VÖLKEL Precision Thread Ring Gauges

Always use light fingertip pressure only. A thread ring gauge is a precision measuring instrument and is not designed to compensate for machining errors or to “force itself” onto the thread. If the gauge does not engage smoothly, stop immediately and check the cleanliness, burrs, cutting oil, or misalignment. Excessive torque can damage both the gauge and the workpiece, distort the thread profile, or lead to incorrect pass/fail decisions. If force seems necessary, something is wrong—clean both parts and repeat the test under controlled conditions.

The GO ring checks the maximum material condition of the external thread. It must screw on completely and smoothly over the defined gauging length. If the GO ring cannot pass, the thread is oversized, damaged, or incorrectly machined.

The NO-GO ring checks the minimum material condition. It must not screw on more than the permitted number of turns—typically 1–2 full rotations depending on the standard. If the NO-GO ring goes further, the thread is undersized or out of tolerance.

Only when both conditions are fulfilled—GO fully engages, NO-GO does not—can the external thread be considered dimensionally compliant.

Thread gauges and workpieces are manufactured and calibrated for a reference temperature of 20°C (68°F). Metal expands or contracts with temperature changes. Even small variations can influence the fit between gauge and thread, potentially leading to false results.

For example, a colder workpiece contracts and may give the impression that the thread is too tight, while a warm gauge may expand slightly and fail to engage correctly. For consistent and traceable measurements, allow both the gauge and the component to reach room temperature before testing.

In critical applications, temperature stabilization is considered part of the measurement process.

The ideal recalibration interval depends on usage frequency, environmental conditions, and internal quality requirements. Many companies recalibrate thread gauges annually, but heavy users—such as high-volume production lines—may require shorter intervals.

You should recalibrate immediately if the gauge has been dropped, shows visible wear, or behaves unusually during inspection. Even minor impacts can affect thread geometry.

VÖLKEL offers factory calibration using IAC thread scanners, ensuring traceable measurement results according to DIN, ISO, and ANSI standards. A valid calibration certificate is recommended for all documented quality processes or audits.

If a ring gauge behaves differently than usual—for example, if the GO ring suddenly becomes tight or the NO-GO ring goes farther than expected—immediately stop using it.

First, clean both the gauge and the external thread thoroughly. Remove chips, dust, dried coolant, burrs, and oil residues. Then repeat the test with correct alignment and only fingertip pressure.

If the abnormal behavior persists, the gauge may be worn, damaged, or out of calibration. Continued use could result in incorrect acceptance or rejection of parts. In such cases, remove the gauge from service and have it inspected or recalibrated.

Sudden changes are often early indicators of wear or thread profile deformation—addressing them promptly protects both your gauge and your production quality.