Questions on Inspection and Calibration

Please click the questions below.

We are planning to check screw thread ring gauge by ourselves. While JIS has many types for checking gauges. Do we need to have all of them?

For Limit Gauge of Metric Screw Thread (JIS B 0251, ISO), 3 kinds of checking gauge is specified for each GO and NO GO gauges as follows,

1.For checking GO Gauge
　GRGF(GO gauge for check GO ring gauge )
　GRNF(NO GO gauge for check GO ring gauge)
　Wear Check Plug

2.For checking NO GO Gauge
　NRGF(GO gauge for check NO GO ring gauge)
　NRNF(NO GO gauge for check NO GO ring gauge)
　Wear Check Plug

Generally, newly produced thread ring gauges are checked using GRGF & GRNF and NRGF & NRNF. While, wear is checked using wear check plug periodically to ensure the wear limit is not exceeded. For routine wear check of thread ring gauge, we recommend you to have wear check plug, which can confirm whether wear limit is exceeded or not.

If you concern about the plating material on screw thread product, which may stick to the thread ring gauge and causing pitch diameter become smaller, we recommend you to have also GO checking plug.

Is there any method to check wear of plug, besides inspection and calibration?

Using a wear check plug is an easy method that operator can judge easily.
Note that there is difference between ISO based JIS and conventional JIS in judging the wear.
In ISO based JIS, wear check plug should not screw in more than 1 turning from both side.
In conventional JIS, wear check plug should not pass through.

Should we request calibration of thread gauge to the JCSS or A2LA authorized calibration institution?

JCSS : Japan Calibration Service system
A2LA : American Association for Laboratory Accreditation

Calibration of thread gauge is not covered items of calibration in JCSS and A2LA authorized representative. Hence, generally, calibration and its certificate issue of such the gauges should be requested to the gauge maker.

We also receive calibration request of standard gauges manufactured by other maker, except for special size of thread ring gauge.

What is calibration certificate and what kind of documents are issued?

A calibration certificate is generally a document that verify the capability and performance of an item of measuring and test equipment by comparison to traceable measurement standards.

Together with calibration certificate, we also issue traceable certificate, traceability system diagram, report on the judgement result, and calibration and inspection certificates of the instruments used for calibration. You are liable for certificate issuing fee.