Surgical instrument (500), comprising: a handle part (510)； a body part (512) extending distally from the handle part (510) and defining a first longitudinal axis； a movable handle (516) arranged in the handle part (510) and in mechanical cooperation with a drive element (520)； a tool assembly (17) that includes an anvil assembly (20), a cartridge assembly (18) and a contact surface (42), the tool assembly being supported next to a distal end of the body part, a drive beam (802) having a proximal coupling part disposed next to a proximal end thereof and which is configured to engage a part of the actuating element； a closing apparatus (800) arranged next to a distal end of the drive beam (802) that is configured to engage the contact surface (42) of the tool assembly (17), so that at least a partial actuation of the mobile handle (516) moves the closing apparatus (760) distally to a position of engagement with the contact surface (42) to approximate the anvil and the cartridge assembly (18, 20), presenting the closing apparatus (800 ) a horizontal part (806) positioned to engage the contact surface (42) in order to carry out the approximation of the anvil assembly (20) and the cartridge assembly (18)； and characterized in that at least one of the closing apparatus (800) and the contact surface (42) includes a plastic surface (804), at least said horizontal part of the closing apparatus being overmoulded with plastic.Instrumento quirúrgico (500), que comprende: una parte de mango (510)； una parte de cuerpo (512) que se extiende distalmente desde la parte de mango (510) y que define un primer eje longitudinal； un mango móvil (516) dispuesto en la parte de mango (510) y en cooperación mecánica con un elemento de accionamiento (520)； un conjunto de herramienta (17) que incluye un conjunto de yunque (20), un conjunto de cartucho (18) y una superficie de contacto (42), siendo soportado el conjunto de herramienta junto a un extremo distal de la parte de cuerpo, una viga de
