MoldMaking Technology

OCT 2018

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34 MoldMaking Technology —— OCTOBER 2018 MAINTENANCE MATTERS with residue or that are installed too tightly extremely time-con- suming. Spring clips are a more eficient method. Control Boxes The design of the control box should enable the connectors to pass through the slots in the covers, ensuring that the con- nectors are part of the wiring harness. Otherwise, completely disconnecting all the wires is required. It is also helpful to hinge covers onto the control box, enabling them to swing open for easy access to the back of the connectors and to the mounting bolts. We recommend mounting control boxes an inch from the plate as opposed to mounting them directly onto the plate. This method provides an air gap that allows vent residue to escape so that the gas does not coat the electrical connections inside the box. Heaters and Thermocouples A full PM requires a technician to remove the nozzles, heaters and thermocouples to clean the manifold plates and the internal air and waterlines. This process can add hours to a PM program if the nozzles are not cleaned regularly and coated with a silicone anti-seize for easy release. Technicians will easily damage nozzle heaters and thermocouples that are stuck if they do not follow careful removal practices. A technician should place the removed heaters and thermocouples on a cart while they are still har- nessed to the connectors. Then the technician should move them to a safe location away from the bench. Some thermocouples are designed to run under the heater the full length of the nozzle, which requires dificult bends stuffed into tight pockets. Designs that are more mainte- nance-friendly route thermocouples outside the nozzle heat- ers, easing removal and installation. Some manifolds have heat- ers that are integrated into the nozzles to yield better tempera- ture control. From a maintenance perspective, this better be true because the trade-off is expensive. The entire nozzle must be replaced if the heater goes bad, and the removal, handling and cleaning is more tedious. Bridges, Manifolds and Nozzles Removing bridges, manifolds and nozzles from the plate assembly is not dificult when the manifold is designed with robust and evenly spaced eyebolt holes in which to lift. This also enables technicians to use an overhead hoist to help break the initial seal instead of relying solely on a pry bar. If using a pry bar, a technician can avoid tool marks and unnecessary dam- age by documenting the process, This special tool provides technicians with a firm grip when they are removing stubborn heaters. The tool will not damage the outer sheath. A roomy, hinged control box with nice "pass-through" slots cut for the connectors.

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