Machining divided head in milling process
Milling operations are performed on a milling machine, in which the cutting tool is held in place on the spindle and spinning at high speed while the workpiece is fed into the cutting tool. One of the common milling operations is the divided head, in which the cutting tool is rotated in a spiral pattern as the workpiece is fed into the cutting tool. This operation is also referred to as helical milling and is used for producing curved surfaces and contours on the workpiece.
In order to successfully perform a divided head milling operation, the spindle must be set up correctly with the cutting tool and the workpiece. The cutting tool should be aligned with the workpiece such that the cutting tool will have a steady cutting speed. The spindle speed should also be appropriate to the machining operations that will be performed.
In addition to these settings, the cutter should be set to the desired feed rate and the depth of cut into the workpiece. The cutting tool must also be securely clamped onto the spindle to prevent it from slipping during the milling operation.
The divided head operation is one of the most commonly used milling operations. It is used for producing a variety of curved surfaces and contours on the workpiece. The divided head operation is usually done on relatively small diameter workpieces, which are usually held in a chuck or held in a collet. The divided head operation can be used to produce a wide variety of part geometries and surface finishes.
The divided head operation is usually accomplished by setting the center of the cutting tool on the centerline of the workpiece. The cutting tool is usually a straight-shank end mill and is secured to the spindle with a collet chuck. The spindle speed and rate of feed should be adjusted to suit the type of cutting tool and the material being machined.
The rate of feed for a divided head milling operation is dependent upon the type of cutting tool being used and the speed of the spindle. Generally, the rate of feed for a divided head milling operation should be set between 0.05 and 0.15 inches per revolution (IPR) depending on the cutting tool and the spindle speed.
The fractional indexing should also be set up correctly before beginning the milling operation. Generally a fractional index number of 40 is used when performing divided head milling operation. The fractional index number is an integer of 1, 2, 4, 8, 16, 32 or 64, which is used to represent the number of indexing steps that make up one complete revolution of the workpiece relative to the cutting tool.
In other words, when a fractional indexing of 40 is used, the workpiece must be rotated a total of forty equally-spaced steps to perform one full revolution relative to the cutting tool. For example, if the spindle speed is set to 1000 RPM, then each indexing step should take about 15 milliseconds, since there are 60,000 milliseconds in one minute.
In order to successfully perform a divided head milling operation, the cutting tool should be rotated at a constant rate of feed, and the rotary table should be setup with the fractional indexing should also be set up correctly before beginning the milling operations. This is typically accomplished by using a mechanical indexing device or a manual crank.
In conclusion, when performing divided head milling operation, the cutting tool should be set up correctly with the spindle and the workpiece, the cutting tool should be securely clamped to the spindle, and the rate of feed and depth of cut should be properly set. Fractional indexing should also be set accurately and a constant rate of feed should be maintained. When these steps are followed, a quality result can be expected.
