Robot payload is one of the most important parameters to consider when selecting an industrial robot. Payload capacity is often one of the first specifications listed by robotic manufacturers and is often used to define a robot. A robot’s payload capacity refers to the amount of mass its wrist can support. While many may think payload only applies to the weight of workpieces handled by the robot, it also applies to the weight of any end of arm tooling (EOAT) and bracketing integrated with the robot wrist. Payload is expressed as a weight unit, with most robot manufacturers using kilograms (kg).
Industrial robots are available in a wide range of payloads from as light as 0.5 kg to as heavy as over 1000 kg. The FANUC LR Mate 200ic is ideal for light part assembly and handling with its payload of only 5 kg. FANUC’s R series is one of their most successful robot lines designed for heavy duty workloads of 80 kg to 270 kg and includes the popular R-2000ib/165F and the R-2000ib/125L. FANUC even has robots capable of handling up to 2300 kg, as they are known for producing some of the strongest robots in the world.
Why is Payload Important?Robot payload is important to consider when selecting a robot as it can have a significant impact on the overall performance of the unit as well as the success of the application. Selecting a robot with too light of a payload can cause the application to fail or even damage to your robot. While selecting a robot with too heavy of a payload can lead to inefficiencies in productivity and cycle times. In addition, unnecessary floorspace can be taken up by the robot as well as cause damage to the workpieces if the payload is too high. Selecting an industrial robot with the proper payload capacity will lead to a fully optimized manufacturing process. Your robot can operate to its full potential allowing for accuracy, increased productivity, and faster cycle times.
EOAT and Robotic PayloadAs mentioned above a robot’s payload does not just refer to the maximum workpiece weight it can handle, but also the weight that can be attached its wrist. Every part that may be attached to the robot wrist needs to be considered including any EOAT as this will affect its payload capacity. For instance, if you have a ABB IRB 2600 with a payload of 20 kg, but a 5 kg gripper is integrated to its wrist, then the maximum part weight it can handle is 15 kg.
Payload capacity is not just limited to material handling applications either, it is also important for others including arc welding, painting, and dispensing to name a few. All of these applications require some form of tooling to be attached to the robot wrist, whether it be a welding torch, paint sprayer, or dispensing nozzle. Since these devices will add additional weight to the robot arm you will need to ensure the robot selected can accommodate this weight for proper functionality. The Motoman HP6 has a payload of 6 kg so it will need an arc welding torch with the same payload or less in order to be able to operate. Fortunately, many end-effectors provide the recommended payload to ease the robot and tooling selection process.