Selection Of Machining Positioning Datum For CNC Precision Parts

DALIAN, China - May 9, 2022 - PRLog -- The Principle Of Choosing A Fine Benchmark

(1) The principle of datum coincidence: the surface design data after processing should be as accurate as possible to avoid positioning errors caused by data misalignment.

(2) The principle of unified datum: In order to ensure the relative positional accuracy between the machined surfaces, as many surfaces as possible on the workpiece should be machined using the same set of fine datums as much as possible.

(3) Mutual datum principle of workpiece machining surfaces: The repeated machining method of two machining surfaces can be used as a mutual reference.

(4) Self-based benchmark principle: Some surface finishing processes require small and uniform processing tolerances, often using the processed surface itself as the accuracy benchmark.

The above-mentioned four principles for selecting a precise benchmark are sometimes impossible to satisfy at the same time, and must be decided according to the actual situation.

Principles For Choosing Rough Benchmarks

(1) The rough datum should be used in the first workpiece processing. Whether the rough datum is selected correctly not only affects the processing of the first process, but also has a great influence on the entire process of the workpiece.

(2) The principle of reasonable distribution of machining tolerances: The machining allowance on the surface of the workpiece should be kept uniform, and the important surface should be used as the rough benchmark.

(3) Principle of easy clamping: In order to stabilize the positioning of the workpiece and the clamping is reliable, the selected approximate reference point is required to be as smooth and clean as possible, without lightning strikes, and sufficient supporting area is allowed for forging cuts or other defects.
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