Curved surface parts and curved surface molds are very suitable types of workpieces for CNC processing. In the industrial field, curved surface parts are also widely used, such as turbine blades, ship propellers, various cylindrical and conical industrial products, etc. When processing curved surfaces, milling is generally used. So, what should be noted in CNC curved surface processing? What should the complete surface processing process look like?

The processing of curved surface parts also follows the CNC processing rules, namely rough processing (roughing) - semi-finishing - finishing - detail processing. Free-form curved surfaces cannot be clearly expressed by geometric construction and mechanical drawing, making it a primary problem to be solved during the CNC curved surface processing roughing stage.

CNC Curved Surface Processing: Roughing

When initially processing the blank of a curved surface part, to improve milling efficiency, a vertical milling cutter is used to mill in layers along the contour surfaces according to the allowance given by the surface to be processed. After rough milling, the shape of the curved surface will appear tiered, with the step height depending on the rough milling accuracy. During rough processing, since the processing allowance and cutting amount are relatively large, a large amount of cutting heat is generated during the cutting process, which can quickly wear out the tool. At this stage, cutting fluid should be used to lower the temperature of the cutting region, serving lubricating and cooling functions.

CNC Curved Surface Processing: Semi-Roughing

Semi-roughing is indispensable as it is an important stage between roughing and finishing, aiming to remove the excess material left from the rough milling steps. Semi-finishing milling should be performed using a ball-end mill, and its spacing and step distance should be larger than that of the finishing milling. It is important to note that semi-finishing milling should leave a processing allowance of about 0.5 millimeters for the subsequent finishing process. After this procedure, the surface shape is already close to the theoretical curved surface.

CNC Curved Surface Processing: Finishing

Finishing is the process of finally producing the theoretical curved surface. The preferred tool for finishing is the ball-end mill, which generally uses the line-by-line cutting method. In programming, it is important to select the turnaround point and determine the feed speed. For parts with good openness, the turnaround point should be chosen outside the curve surface, meaning the surface should be appropriately extended outward during programming.