Abstract: A method and apparatus for making golf ball molds is disclosed. The molds are made by placing a smooth, hemispherical metal cup on top of a dimpled, hemispherical master mold, which is the upper end of a bullet-shaped mounting post. The post is fixed in an upright position to the lower half of a hydraulic press.Above the post is a vertically movable upper press half with a urethane insert. The insert has a smooth hemispherical recess or cavity that is designed in size and shape to blanket the top surface of the cup when the press halves are pushed together.When the press halves are pushed together, the urethane insert covers the cup and pushes against it with extreme force. The insert serves basically as a hydraulic fluid and transforms the linear forces produced by the hydraulic press into a uniform pressure acting equally in all directions against the cup.Due to the tremendous pressure exerted by the press, the insert forces the metal cup to assume the dimpled shape of the underlying master mold.

Abstract: Mold and method of compression molding shell half covers around a core to form golf balls. Opposed dies are pressed together such that some of the material trapped between the approaching dies is forced back into the mold to compensate for shrinkage and the remainder is forced outside of the die cavities where it can be drained off.