Pinpoint gate

Diaphragms or ring gates can be used for molding parts where concentricity is important such as cylindrical parts or parts where weld lines can not be tolerated. Pinpoint gates should not be used unless parts (small) are injected rapidly. Tunnel gating can also be used in such cases. Gate location should be at one of the points listed in Table 6.26. 

Sometimes referred to as pinpoint gate. A small opening between the runner and cavity in an injection or transfer mold. 

FIGURE 1.34 Pinpoint gate without separation from the molded part, s = 0.5 to 2.0 mm... 

Using restraining undercuts helps keeping the runner on the fixed half which leads to tearing off the pinpoint gate. Similar to the tunnel, the runner has to be demolded out of its undercuts using elastic deformation. 

FIGURE 1.39 Three-plate mold with a tear- off pinpoint gate... 

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