Molding fastener stems onto substrate

A method of manufacturing a fastener product includes continuously introducing a sheet of preformed material to a gap defined adjacent a peripheral surface of a rotating mold roll. A lane of resin is also introduced into the gap with the lane overlapping a longitudinal edge of the sheet. The resin is pressed against the sheet in the gap, such that the resin becomes permanently bonded to the sheet, while an array of stems is molded from the resin in the thicker region, the stems extending from a base portion of the resin. Engageable heads are formed on the stems to form fastener elements. The gap is configured with a step in thickness, the step defining a boundary between a relatively thicker gap region and a relatively thinner gap region, the sheet of preformed material being introduced to the gap with its longitudinal edge disposed within the thicker gap region.