IV. Pre-Start Operating Procedures - Plastics …

1 Lesson 1 NotesPage 4 NOTE: The specific hook-up for every mold is different. For each mold,the connections and their proper sequence must be made andchecked only by qualified Pre-Start Operating ProceduresA. Setting-Up the Mold for Production1. Before the mold is opened for the first time, remove any mold partingline Open the mold and check the mechanical action of the:a. Core pullsb. Side action camsc. Ejection system3. Be sure the nozzle radius and the sprue bushing radius Move the injection unit nozzle against the mold sprue bushing to checkthe seating Injection Mold Protection ProceduresA. Clamp Tonnage Setting1. Do not use excessive clamp Excessive clamp force increases wear on both the machine andthe If the mold clamp area is small, you can indent or hob the platensand even deform the The clamp tonnage setting depends on:a.

2 The projected area of the plastic in the The cavity Typically: Thick parts = 2 tons per square inch Thin-walled parts = 4 tons per square inchPage 5 NotesLesson 1B. Clamp Speed Profile Settings1. The clamp speed profile is another important machine setting forprotecting the mold from unnecessary damage and When you first set the clamp speeds, be conservative. The moldshould close quickly for most of the closing stroke, then slow downbefore is reaches the guide pins and slides, and certainly before themold halves Mold Protection SettingsMold Protection SettingsThe mold protection setting prevents the mold from clamping on anobstruction. At a predetermined closing position the moving platenswitches over from high speed close to slow speed and low pressureclose.

3 In order to detect any obstruction between the mold halves as theycome together, either the closing pressure or the closing time ismonitored during the low pressure close. Exceeding either the allowableclosing pressure or closing time will stop the : Setting the mold protection system is critical. Damaging a moldbecause the mold protection system was not properly set up is acostly mistake and can usually be Assuming the mold halves have no obstructions, the switch over fromlow pressure close to high pressure should be set to occur at a pointwhere the mold halves nearly If the switch over point is too early, the mold is still open and canslam If the switch over point is too late, it could cause false signals tothe mold protection 1 NotesPage 6VI.

4 Injection Mold Set-Up ProceduresA. Ejector Speed1. Hydraulic ejector machine settings:a. Speedb. Pressurec. Distance2. Ejector piston Piston ControlsFor either hydraulic or mechanical ejection systems, do not allow theejector plate to hit the support If the mold has a core pull system, check the system s settings Sequenceb. Speedc. Pressuresd. StrokeB. Dry Cycling1. After all the mechanical mold and machine related functions are set, themachine can be dry During dry cycling, the machine doesn t inject any plastic into the that the clamp and mold operate 7 NotesLesson 1 VII. Protecting The Mold From Damage During ProductionProtecting the MoldMolds look sturdy, but parts of them can be quite fragile.

5 Ejector pins,cores, gates and polished surfaces can be easily damaged. Use carewhen transporting and installing the mold.