The metric thread plug gauge GO/NO GO is an inspection instrument used to quickly verify the conformity of metric internal threads. Unlike instruments that provide a numerical reading, this type of inspection works on a functional principle: it immediately determines whether the thread is acceptable or not, simplifying production inspection and making checks faster and more immediate.
The operating principle of the GO/NO GO thread plug gauge is simple yet highly effective. The GO side must screw correctly into the internal thread, while the NO GO side must not screw in according to the limit defined for a conforming thread. In this way the inspection quickly verifies whether the thread diameter, pitch and useful dimensions comply with the required limits, without the need for a complete numerical measurement.
This type of metric thread plug gauge is mainly used whenever many components must be inspected quickly, for example after tapping operations or during final production inspection. It is therefore widely used in mechanical workshops, quality control and serial production environments where maintaining inspection speed together with a repeatable inspection criterion is important.
From a technical point of view, metric threads have a 60° triangular profile and can be coarse pitch or fine pitch. For this reason the GO/NO GO thread plug gauge must be selected not only according to the nominal diameter, but also according to the correct thread pitch to be inspected. This correspondence between diameter and pitch is what makes the functional inspection reliable.
The metric thread plug gauges GO/NO GO are available in a wide range of standard executions for inspection of metric internal threads. In addition to standard versions, special thread plug gauges on request can also be manufactured, both with special diameters and pitches and with particular tolerances according to the required application. Executions for left-hand threads and Helicoil applications are also available, covering less standard and more specific dimensional requirements.
From a manufacturing point of view, the thread plug gauge is produced in hardened steel, a characteristic useful for ensuring good wear resistance during repetitive inspections. This aspect is particularly important whenever the instrument is used frequently on production batches, where operational continuity and long-term inspection consistency are fundamental.
Another important point is that the GO/NO GO thread plug gauge is not intended to “measure the thread” in the traditional dimensional sense, but to provide a fast confirmation of functional conformity. In practice, it quickly determines whether an internal thread can be accepted, making it particularly useful whenever fast and simple inspection criteria are required.
This instrument is used on nuts, threaded plates, valve bodies, mechanical components, flanges, machined blocks and in general on all components with metric internal threads requiring fast and repeatable inspection. The possibility of supplying left-hand threads, special tolerances, Helicoil thread gauges and non-standard dimensions further extends its field of application.
Applications
- Fast inspection of metric internal threads
- Functional inspection after tapping operations
- Repetitive inspection on threaded components
- Inspection of nuts, plates, flanges and mechanical parts
- Inspection of coarse and fine pitch metric threads
- Use in workshops, tooling departments and quality control
- Thread plug gauges for Helicoil
- Applications with left-hand or special threads on request
FAQ – Metric thread plug gauge GO/NO GO
What is a metric thread plug gauge GO/NO GO?
It is an inspection instrument used to verify the conformity of metric internal threads using a GO/NO GO system.
How does a GO/NO GO thread plug gauge work?
The GO side must screw correctly into the internal thread, while the NO GO side must not screw in beyond the allowed limit. In this way the inspection quickly verifies whether the thread complies with the required limits.
When are GO/NO GO thread plug gauges used?
They are mainly used in fast production inspections, after tapping operations and whenever threaded components must be checked in a practical and repeatable way.
Why choose a GO/NO GO thread plug gauge instead of a numerical inspection?
Because it provides a faster and more immediate functional conformity inspection of the thread, particularly useful in repetitive production inspections.
What does this instrument inspect in practice?
It verifies the conformity of the internal thread in terms of diameter, pitch and profile according to the functional GO/NO GO principle.
Is it suitable for both coarse pitch and fine pitch threads?
Yes, the metric thread plug gauge is selected according to both the nominal diameter and the thread pitch to be inspected.
What tolerance class is available in the standard series?
The standard series is available in 6H tolerance.
Are special executions available?
Yes, besides standard versions, special executions can also be supplied on request.
Can special diameters and pitches be supplied?
Yes, thread plug gauges with special diameters and pitches can be supplied according to the required application.
Can special tolerances be supplied?
Yes, executions with special tolerances are available whenever the inspection requires characteristics different from standard versions.
Are left-hand thread versions available?
Yes, thread plug gauges for left-hand threads can also be supplied on request.
Are thread plug gauges for Helicoil available?
Yes, thread plug gauges for Helicoil are available on request and are suitable for inspection of threads prepared for threaded inserts.
What material is the GO/NO GO thread plug gauge made from?
It is manufactured in hardened steel, a suitable solution for ensuring good wear resistance during repetitive inspections.
Who is a metric thread plug gauge GO/NO GO intended for?
It is intended for mechanical workshops, tooling departments, inspection and quality control environments requiring fast and reliable inspection of metric internal threads.
What are the most common mistakes when using a thread plug gauge?
The most common mistakes are using the gauge on dirty or burred threads, forcing the NO GO side to screw in and using a gauge with incorrect pitch compared with the thread being inspected.
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