The method of installing parts on CNC lathes is the same as that of general lathes. It is necessary to use existing universal fixtures for clamping as much as possible, and attention should be paid to reducing the number of clamping times, so as to achieve that all the surfaces to be machined on the parts can be processed in one clamping. The part positioning benchmark should be as close as possible to the planning benchmark to reduce the impact of positioning errors on scale accuracy. In order to ensure machining accuracy during the machining process, it is necessary to first position the workpiece in the correct position on the CNC lathe when machining parts, and then clamp it. This process of positioning and clamping is called workpiece clamping. The process equipment used for clamping workpieces is machine tool fixtures.

Six point positioning of workpieces in CNC lathes: The workpiece has six degrees of freedom in space, namely the movement freedom along the x, y, and z right angle coordinate axes and the rolling freedom around these three coordinate axes. Therefore, in order to fully confirm the orientation of the workpiece, it is necessary to eliminate these six degrees of freedom. Usually, six support points (i.e. positioning elements) are used to constrain the key six degrees of freedom, where each support point constrains the corresponding degree of freedom. In the y plane, three support points that are not on the same line constrain the workpiece’s king and three degrees of freedom, which are called the main reference plane; The two support points placed along the length direction on the plane constrain the workpiece to hold two degrees of freedom, and this plane is called the guiding plane; The workpiece of the rolling machine is constrained by a support point on the xoz plane, with one degree of freedom, and this plane is called the stopping plane.

We need to pay attention that before clamping the workpiece on the CNC lathe, the operator needs to first remove impurities such as sand and mud from the workpiece to prevent impurities from getting stuck in the sliding surface of the drag plate, increasing the wear of the guide rail or “biting” the guide rail. When clamping and correcting workpieces with large dimensions, complex shapes, and small clamping areas on a CNC lathe, a wooden bed cover should be placed on the machine bed surface below the workpiece in advance. Together, a pressure plate or a movable top pin should be used to hold the workpiece to prevent it from falling and damaging the machine tool. If the orientation of the workpiece is found to be incorrect or skewed, it is necessary to avoid forceful tapping to prevent affecting the accuracy of the machine spindle. It is necessary to first release the clamping jaws, pressure plates, or top pins slightly, and then carry out step-by-step correction.