06 · Core Capability
Assembly &quality testing
The final step in our vertically integrated manufacturing process. Every component — die-cast, stamped, machined, molded, and surface-treated — comes together on our assembly lines. Our in-house QC laboratory performs 8 categories of testing to ensure every product meets specification before shipment.
Assembly Process
From components to finished product
Component Staging
All die-cast bodies, stamped springs, machined cams, injection-molded handles, and surface-treated parts are staged at the assembly line.
Sub-Assembly
Lock cores, cam mechanisms, and spring assemblies are built up in stages with torque-controlled fastening.
Final Assembly
Complete lock or latch assembled with keys, mounting hardware, and any electronic components (for smart locks).
In-Process Inspection
Visual and dimensional checks at each assembly station. Functional testing of every lock mechanism before proceeding.
Final QC & Packing
Finished products undergo final inspection per AQL sampling plan. Custom packaging, labeling, and palletizing for FOB Ningbo shipment.
Quality Testing Laboratory
8 testing capabilities
Coating Thickness Testing
Non-destructive measurement of plating and coating thickness using X-ray fluorescence (XRF). Verifies zinc, nickel, chrome, and powder coat thickness to specification.
Standard: ASTM B568
Metal Composition Analysis
Spectrometric analysis of raw material and finished parts to verify alloy composition. Ensures incoming zinc and aluminum alloys meet Zamak 3/5 or ADC12/A380 specifications.
Standard: ASTM E1251
Hardness Testing
Rockwell and Vickers hardness measurement for material verification and heat treatment validation. Covers HRC, HRB, and HV scales.
Standard: ASTM E18 / E92
Salt Spray Testing
Accelerated corrosion testing in controlled salt fog environment. Our GY-60 chamber tests surface treatments to 500+ hours per ASTM B117, verifying long-term durability in harsh environments.
Standard: ASTM B117
Torque Testing
Measurement of lock mechanism rotational force, latch engagement strength, and fastener torque. Ensures consistent operational feel and structural integrity.
Standard: In-house standard
2D Optical Measurement
Non-contact dimensional inspection using high-resolution imaging systems. Measures profiles, holes, angles, and distances with micron-level accuracy on flat and semi-flat parts.
Standard: ISO 10360
Spring Tension Testing
Force measurement for springs, clips, and elastic components. Validates spring constant, free length, and maximum load for lock springs and retaining elements.
Standard: In-house standard
High-Temperature Aging
Accelerated lifecycle testing at elevated temperatures (typically 70-150C). Simulates years of real-world use to verify material stability, coating adhesion, and mechanical performance over time.
Standard: In-house standard
QC Equipment
Laboratory instruments
| Instrument | Model |
|---|---|
| Salt Spray Test Chamber | GY-60 |
| Rockwell Hardness Tester | HR-150A |
| Torque & Spring Tester | -- |
| Gas Spring Pressure Tester | WST-YS500 |
| Coating Thickness Gauge (XRF) | -- |
| High-Temperature Aging Chamber | -- |
| Rain Test Chamber (IP Rating) | -- |
Quality Philosophy
Built into every step
Quality at Hengchieh is not an inspection gate at the end of the line — it is integrated into every manufacturing step. Our IATF 16949 and ISO 9001 quality management systems require documented control plans, statistical process control (SPC), and corrective action procedures at each production stage.
Every incoming material batch is tested for composition and hardness. Die-cast parts are inspected for porosity and dimensional accuracy. Surface treatments are verified for thickness and adhesion. And every assembled lock mechanism is functionally tested — 100%, not sampled — before packaging.
This approach ensures that defects are caught at the earliest possible stage, reducing waste and guaranteeing that the products reaching our customers consistently meet specification.
Get Started
Discuss your quality requirements
Tell us your testing standards and inspection requirements. We tailor our QC process to match your specifications.