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Issue link: https://mms.epubxp.com/i/155490
feature pallet moves from or returns to any pallet receiver in this sub cell. Smaller pallets such as System 3R Macro or Magnum can be mounted on the larger Dynafix pallets for extended machining cycles. RFID chips installed on all pallets enable the robot to make positive identification when retrieving or storing a pallet. A VitAl Bridge Devising a system so custom work could take advantage of palletization, yet be compatible with flexible, manual operation, was a challenge for the MegaCell design team, Mr. Graham says. The solution was adopting special magnetic chucks developed by The Hermann Schmidt Co. (South Windsor, Connecticut) that interface with the 3R pallet receivers. These magnetic chucks are equipped with precision-ground, precisely located side rails that establish repeatable workpiece orientation. The magnetic chucks ser ve as the bridge between automated, untended operation of the sub cell and manual operation for custom work, Mr. Graham explains. "The goal is always to have enough work in the regular pallets to keep the machines in the cell running around the clock in the automated mode. In the meantime, custom work can be fixtured at the bench on the magnetic chucks, and then either entered for robotic delivery or loaded by hand after the machine is taken offline," he says. The magnetic chucks enable a variety of clamping units to be mounted singly or in multiples. These clamping units, all affixed to the System 3R Dynafix palletizing system, include the smaller Mini and Magnum pallets or other types of convenient workholding devices. When set up, a magnetic chuck can be entered at the sub cell's load/unload station, sent to the CMM to verify all workpiece positions, then delivered to the appropriate machining center or EDM, where an operator is expecting it. Any other Dynafix-mounted workholding unit can be handled in the same way. The magnetic chucks are not used exclusively for custom work, however. Workpieces such as pins or bushings that can't be clamped in palletable System 3R fixtures can be held in V-blocks or vises for mounting on the magnetic chucks. Thus, the magnetic chucks enhance both auto- Magnetic chucks attached to standard pallets enable many types of clamping devices to hold parts for custom work. The chucks shown here are in storage on shelves of the carrousel. mated and manual operations on the sub cell. Mr. Graham stresses that, regardless of the mode of operation, a key component in the sub cell's effectiveness is consistent reliance on the master gage balls assigned to each workstation. These master gage balls are used to locate any item to a common, known reference point. Coordinate positioning (X, Y and Z) and machine offsets are always established in relation to the master gage ball, whether the work is mounted on the magnet, a fixture on the magnet, or a Dynafixmounted Macro or Magnum pallet. Customized Cell/mAChine Control Some of the most important provisions for accommodating custom work are not visible in a tour of mmsonline.com September 2013 MMS 81