. Plan for the future Finally, think about how flexible the cobot needs to be to meet your future needs. Will it be able to accommodate new applications and growth? Does it have software that can be updated and supported? Also bear in mind that if you buy from a company that manufactures only cobots, and in future you need an industrial robot, there will be a new learning curve. There is a lot at stake when buying a cobot for the first time. As well as driving productivity and health & safety performance improvements, a positive experience will pave the way for further automation of more profitable applications and inspire employees as you continue on your automation journey. n Cobots’ can be used with end-effectors from third-party suppliers such as this gripper from OnRobot
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