The "Teli" series shearing machine produced by our factory, the back retaining plate is one of the key parts (Fig. 1), the straightness requirement is 0.04mm, and the total length is 1500~200mm. In the past, the clamp was clamped and the gantry was processed in one piece. Straightness does not meet design requirements and is inefficient. For this we designed a milling half-face clamp. The clamp structure is as shown in FIG. 2, and the pressure plate 3 and the intermediate pressure plate 6 pass the nut 1 to clamp the two workpieces on the left side.