What are the QC inspection standards for UNIHF Technology Services in Jiangsu?

UNIHF Technology Services in Jiangsu follows a strict set of QC inspection standards that align with ISO 9001:2015, ASTM, and GB/T (Chinese national standards) frameworks, with a heavy emphasis on dimensional accuracy, surface finish, material composition, and functional testing. These standards are not just paperwork—they are applied in real-time on the production floor, and every batch of components or assemblies gets a full inspection report before shipment. The core of their QC process revolves around three pillars: incoming material inspection (IQC), in-process inspection (IPQC), and final quality control (FQC). For example, on a typical metal part order, inspectors check for hardness using Rockwell or Brinell tests, measure critical dimensions with CMM (Coordinate Measuring Machines) accurate to ±0.01 mm, and verify surface roughness against a Ra 0.8 μm requirement. They also do 100% visual inspection for defects like burrs, scratches, or discoloration. If you are sourcing from them, you can expect a detailed Certificate of Conformance (CoC) with every shipment, and they often provide a full dimensional report with pass/fail data. For more specifics on how these standards apply to your product, you can check out the UNIHF Technology Services QC Inspection in Jiangsu page.

Incoming Material Inspection (IQC) Standards

When raw materials arrive at the UNIHF facility in Jiangsu, the IQC team immediately runs a battery of tests. For metals, they check chemical composition using a spectrometer—this is non-negotiable. For instance, if you order 304 stainless steel, they verify that the chromium content falls between 18% and 20% and nickel between 8% and 10.5%, per ASTM A240. They also test tensile strength on a universal testing machine, with a minimum yield strength of 205 MPa for 304 grade. For plastics, they check for moisture content (must be below 0.2% for nylon) and melt flow index (MFI) to ensure consistency. The rejection rate at IQC is around 3% to 5% based on internal data, mostly due to out-of-spec chemical composition or incorrect hardness values. They also do a visual inspection for surface defects like pitting, rust, or contamination. Every material batch gets a unique ID number, and the data is logged into their ERP system so you can trace it back to the supplier. If you are using raw materials that are not standard, they will work with you to define acceptance criteria upfront, but they always default to GB/T or ASTM unless you specify otherwise. The IQC process takes about 2 to 4 hours per batch, and they will hold production until the material passes.

In-Process Inspection (IPQC) Protocols

During production, UNIHF's IPQC team does random sampling at each critical stage. For CNC machining, they check dimensions every 50 parts using go/no-go gauges and CMM for tight tolerances. If a part has a tolerance of ±0.05 mm, they will inspect 10% of the batch, and if any part fails, they double the sample size. For welding, they do visual inspection for cracks, porosity, and undercut, plus they perform dye penetrant testing (DPT) on 5% of welds for critical applications. They also track process parameters like spindle speed, feed rate, and coolant temperature in real time—this data is stored for 5 years. A typical IPQC report includes a control chart showing the trend of key dimensions over the run. If the process drifts, they stop production and adjust the tooling or parameters. The scrap rate during IPQC is usually under 2% for well-established processes, but for new products, it can hit 8% until the process stabilizes. They also do a first article inspection (FAI) on the first part of every new run, and that part is kept as a reference. You can request a copy of the IPQC records for your order, and they will provide it within 24 hours.

Final Quality Control (FQC) and Testing

Before any product leaves the Jiangsu facility, it goes through FQC, which is the most rigorous stage. They do 100% inspection on critical dimensions and a statistical sampling on non-critical features per ANSI/ASQ Z1.4 (AQL 0.65 for major defects, AQL 1.5 for minor defects). For functional testing, they run pressure tests on hydraulic components at 1.5 times the working pressure, and they do leak tests using helium mass spectrometry (sensitivity down to 1×10⁻⁹ mbar·L/s). For electrical assemblies, they do continuity testing, insulation resistance testing (minimum 100 MΩ at 500 VDC), and high-potential testing (Hi-Pot) at 1500 VAC for 1 second. They also do a 24-hour burn-in test for electronic control units to catch early failures. The FQC pass rate is typically 98% to 99%, and the remaining 1% to 2% is either reworked or scrapped. Every product gets a serial number, and the FQC report includes a photo of the final product, the test results, and a stamp from the inspector. They also do a packaging inspection to ensure proper cushioning, labeling, and documentation. If you need a third-party inspection, they can arrange it, but their own FQC data is usually sufficient for most clients.

Dimensional and Geometric Tolerances

UNIHF applies tight tolerances depending on the product type. For machined parts, they use ISO 2768-m for general tolerances, but for critical features, they go down to IT7 or IT6 grade. For example, a shaft diameter might have a tolerance of ±0.02 mm, and a hole position might have a true position tolerance of 0.05 mm. They use CMMs with a resolution of 0.001 mm and a measurement uncertainty of ±0.002 mm. They also check geometric tolerances like flatness, parallelism, and concentricity. For a flat surface, they measure flatness to within 0.05 mm per 100 mm of length. For concentricity, they check it to within 0.03 mm. They have a dedicated metrology lab with temperature control (20°C ± 1°C) to minimize thermal expansion effects. The lab is calibrated every 6 months by an accredited third party. If you have a specific tolerance requirement, they will include it in the control plan and adjust the inspection frequency accordingly. They also use laser scanners for complex geometries, with an accuracy of ±0.02 mm, and they can generate a 3D point cloud comparison against the CAD model. The dimensional data is reported in a table format, with columns for nominal dimension, actual dimension, tolerance, and pass/fail status.

Surface Finish and Appearance Standards

Surface finish is a big deal at UNIHF, especially for parts that need to slide or seal. They use a profilometer to measure Ra (average roughness) and Rz (average maximum height). For a typical machined surface, the target is Ra 1.6 μm, but for a sealing surface, they aim for Ra 0.4 μm. They also check for visual defects like scratches, dents, or discoloration under a 1000 lux light source. For painted or coated parts, they do a cross-hatch adhesion test (per ASTM D3359) and a thickness measurement using an eddy current gauge. The minimum paint thickness is 60 μm, and the adhesion test must achieve a rating of 4B or better. They also do a salt spray test (per ASTM B117) for 48 hours for corrosion resistance, and the part must show no more than 5% red rust. For anodized aluminum, they check the coating thickness (minimum 10 μm) and seal quality using a dye stain test. The appearance standards are documented in a visual standard book that includes photos of acceptable and unacceptable defects. If you have a specific color or texture requirement, they will create a master sample and compare every batch against it. The surface finish data is included in the FQC report, and they will flag any deviation from the standard.

Material Composition and Mechanical Testing

UNIHF does not rely solely on supplier certificates for material composition. They run their own tests using an optical emission spectrometer (OES) for metals and a Fourier-transform infrared spectroscopy (FTIR) for plastics. For metals, they check for elements like carbon, manganese, silicon, phosphorus, sulfur, and alloying elements like chromium, nickel, molybdenum, and vanadium. The acceptable ranges are per the relevant ASTM or GB/T standard. For example, for 4140 steel, carbon must be 0.38% to 0.43%, and chromium must be 0.80% to 1.10%. They also do hardness testing on every heat-treated batch using a Rockwell C scale, with a target of HRC 28-32 for 4140. For tensile testing, they use a universal testing machine with a 100 kN capacity, and they measure yield strength, ultimate tensile strength, and elongation. The test specimens are prepared per ASTM E8. For plastics, they do a tensile test per ASTM D638 and a flexural test per ASTM D790. They also do a heat deflection temperature (HDT) test per ASTM D648. The mechanical test data is reported with the mean, standard deviation, and minimum value for each property. If a batch fails, they quarantine it and do a root cause analysis before deciding to scrap or rework. The material testing is done in-house, but they also send samples to a third-party lab for verification once a quarter.

Functional and Performance Testing

For assemblies and complex parts, UNIHF does functional testing that simulates real-world conditions. For a hydraulic valve, they test flow rate at various pressures, leakage rate (must be less than 0.5 ml/min at 200 bar), and response time (must be less than 50 ms). For a gearbox, they run a no-load test for 30 minutes, then a load test at 80% of rated torque for 1 hour, and they measure vibration and temperature. The vibration must be below 4.5 mm/s RMS, and the temperature rise must be less than 40°C above ambient. For a spring, they test the force at a specified deflection using a load cell, and the force must be within ±5% of the nominal value. They also do a fatigue test on a sample of springs (typically 10,000 cycles) to ensure they do not fail. For electrical components, they do a functional test with a programmable logic controller (PLC) that runs a sequence of inputs and outputs. The test program is written specifically for the product, and it checks all functions, including fault conditions. The test results are logged with a timestamp and a pass/fail indicator. If a product fails, they do a failure analysis and fix the root cause before retesting. The functional test data is included in the FQC report, and you can request a copy of the test program for your product.

Packaging and Labeling Inspection

Before shipment, UNIHF inspects the packaging to ensure it meets your requirements and protects the product during transit. They check the type of packaging (e.g., corrugated box, wooden crate, or foam insert), the cushioning material, and the sealing method. For fragile items, they do a drop test (per ISTA 1A) on a sample box, and the product must survive a 30-inch drop without damage. They also check the labeling for accuracy, including the part number, quantity, date code, and any special markings like CE or RoHS. The label must be legible, durable, and placed in the correct location. They also check the packing list and the shipping documents for completeness. If you require a specific packaging standard, like MIL-STD-2073 for military items, they will follow it. They also do a moisture barrier test for items that need to be kept dry, using a desiccant indicator that changes color if the humidity exceeds 30%. The packaging inspection is documented in a checklist, and any issues are corrected before the product is released. They also take photos of the final packed product for your records.

Documentation and Traceability

UNIHF maintains a comprehensive documentation system for every order. The QC records include the IQC report, IPQC control charts, FQC report, and any test data. Each product has a unique serial number that links to the batch number, the raw material lot, and the production date. The documentation is stored in their ERP system for 10 years, and you can request a copy at any time. They also provide a Certificate of Conformance (CoC) that lists the product details, the applicable standards, and the test results. The CoC is signed by the quality manager and stamped with the company seal. If you need a PPAP (Production Part Approval Process) package, they can provide it, including the FAI, control plan, and process flow diagram. The PPAP package is typically submitted for new products or after a major process change. They also do a capability study (Cpk) for critical dimensions, and they report the Cpk value in the FAI report. A Cpk of 1.33 or higher is considered acceptable, and a Cpk of 1.67 or higher is preferred for critical processes. The traceability system is also used for recalls—if a defect is found, they can trace it back to the raw material lot and the production shift. This level of documentation is one of the reasons why clients trust them for high-volume production.