What is CNC Boring?
What is CNC Boring? CNC machining boring refers to expanding or refining the original holes on the workpiece. The boring characteristics of CNC machining are to correct the eccentricity of the lower hole, obtain the precise hole position, and obtain high-precision roundness, cylindricality and surface finish. Therefore, boring is often used in the final process.
Position error refers to the amount of variation or deviation of the mutual position between the actual surface, axis, or plane of symmetry of the part relative to its ideal position after machining, such as perpendicularity, position, and symmetry.
Compared with cnc machining, boring is a more difficult process. It only needs to adjust a blade (or blade holder) to process micron-sized holes such as H7 and H6.
What Are The Characteristics Of CNC Machining For Boring?
CNC machining is not the same as lathe machining. Because the tool rotates during machining in the machining center, it is impossible to grasp the situation of the tool tip in time to adjust the amount of feed. It is also impossible to change the machining diameter just by adjusting the numerical control buttons like the CNC lathe. This becomes a big obstacle to fully automated machining. It is also because the machining center does not have an automatic diameter adjustment function (except for the U-axis function), which requires that the boring cutter must have a fine-tuning mechanism or automatic compensation function, especially in fine boring, sometimes it must be adjusted at the micron level according to tolerance requirements .
In addition, since the outflow direction of the chips is constantly changing during boring of the machining center, the cutting edge, cooling of the workpiece and the discharge of the chips are much more difficult than when the lathe is machining. Especially when the blind hole rough boring of steel is performed with a vertical machining center, this problem has not been completely solved so far.
2. The Knife
The most common and most troublesome problem in boring is the knife. The main reasons for the occurrence of spring knives on the machining center are as follows
- ① Rigidity of the tool system: including the rigidity of the shank, boring bar, boring head and intermediate connecting parts. Because it is cantilever, the rigidity of the tool is particularly important when machining small holes, deep holes and hard workpieces.
- ② Dynamic balance of the tool system: Relative to the rotation axis of the tool system, if the tool itself has an unbalanced mass, chattering will occur due to the effect of unbalanced centrifugal force during rotation. In particular, the dynamic balance of the tool has a great influence on high-speed machining.
- ③ The rigidity of the workpiece itself or the workpiece: Like some small and thin parts, due to their insufficient rigidity, or due to the shape of the workpiece, they cannot be fully fixed with a reasonable jig.
- ④ The shape of the tip of the blade: The cutting resistance generated by the blade’s rake angle, escape angle, tool tip radius, and chip breaker shape is different.