Overview
ISO 10959:2016 - "Aerospace - MJ threads - Gauging" provides standardized guidance for gauging ISO MJ threads, the thread form used in aerospace fasteners and fittings. The standard specifies gauging principles, gauge types, measurement methods and environmental controls (reference temperature) to ensure thread conformity with the dimensional and form limits given in ISO 5855-1, ISO 5855-2, and ISO 5855-3. Alternative inspection methods are permitted if they are correlated to the specified gauges (see clause 8.2 e)).
Key topics and technical requirements
- Scope and references: Gauging guidance applies to MJ thread products for aerospace applications and relies on normative references including ISO 1, ISO 1502, and ISO 5408.
- Types of gauges: Defines applicable gauges for external and internal threads:
- External: GO screw ring gauges, virtual pitch diameter indicating gauges, simple pitch diameter indicating gauges, major/minor diameter gauges, and optical comparator checks.
- Internal: GO screw plug gauges, NOT GO plug gauges, plain minor diameter plugs, GO full-form plug gauges, and indicating gauges.
- Virtual vs simple pitch diameter:
- Virtual pitch diameter indicating gauges measure the maximum-material virtual pitch diameter on segments or rolls and account for form variations (pitch, helix, flank, roundness, taper).
- Simple pitch diameter gauges (cone/vee or best-wire contacts) check that pitch diameter is above the minimum limit and are correlated with virtual-diameter measurements.
- GO / NOT GO principles: Use GO gauges to confirm ease of assembly and maximum-material limits; NOT GO gauges to verify minimum-limits are not exceeded.
- Controlled root radius: The standard requires a modified GO full-form plug gauge for internal threads with a controlled root radius matching the maximum external thread root radius specified in ISO 5855 series.
- Reference temperature: Gauging should be performed at 20 °C (ISO 1). Permitted tolerances: ±2 °C for sizes MJ24 and smaller; ±1 °C for larger sizes, unless product and gauge have identical thermal expansion.
- Use of optical comparator and setting plugs: Optical comparators verify root radius and minor diameter; setting plugs are required for adjustable GO gauges and indicating gauges.
Practical applications and users
This standard is essential for:
- Aerospace manufacturers and assembly shops producing MJ-thread bolts, nuts, and fittings
- Fastener and gauge manufacturers designing GO/NOT GO and indicating thread gauges
- Quality and inspection engineers, metrology labs, and suppliers needing traceable thread verification
- Design and procurement teams specifying thread acceptance criteria for aerospace components
ISO 10959:2016 ensures consistent, repeatable gauging practices for critical aerospace threads, reducing assembly failures and improving interchangeability.
Related standards
- ISO 5855-1 / -2 / -3 - MJ threads general requirements and limit dimensions
- ISO 1502 - General-purpose metric screw threads - Gauges and gauging
- ISO 5408 - Screw threads vocabulary
- ISO 1 - Standard reference temperature for geometrical product specification and verification
Keywords: ISO 10959:2016, MJ threads gauging, aerospace thread gauges, virtual pitch diameter, GO gauge, NOT GO gauge, ISO 5855, thread inspection, reference temperature.