Insert-molded ball joint

An insert-molded ball joint, comprising:

• a ball stud made of metal, the ball stud having a spherical head;
• a ball seat into which the spherical head of the ball stud is rotatably inserted, the ball seat being made of synthetic resin;
• a housing formed by injection molding using synthetic resin, the housing covering the ball seat and a portion of the spherical head of the ball stud that is exposed from the ball seat,
• wherein an upper end of the ball seat is disposed higher than an imaginary horizontal plane passing through a center of the spherical head of the ball stud,
• the housing comprises a head support extending from the upper end of the ball seat and contacting an upper portion of the spherical head of the ball stud to prevent the ball stud from being removed from the housing,
• a ball seat grease groove is formed in an inner surface of the ball seat, the ball seat grease groove being sealed with the spherical head of the ball stud, and
• a plurality of housing grease grooves are formed in the head support of the ball stud in a vertical direction, the plurality of housing grease grooves being in contact with the upper end of the ball seat.