Principles and characteristics of super finishing

          Super finishing is actually a friction polishing process, which is an effective finishing method to reduce surface roughness. It has the advantages of simple equipment, convenient operation, remarkable effect, and good economy. The working principle of super finishing. Ultra-precision machining is a method that uses fine-grained grinding rods (petroleum) to precisely process the surface of the workpiece with a relatively low pressure and cutting speed.

    Super finishing movement. There are three kinds of movement in processing, namely the rotation movement of the workpiece. 1. Axial feed movement of the grinding head 2. High-speed reciprocating vibration of the grinding rod 3. These three kinds of movements are sinusoidal in the trajectory formed by the abrasive particles on the surface of the workpiece.

       The cutting process of super-finishing is different from grinding and grinding. It can only cut off the convex peaks on the surface of the workpiece. When the surface of the workpiece is smoothed, the cutting action can automatically stop. Super finishing can be roughly divided into four stages: the powerful cutting stage, the oilstone abrasive grains are fine, the pressure is small, the oil film between the workpiece and the grinding rod is easy to form, the pressure per unit area is large, so the cutting action is strong; the normal cutting stage, When a few convex peaks are flattened, the pressure on the contact area decreases, and the self-sharpening effect of the cutting abrasive strip is weakened, and it enters the normal cutting stage; in the weak cutting stage, as the cutting area increases, the pressure per unit area is lower, and the cutting The effect is weak, and the fine chips form oxides and are embedded in the gaps of the whetstone, which makes the whetstone produce a smooth surface, which has the effect of friction and polishing to reduce the surface roughness of the workpiece; in the automatic stop phase, the workpiece is ground and the pressure per unit area is extremely low. An oil film is formed between the workpiece and the grinding rod, no snickering, and the snickering effect automatically stops.

       Super finishing features. The super-finishing abrasive grains have complex motion trajectories, which can transition from the cutting process to the polishing process, and the surface roughness Ra value reaches 0.01-0.04μm; the grain size and fineness of the super-finishing abrasive rods can only cut the peaks of the workpiece, so the machining allowance Very small, generally 0.005-0.00025mm; the grinding rod reciprocates at high speed, and the micro-edge of the grinding rod is cut on both sides, so that the grinding debris is easy to clear. Will not form scratches on the surface of the workpiece.