
Testing PROCESSES
Plug Gauge
A Plug Gauge is a precision inspection tool used to verify the internal dimensions of cylindrical components, such as threaded holes or bores. Plug gauges provide a simple and highly accurate method for confirming that a part’s internal diameter or thread depth meets design specifications. They are especially useful for quality inspection of engineered fasteners, ensuring mating parts will fit correctly and function as intended.
How the Inspection is Performed
Calibration – The plug gauge is checked regularly to ensure it will match the nominal diameter or thread standard for the part being tested.
Insertion – The gauge is inserted into the internal feature of the component, such as a threaded hole or bore.
Fit Verification – A proper fit indicates that the part is within tolerance, while a tight or loose fit signals that the part may be out of specification.
Repeatability – Multiple parts can be quickly tested with the same gauge, making it ideal for high-volume production.
Documentation – Inspection results are recorded for traceability and quality assurance.
Why It is Performed
Plug Gauge inspection ensures that internal dimensions, such as bores and threads, meet tight tolerances. This is critical because even small deviations can affect assembly, load transfer, and overall component performance. Using plug gauges allows TSP Manufacturing to verify dimensional accuracy efficiently and reliably, preventing defective parts from entering service.
Confirms internal diameters and thread dimensions
Detects out-of-tolerance components before assembly
Provides fast, repeatable inspection for high-volume production
Ensures consistent quality and fit for mating parts
Application to Engineered Fasteners
Engineered fasteners often engage with other components through threaded holes or precision bores. Accurate internal dimensions are essential for proper load distribution, secure fastening, and safe operation.
By using Plug Gauge inspections, TSP Manufacturing ensures:
Accurate thread and bore dimensions for proper mating and assembly
Conformance to design tolerances for safety-critical applications
Consistent quality across production runs
Reliability in high-performance industries such as aerospace, defense, oil & gas, and nuclear
Standards & Compliance
WN Global performs Plug Gauge inspections in accordance with ASME, ASTM, ISO, and customer-specific standards. Our gauges are routinely calibrated, and inspectors follow rigorous protocols to ensure precise, traceable measurements. Adherence to these standards reinforces WN Global’s credibility and commitment to delivering engineered fasteners that consistently meet the highest quality and performance expectations.
Testing Processes

DOING WHATEVER IT TAKES
Putting Manufacturing Exellence Into Practice
The manufacturing processes, testing capabilities, and quality systems featured throughout WN Global support the production of critical components and engineered fastening solutions across demanding industries. Connect with our team to learn how our manufacturing capabilities can support your project requirements.

