MoldMaking Technology

OCT 2018

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32 MoldMaking Technology —— OCTOBER 2018 MAINTENANCE MATTERS Manifolds: To PM or Not to PM, Part 3 By Steve Johnson The August issue's article on mani- folds and preventive maintenance (PM) explained the impact of environmental factors on manifold performance. This piece focuses on the impact of ive non- maintenance-friendly manifold design fea- tures that our repair technician students shared. They claim that these features complicate manifold PMs to such a level that the technicians would rather wait until the manifold breaks to repair it. Valve Pins and Piston Components Technicians usually remove the valve pins and piston components irst so that they can gain access to the manifold. Some systems have as many as •• components per position, comprising the piston-cup assembly (not including the seals), which technicians must carefully remove and place in a holder or tray so as not to dam- age or mix up the position of the fragile tips. A huge time-saver is a system design that only requires the technician to remove the valve pin to split the mold, as the piston housing com- ponents can remain in the plate. For a •‚-cavity tool, this can save four to eight hours and several dollars in O-rings or seals (and much more if the components are particularly dificult to reinstall). Wiring Technicians often com- plain about systems that require a complete teardown to replace a nozzle heater or thermocouple. This process results in lower cavitation, as molders cannot afford to have a mold down to regain one or two cavities. Fortunately, most manifold designs today front- load these components, which enables technicians to replace them in the press. Often, disconnecting the wires at the control box and pull- ing them through the access holes to route through the plate is the most labor-intensive part of the PM process on molds with eight cavities or more. To avoid this, we recommend mill- ing through the plates whenever possible, which allows the technician to wire-tie the wires together (still screwed into the connector strips), forming a unit or harness for removal and installation. We have seen this method knock off another four to eight hours and reduce the chance of damage to the con- nector screw or a mix up with the heater and thermocouple. The use of clips to hold the wires that lead to the control box in wire channels that are "too small" is another design pet peeve of many technicians. The clips are individually screwed in, which makes the process of removing screws that are illed Here, a technician uses specifically weighted slide hammers to control the force he is applying as he removes valve pins. This technique reduces the risk of damage. Images courtesy of MoldTrax. This manifold has holes after slotting that yield faster and safer removal and installation of the electrical wiring. Use a cover over the slots, if necessary. A huge time-saver is a system design that only requires the technician to remove the valve pin to split the mold, as the piston housing components can remain in the plate.

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