A molded article 1 is configured such that an insert 2 is made of a steel plate and includes a cylindrical part 2A and an annular part 2B, a plastic 4 is annular in shape so as to be joined to the annular part 2B, inner diameter D1 of the plastic 4 is larger than inner diameter D2 of the annular part 2B so that no burrs at a gate mark E protrude to the inner diameter side of the molded article 1, the injection molding is conducted with a disc gate arranged on an inner peripheral surface F of the plastic 4 at a position separated from a surface of the annular part 2B, and the gate mark E resides on the inner peripheral surface F of the plastic 4 at a position separated from the surface of the annular part 2B.

A molded article 1 is configured such that an insert 2 is made of a steel plate and includes a cylindrical part 2A and an annular part 2B, a plastic 4 is annular in shape so as to be joined to the annular part 2B, inner diameter D1 of the plastic 4 is larger than inner diameter D2 of the annular part 2B so that no burrs at a gate mark E protrude to the inner diameter side of the molded article 1, the injection molding is conducted with a disc gate arranged on an inner peripheral surface F of the plastic 4 at a position separated from a surface of the annular part 2B, and the gate mark E resides on the inner peripheral surface F of the plastic 4 at a position separated from the surface of the annular part 2B.

Providing an injection mold used for producing a molded resin article which is free of a weld line, irrespective of an injection pressure of a molten resin. At least one protrusion is provided in a first region of a ring runner portion defined by an inner circumferential surface of a first communication hole extending toward a cavity and an outer circumferential surface of a pin member disposed coaxially within the first communication hole, such that the protrusion projects from either one of these surfaces and an end face of the protrusion is held in contact with the other of these surfaces. The first region is a half of a circumference of the ring runner portion and is opposite to a circumferential position at which the first communication hole and a second communication hole extending perpendicularly to the first communication hole communicate with each other, with respect to the pin member.

A compression collar is manufactured for use in reinforcing an interference fit between an end of a pipe and a fitting. A precursor form is injection molded using a cold-expansion material. The precursor form has a tubular body with an initially closed axial end and a bore that is initially blind formed in the other axial end. Material is removed from the initially closed axial end of the tubular body of the precursor form to form an opening in the initially closed axial end that connects to the bore thereby forming the compression collar. The opening has an inner periphery with a profile in axial cross section that is different than any profile in axial cross section of an inner periphery of the bore. The collar formed may lack knitlines and may include tabs formed during the removal step which help to position the collar on a pipe.