Process
This process uses multiple diamond-plated, barrel-shaped tools to finish a bore. The tool has a single layer of diamonds bonded to the tool, with about half of each diamond exposed. These special tools are made to a specific diameter and are only meant to open up the hole to that size.
The tools are usually mounted in a dedicated bore finishing machine, however they can also be mounted in a milling machine. In either case the tool, workpiece, or both are rotated and the tool is plunged into the bore and removed. The part is then transferred to the next station or a larger tool is mounted and a larger bore machined, and the process repeated until the desired bore geometry is reached. The number of tools required to achieve the desired bore size is dependent on the workpiece material, the amount of stock to be removed and geometrical requirements, with four to six tool pieces being common. Each tool is progressively larger than the last, but in diminishing increments; as the stock removal is reduced, so is the tool's diamond grit size.
The process is similar to honing, in that the tool follows the existing center line of the bore. To make sure the tool follows the existing center line, the tool, workpiece, or both are allowed to float. Usually just the workpiece is floated, but both pieces may be floated to get the tightest tolerances, however this greatly increases complexity. For workpieces that are larger than approximately 1 kg (2.2 lb) it may be more feasible to float the tool. The process can achieve a size tolerance of 0.001 mm (3.9×10−5 in) and a geometry tolerance of 0.0003 mm (1.2×10−5 in) in production.
Read more about this topic: Single-pass Bore Finishing
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