Gate is an opening that allow melt to be injected into the mold. There are many types of gates in injection molding like sprue gate, fan gate, ring gate, standard gate, submarine gate, tab gate etc.Gate type and design depends basically on part packing, part dimension, part appearance etc.
Location of the gate is also an important factor for the strength of a part. In reinforced plastic the orientation of fiber's is the factor that decides the strength of the part and the orientation of fiber's is decided by the location of injection point. If fibres are oriented in the direction of applied stress then part will have maximum strength, if fibres are oriented in a random manner then part will have a medium strength and if fibres are oriented in the direction perpendicular to the applied stress then the part will have lowest strength.