Metric thread ring gauge GO/NO GO – SA7796

The metric thread ring gauge GO/NO GO is an inspection instrument used to quickly verify the conformity of metric external threads. Unlike instruments that provide a numerical reading, this type of inspection works on a functional principle: it immediately determines whether the external thread is correct or not, making the inspection simpler, faster and repeatable.

The operating principle of the GO/NO GO thread ring gauge is immediate. The GO ring must screw correctly onto the external thread to be inspected, while the NO GO ring must not give a conforming result. When the inspection provides this outcome, the thread complies with the required limits. This is exactly why GO/NO GO thread ring gauges are widely used in production inspections, where it is important to quickly determine whether a component can be accepted.

From an operational point of view, the thread ring gauge is mainly used to inspect screws, pins, threaded fittings, threaded shafts and in general all components with metric external threads. It is particularly suitable whenever many parts must be checked quickly, using a clear and easily repeatable inspection method directly in production.

Metric threads have a 60° triangular profile and can be coarse pitch or fine pitch. For this reason the metric thread ring gauge GO/NO GO must correspond not only to the nominal diameter, but also to the exact thread pitch to be inspected. This correspondence between diameter, pitch and tolerance is what makes the functional inspection reliable and consistent with the thread under inspection.

The metric thread ring gauges GO/NO GO are available in a wide range of standard executions for inspection of metric external threads. The standard series is produced in 6g tolerance. In addition to standard versions, special thread ring gauges can also be manufactured on request, with special diameters and pitches or with particular tolerances according to the application requirements. Executions for left-hand threads are also available, covering less standard dimensional applications.

From a manufacturing point of view, the thread ring gauge is produced in hardened steel, a useful characteristic for ensuring good wear resistance during repetitive inspections. This aspect becomes particularly important whenever the instrument is frequently used in production and must maintain consistency and reliability over time.

Another important aspect is that thread ring gauges are not intended to numerically measure the thread, but to verify functional conformity in a practical way. In practice, they quickly determine whether the external thread is correct, simplifying the operator’s work and making serial inspections much faster.

For this reason the GO/NO GO thread ring gauge is a widely used solution in mechanical workshops, tooling departments, inspection and quality control environments, especially whenever inspection speed, ease of use and repeatability on multiple parts are important.

Applications

• Fast inspection of metric external threads
• Functional inspection of screws, pins and threaded components
• Repetitive inspection on externally threaded parts
• Inspection of coarse and fine pitch metric threads
• Use in workshops, tooling departments and quality control
• Fast production inspection directly in the workshop
• Inspection of fittings, threaded shafts and turned components
• Applications with left-hand threads, special diameters or special tolerances on request

FAQ – Metric thread ring gauge GO/NO GO

What is a metric thread ring gauge GO/NO GO?
It is an inspection instrument used to verify the conformity of metric external threads using a GO/NO GO system.

What is a GO/NO GO thread ring gauge used for?
It is used to quickly verify whether a metric external thread complies with the required limits, without performing a complete numerical inspection.

How does a metric thread ring gauge work?
The GO ring must screw correctly onto the external thread, while the NO GO ring must not give a conforming result. In this way the inspection quickly verifies whether the thread is correct.

When are thread ring gauges used?
They are mainly used in fast production inspections, final inspections and whenever many threaded components must be checked in a practical and repeatable way.

What does this instrument inspect in practice?
It verifies the functional conformity of the external thread in relation to diameter, pitch and profile.

Is it suitable for both coarse and fine pitch threads?
Yes, the metric thread ring gauge is selected according to both the nominal diameter and the thread pitch to be inspected.

What is the standard tolerance class for these thread ring gauges?
The standard series is available in 6g tolerance.

Can thread ring gauges with special diameters be supplied?
Yes, special thread ring gauges with non-standard diameters can be manufactured on request.

Can special pitches be supplied?
Yes, besides standard versions, executions with special pitches are also available.

Can different tolerances from the standard series be supplied?
Yes, executions with special tolerances can also be manufactured whenever the inspection requires characteristics different from the standard series.

Are left-hand thread versions available?
Yes, thread ring gauges for left-hand threads can also be supplied on request.

What material is the metric thread ring gauge GO/NO GO made from?
It is manufactured in hardened steel, a suitable solution for ensuring good wear resistance during repetitive inspections.

Who is this instrument intended for?
It is intended for mechanical workshops, tooling departments, inspection and quality control environments that need to verify metric external threads in a fast and reliable way.

What are the most common mistakes when using a GO/NO GO thread ring gauge?
The most common mistakes are using the gauge on dirty or burred threads, forcing the NO GO ring onto the thread and using a GO ring with pitch different from the thread being inspected.