ISO 1502 is an international standard that defines gauging methods for inspecting metric screw threads. It specifies the use of GO and NO-GO thread gauges to verify whether a thread meets the required tolerances according to ISO 965.
This standard is critical for quality control in manufacturing to ensure that internal (nut) and external (bolt) threads fit correctly and function properly.
ISO 1502 is closely related to:
- ISO 68-1 (Metric Thread Profile)
- ISO 261 (Standard Metric Thread Sizes)
- ISO 965 (Metric Thread Tolerances)
Technical Details
ISO 1502 ensures that threaded components meet specified tolerances by using GO and NO-GO gauges.
Types of Thread Gauges in ISO 1502:
✅ GO Gauge (Pass Gauge) – Ensures that the thread is not undersized and fits within tolerance limits.
✅ NO-GO Gauge (Reject Gauge) – Ensures that the thread is not oversized and does not exceed allowable limits.
A properly manufactured thread should fully engage with the GO gauge but should not fully engage with the NO-GO gauge.
Key Concepts in Thread Gauging:
- Internal Threads (Nuts, Tapped Holes) – Checked with plug gauges
- External Threads (Bolts, Screws) – Checked with ring gauges
ISO 1502 Thread Gauge Limits and Sizes
| Nominal Thread Size (M) | GO Gauge Tolerance (mm) | NO-GO Gauge Tolerance (mm) |
|---|---|---|
| M3 × 0.50 | -0.030 | +0.020 |
| M4 × 0.70 | -0.040 | +0.025 |
| M5 × 0.80 | -0.050 | +0.030 |
| M6 × 1.00 | -0.060 | +0.035 |
| M8 × 1.25 | -0.070 | +0.040 |
| M10 × 1.50 | -0.080 | +0.045 |
| M12 × 1.75 | -0.100 | +0.050 |
| M16 × 2.00 | -0.120 | +0.060 |
| M20 × 2.50 | -0.140 | +0.070 |
🔹 Note: The GO gauge should pass freely, while the NO-GO gauge should not fully enter the thread.
Applications of ISO 1502 Thread Gauges
ISO 1502 gauges are used in:
- Manufacturing & Quality Control (Ensuring threads conform to ISO standards.)
- Aerospace & Automotive (Checking precision-engineered fasteners.)
- Machinery & Industrial Equipment (Verifying compatibility of threaded components.)
Thread gauges prevent defects and ensure proper thread engagement.
Related Metric Thread Standards
After reviewing ISO 1502, you may also find these related standards useful:
- ISO 68-1 – Metric Thread Profile (Defines the fundamental shape of metric threads.)
- ISO 261 – Standard Metric Thread Sizes (Covers the full range of standard metric thread sizes.)
- ISO 262 – Preferred Metric Thread Sizes (Specifies the most commonly used metric thread sizes.)
- ISO 724 – Basic Dimensions of Metric Threads (Defines the fundamental dimensions for metric screw threads.)
- ISO 965 – Metric Thread Tolerances (Specifies tolerances for external and internal metric threads.)
These links allow users to easily navigate between related standards.
Important Notice on Standards Validity
This information is for reference purposes only. Users should consult official sources and updated standards to ensure compliance with current regulations.
The validity of standards may change over time, so it is recommended to verify them through recognized engineering and standardization organizations (ISO, DIN, ANSI, ASME, etc.).
Check with relevant standardization bodies in your region to confirm whether a specific standard is still valid and applicable. Regulations and industry requirements may vary based on region and application.