An injection-molding tool has at least two separate mold parts forming a set of mold cavities, and a set of runner channels extending between the mold inlet and leading melt flow to the mold cavities. The set of runner channels comprises a number of junctions, each junction dividing a downstream end of a primary runner channel extending upstream from the junction into two or more separate secondary runner channels extending downstream from the junction. A stretch of the downstream end of the primary runner has a cross section area being smaller than the cross section area of the primary runner further upstream from the junction.

An injection molding mold including: a flow path through which a molten resin passes; a main body portion including an introduction portion configured to introduce the molten resin into the flow path and a supply portion configured to supply the molten resin from the flow path to a cavity mold; and a plug unit formed with a plug flow path which is a part of the flow path, the plug unit being attachable to the main body portion, in which a prevention portion configured to prevent a pressure loss from occurring when the molten resin passes through the flow path is formed at a portion of the plug flow path where a moving direction of the molten resin changes.

An injection molding mold including: a flow path through which a molten resin passes; a main body portion including an introduction portion configured to introduce the molten resin into the flow path and a supply portion configured to supply the molten resin from the flow path to a cavity mold; and a plug unit formed with a plug flow path which is a part of the flow path, the plug unit being attachable to the main body portion, in which a prevention portion configured to prevent a pressure loss from occurring when the molten resin passes through the flow path is formed at a portion of the plug flow path where a moving direction of the molten resin changes.

A device for injection-molding and for overmolding objects has an upper element and a lower element, which surround a contiguous volume consisting of a filling space for holding the object and casting material and a sprue for holding casting material. The upper element is movable in relation to the lower element. A piston is arranged within the upper element in an integrated manner and is movable relative to the upper element. The position of the piston can be varied in accordance with a dimension of the object in an axial direction and the piston has a protrusion for changing a volume as filling amount balancing of the casting material within the sprue such that the device is filled with a constant amount of casting material irrespective of the dimension of the object in the axial direction and a volume varying with the dimension of the object in the axial direction.