YHP Machining Co., Ltd. · Fenggang, Dongguan
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Quality and inspection

Reports issued as standard: first-article inspection, material certificate, dimensional report — from the facility that made the parts.

Measured at the bench, not assumed
A batch held for first-off inspection
Setup checked before the run

Quality is not a certificate on a wall. It is whether the second batch measures the same as the first, and whether the paperwork you receive matches the parts in the box when an auditor asks.

Our inspection is done by the same team that machines the part, on instruments in the same building. That is not a claim of independence. It is a claim of accountability: there is nobody else to blame, and the person who signs the report can walk to the machine.

How a job is controlled

Four points where a run can go wrong.

1. DFM review before quoting

We read the drawing before we price it, and tell you which feature will be difficult or expensive. That conversation is free and it is cheaper than discovering it in the first article.

2. First-article inspection

The first part of a run is measured in full against the drawing and reported before production continues. If it is out, the run does not start.

3. In-process checks

Critical dimensions are checked through the run at a frequency agreed with the drawing, not only at the beginning and the end.

4. Final inspection and documents

Parts are inspected before packing, and the reports, material certificates and drawing revision used travel with the shipment.

Measurement capability

What each instrument is trusted with.

What is being checkedMeasured onCapability
Hole position and profileCoordinate measuring machine±0.003 mm in a temperature-stable room
Small features and thread formsVision measuring machine2D profile with magnified edge detection
Roundness, cylindricity, runoutRoundness tester0.001 mm resolution on ground faces
Surface finish on seal facesSurface profilometerRa 0.05–10 µm, with the trace recorded
Flatness and parallelismGranite plate and height gaugeDial indicator sweep over the face
Threads and boresGo / no-go and plug gaugesVerification against the named standard
Hardness after treatmentHardness testerConfirmed per batch against the treatment record

Measurement is not the same as capability. We publish what we measure with, and separately we quote the tolerance we can hold repeatably on your feature. Those are two different sentences, and only one of them is worth writing down.

Documents that ship with the parts

  • First-article inspection report
  • Material certificate, traceable to heat number
  • Dimensional report with measured values
  • Hardness or treatment record where applicable
  • Drawing revision used for the run
  • Packing list with quantity and batch

What we will not do

  • Substitute material without written agreement
  • Stamp a report we did not measure
  • Ship a first article that failed without telling you
  • Describe a part as pressure tested without a record
  • Quote a tolerance we cannot hold repeatably
  • Blame the drawing after the parts are made

On the bench

Measured, not assumed.

First-article check
First-article checkThe operator measures before the batch is allowed to continue.
Gear set on the bench
Gear set on the benchTooth-to-tooth and backlash recorded on every set.
Roundness on the tester
Roundness on the tester0.001 mm resolution on ground faces.

Request a quotation

Need a specific inspection plan on the drawing?

Send the drawing and the quality requirement together. We will confirm what we can measure in-house, what needs an outside laboratory, and what that adds to the lead time.