TABLE OF CONTENTS The most familiar example of a multiplate mould tool is probably the three-plate tool. These are used when an over feed gate is necessary, either for multipoint feeding parts or for gating parts to achieve balanced flow. Figure 14.1 shows the basic design requirements for this type of mould tool.
This design is so named because the tool splits into three distinct modules on opening -sections A, B and C. The first opening is usually at the runner position (1). This makes sure the runner is held back onto the snatches ready for subsequent stripping.
The second opening occurs at the main split line to provide clearance for the moulding to be ejected or stripped (2). The third opening (3) occurs when the runner stripper plate is actuated to allow the runner to be ejected from the tool. This type of tool is more expensive to make than a two-plate tool owing to the extra plates and opening movements necessary.
However, there are many three-plate tools that do not split at the runner position first, which can lead to problems with the mouldings sticking back into the cavities as the mould opens. If no control over the opening sequence of the mould opening is provided, the design engineer must be certain this cannot happen.
Hot runner tools are used in preference to three-plate tools wherever this is possible because of the more efficient nature of these systems. However, there...
