Gardner Business Media

Hot Runner Technology OCT 2017

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F E AT U R E 14 Hot Runner Technology For More Information: MoldTrax Maintenance Solutions / 419-281-0790 / CONTRIBUTOR: Steve Johnson is president of MoldTrax Maintenance Solutions, which provides specialized course work, hands-on bench training, maintenance software, maintenance products, toolroom design and mainte- nance efficiency auditing. FIGURE 4: Use a standard torque setting for the bolt size and a balanced, corner-to- corner pattern to torque manifold bolts if the manufacturer specifications are not available. distance of the nozzles to be off by 0.004 inch over 24 inches in relation to the cavities, resulting in misalignment between the cavities and nozzle seals. This will damage the seals and cause slow, catastrophic plastic leaks. 4 Document all issues throughout mainte- nance, such as poor wiring conditions, wire pinch points, worn electrical connectors, stripped threads and damaged electrical boxes. Take pictures along the way for future reference. 4 Create and use mainte- nance manuals to advance the team's knowledge base about the most appropriate, efficient and safest methods to use when working on a specific manifold system. Although working on hot manifolds is an area of mold maintenance that requires a bit more knowledge, focus, patience and hand skills, these general preparation, disas- sembly and re-assembly guidelines will help structure and simplify a hot runner main- tenance plan. The key is being proactive, creating a data-driven shop environment and encouraging continuous improvement across the toolroom. / HR the bolt sizes in question. Use a balanced, corner-to-corner pattern if a manufacturing torque pattern is not available (see Figure 4). 4 Use an anti-seize product on the bolt threads and under the head to prevent waste in torque force. Technicians often waste as much as 30 percent of torque force to overcome friction. 4 Re-heat nozzles to ease installation if install- ing valve pins. 4 Test manifolds, nozzle heaters and thermo- couples with an ohmmeter or a portable hot runner mold testing system before bolting it onto the back-clamp plate. 4 Recheck heaters and thermocouples for shorts and connectivity issues after the clamp plate is reinstalled and tightened, and then document the readings. 4 Make sure there is no variation in tem- perature between the cavity plate and the nozzle plate when installing a cavity plate to a nozzle plate or working on manifolds in the press while changing or cleaning nozzle tips. For example, a 25-degree difference in temperature could cause the center-line

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