Two-set process of creating accurate holes
In machining when a hole is required by the application, it is generated through drilling. But sometimes, when drilling from a solid, a pilot drill is used to mark where the drill has to start. As the drill advances through the workpiece, it can encounter certain vagaries in the material or inconsistencies like inclusions and hard spots. Should this happen, the drill tends to deflect or wander from its course slightly. In some applications, the drill can wander to about 0.008 to 0.015 of an inch. In order to straighten the hole, a boring bar is set to the exact diameter initially and then gradually brought to size in incremental phases. After employing the boring mills, it is expected that the size of the hole will be according to specifications with tight surface finish. In some cases, a reaming tool can be used to further smooth the hole and bring its size to the required diameter.
How interpolation can reduce the number of steps in creating a hole
There are machine shops that face demanding production to meet shipping schedules. They would benefit if the steps required at creating a hole is minimized particularly if drilling has a significant impact on throughput and productivity. In order to simplify the process, interpolation on the face milling cutter will eliminate the pilot drilling sequence or the boring sequence. If differently sized holes can be bored using one cutter, a lot of efforts and time will be saved. Interpolation is actually done through CNC technology so that the operator does not have to think of how big or how deep to make an accurate circle. Circular interpolation will involve the simultaneous motion of two of the three axes on a standards three-axes machining center. The cutting tool will be fed to a programmed depth of cut and interpolation will be performed by combination moves in the Y and X axes.
If helical interpolation will be used, as the X and Y axes interpolate a circle, the Z axis will be fed down in a spiral motion until the programmed depth is reached. When the circular and helical interpolations are used on the face milling cutters, holes that are as close to boring bar quality in roundness, size and finish will be produced. Through interpolations, face mills will be capable of double-duty for linear milling of planar surfaces and helical milling of holes. Face milling is the most common among milling operations because it can be used with a wide range of tools.