278 Industrial Robotics Fundamentals Copyright Goodheart-Willcox Co., Inc. Electromechanical grippers have certain advantages over vacuum grippers. An electromechanical gripper has a longer life and can handle hotter and heavier objects. Also, electromechanical grippers immediately grip a part, while vacuum grippers require time to build up the necessary pressure to grip a part. Electrome- chanical grippers are custom designed for specific applications. Few are available fi as off-the-shelf items. 9.2.2 Tools A robot’s arm can be equipped with various types of tools to perform specificfi tasks. Some of the common tools used on robots are spot welding guns, inert gas arc welders, stud welders, gluing guns, spray guns, drills, milling heads, deburr- ers, polishers, pneumatic screwdrivers, and nut-drivers. The tools used for robotic applications may be categorized as: • Welding tools. • Material application tools. • Machining and assembly tools. Welding Tools Welding tools vary according to the type of welding operation performed. Weld- ing robots may have tool changers that provide fl exibility and improve productiv- fl ity. An automatic tool changer is a device that has more than one end effector and r can change end effectors when needed to execute operations, Figure 9-10. This automated option reduces the downtime required to change an end effector and decreases the risk of operator injury that can occur when a manual change is per- formed. One representative type of welding tool is an arc welding torch attached to a robot arm. For this application, a proximity sensor could be used to aid in positioning the end effector. Spot welding operations can also be performed with robotic systems. Tool changers allow a spot weld device to be attached to a robot arm so multiple func- tions can be performed within a work cell. In addition, laser and gun welding systems may be used with the proper tool changers. Material Application Tools Material application tools are also used in palletizing, packaging, and handling operations. Businesses are very concerned about productivity, so tool changers must be effi to avoid equipment downtime. Rapid tool changing during mate- ficient rial handling automates and improves the process. Machining and Assembly Tools Tooling operations performed for machining and assembly use robots to perform multiple tasks that require several different types of tools. These tasks include operations such as drilling and milling machining processes. Rapid tool changing is critical to productivity for these operations, as is the repeatability of every pro- duction cycle. Robots can change tooling quickly with tool changers that connect the robot arm to the necessary tool in only a few seconds. Sensors can be attached to the robot arm. For example, a proximity sensor can provide feedback about the distance between the end effector and an object. This feedback helps protect equipment from being damaged due to colliding with objects in the work area.