A method of manufacturing a closure member for a surgical instrument, the method comprising the following steps: providing a closure member including an upper flange portion, a lower flange portion and a vertical beam portion interconnecting the upper flange portion and the lower flange portion, the upper and lower flange portions having an internal surface and an external surface； drilling a hole through at least one of the upper and lower flange portions, the hole extending from the external surface to the internal surface of the at least one upper and lower flange portion； and injecting a material having a low coefficient of friction through the hole using an injection molding process to cover at least a portion of the internal surface of the at least one upper and lower flange portion.
