Direct Gate of Plastic Injection Molding

Direct gate of Plastic Injection Molding is the simplest of the gate, which is also the most original.
It is a vertical sprue as shown in the Fig 1.

                    Fig 1 Vertical Sprue

d—the small end diameter of sprue
L—the length of sprue
α—the taper of sprue

Direct gate is a nonrestrictive gate, because of the molten plastic directly into the cavity by direct gate, so the pressure loss is small, filling more easily and can apply all kinds of plastics. The section size of direct gate is usually large and sprue fixed need a long time, so there is plenty of time to fill material, but the large stress produced at the gate.
Direct gate is typically used for large, deep barrel-shaped products. For shallow rectangular products, because of stress and shrinkage, products are prone to warping deformation. At the same time, we need to add fill material process at the gate.
We can set up direct gate at the outer surface of the products as shown in the Fig 2. Should be noted that the big end of the direct gate should not be too large, otherwise can bring difficult to remove gate, also will left a larger mark on the products.

                                                   Fig 2 Outer Surface Direct Gate

We can also set up direct gate at the inner surface of the products as shown in the Fig 3. Some products, in order to ensure the quality of appearance, don't allow the gate directly design on its outer surface, so the gate design must be on the inner surface. This design approach, the product in cover half. When opening the mold, puller hook drive stripper plate, the products will demould from the cover half.

                                               Fig 3 Inner Surface Direct Gate

More information please click here.