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Mold Selection P4

Previous Page 142 4 Mold Selection gate must be opened to access the mold for servicing. The rear gate is usually either screwed locked, or does not have safety features such as drop bars. Opening the rear gate often stops the operation of the machine completely, even shutting down the hydraulic pumps. Over the years, with these safety features in molding operations, the number of personal injury-accidents has greatly decreased. Referring back the Fig. 4.54, plates (a) and (c) must be locked together solidly even though they are clamped together during injection by the clamping force of the machine. If plastic is injected. | 142 Copyrighted Materials I Copyright 2006 Hanser Publishers Retrieved from www.knovel.com Previous Page 4 Mold Selection gate must be opened to access the mold for servicing. The rear gate is usually either screwed locked or does not have safety features such as drop bars. Opening the rear gate often stops the operation of the machine completely even shutting down the hydraulic pumps. Over the years with these safety features in molding operations the number of personal injury-accidents has greatly decreased. Referring back the Fig. 4.54 plates a and c must be locked together solidly even though they are clamped together during injection by the clamping force of the machine. If plastic is injected inadvertently or deliberately while the clamp is open these plates could see a large separating force the plastic could escape through a gap between these two plates and spray into the open causing injury to bystanders. With any such molds to ensure that these plates are held together securely pairs of large solid screws or clamps are provided on the operator s side of the mold and at the rear of the mold. To pull the plates a and c apart is relatively easy after unlocking them cavity plate a can be latched to the core plate b the clamp is then opened so that plate a moves with the core plate b . As seen above for startup of an insulated runner mold it is necessary to open the mold between plates a and c remove the runner re-close and lock the plates together and restart after closing the safety gates. This presents a serious problem. Since the screws or clamps are on both sides of the mold and this whole operation of unlocking opening cleaning and re-locking must be accomplished within about 15 seconds therefore operators are required on each side of the machine. This can be very unsafe unless other safety measures for the rear gate than the ones mentioned above are provided. There is always a risk of having more than one operator starting up any machine but here they .