Machining of part chamfers

A variety of different effects can be used to modify the edge of the part. The method described here makes it easier to trim the edges of the part.

A variety of different effects can be used to modify the edge of the part. The method described here makes it easier to trim the edges of the part. In an actual machining case, CNC programmers faced inefficiencies in completing the chamfering process described below. The task is to chamfer 0.1 inches around the perimeter of the part and the center cavity. When the customer waits for the parts to be completed, they will often go to the processing site to check the processing progress. The processing progress of the chamfering process is indeed very slow and the customer is not satisfied. Programmers were told to use 3D chamfering to speed up the process. The cutting parameters used in the machining are as follows: speed 7000 rpm, feed 100 inches/minute, step 0.002 inch. The time required to complete the chamfering process was 29 minutes. The biggest problem with this cutting scheme is that the step size is too small, and the step is set in the G code, which cannot be adjusted on the machine. If the cutting parameters are increased as follows: the speed is 10,000 rpm, the feed is 300 inches/minute, the step is 0.006 inches, and the process time can be shortened to 3.8 minutes. 3D method for machining rounded corners. Fillet edges can be machined with rounded corners, but the installation and adjustment of rounded tools is more complicated. Therefore, it is more inclined to use ball end mills to process soft materials such as aluminum and rounded end mills to process steel materials. With this 3D processing method, the computer will do all the considerations with little or no adjustment. The rounded end mill has a shorter cutting length than the cutting edge of the ball end mill, and its cutting force is also smaller. Because it is easy to chamfer and round a part in CAD software, design engineers often chamfer and round the solid model to make the part look better. However, most of them did not realize that the actual machining of rounded corners and chamfering was time consuming, not as simple as chamfering and rounding on a computer.

Hole chamfering with ball end mill and 3D method

The actual machining chamfer is not as easy as it seems on a computer. Since the cutting edge of the chamfering tool has poor cutting performance, if the center cutting is programmed, burrs are generated. This is because the chip evacuation space of the tool tip portion is insufficient, and the theoretical cutting line speed of the tool tip is zero. In addition, the tip is not absolutely sharp. To make the chamfering knife clean and burr-free, the tip needs to be offset from the cutting profile. In the new version of the CAM software, the chamfering knife can be offset to cut out a neat outline. When offsetting the chamfering tool, the depth of the tool is correct. If it is not correct, cut out the uneven chamfer at the inner chamfer. Although this problem can be solved by detailed planning in advance, when the chamfering process is attributed to unimportant feature processing, it is not necessary to consider too much, allowing the computer to solve the related problems. For most chamfers, ball and round end mills can be used and 3D programmed cutting methods can be applied. This way, the computer can do all the considerations without worrying about burrs, offset tools, or uneven chamfering. 

The only consideration is to choose a chamfering cutter so that the tool diameter is less than the minimum diameter of the inner circle to be cut. The disadvantage of this method is that it takes a lot of infeed to complete the entire chamfering cutting, and the processing time is longer. Therefore, it is usually necessary to increase the amount of cutting as much as possible to improve the processing efficiency.