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How hydraulic pump parts are machined and finished
The production route from bar stock through turning, heat treatment, grinding, lapping, inspection and bench testing.
The sequence matters as much as the operations. Parts are turned close to size, then heat treated, then finish ground, because heat treatment moves material and any dimension held before it will not survive it. Shops that grind before hardening produce parts that measure correctly on the bench and fail in the pump.
Lapping is the step that separates a working part from an approximate one. Valve plates, swash plates and cylinder block faces are lapped flat to a few light bands, because the oil film that separates them is thinner than the flatness error of a merely ground surface. This is done in matched pairs where the parts run against each other.
Inspection is dimensional and functional. Dimensions are checked against the original drawing, then assembled rotary groups are bench run to confirm flow and pressure before packing. A part that measures correctly but leaks at pressure has still failed.
Specifications
| Route | Turn → heat treat → grind → lap → inspect → bench test |
|---|---|
| Why that order | Heat treatment moves material; finishing must follow it |
| Final check | Flow and pressure on the bench, not dimensions alone |
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