The Positioning Method of Workpieces in Precision Parts Processing

When using a plane as the positioning reference for precision parts processing, the plane of the workpiece and the surface of the positioning part cannot be an absolute ideal plane, and can only be contacted by the three most protruding points. The positions of the three most protruding points are different for each workpiece, and it is possible that the distance between these three points is very close, making the positioning of the workpiece unstable. In order to ensure stable and reliable positioning, three-point positioning is generally used when the workpiece is positioned in a plane. When using the processed plane as the positioning reference, due to the reduced flatness error, in order to improve the rigidity and stability of the positioning, the contact area of the positioning surface can be appropriately increased.

The main positioning components used in fixtures for planar positioning in precision parts processing include support nails, support plates, etc. There are three types of support nails: flat headed, spherical, and toothed. Flat headed support nails are suitable for positioning on machined surfaces, while the other two are suitable for positioning on unprocessed surfaces. The support plate is suitable for positioning on precision machined surfaces or when the positioning reference plane is large.