Aerospace Screw Threads

These standards from ISO and SAE cover Standardized Threading for Screws and Bolts requirements sorted by threading. This list covers aerospace screw standards.

ISO 5855-1:1999

Aerospace -- MJ threads -- Part 1: General requirements

This part of ISO 5855 specifies the general requirements for MJ threads used in aerospace construction. It determines the basic triangular profile for this type of thread and gives a system for designating the diameter and pitch combinations. For all diameters 1,6 mm to 300 mm, it offers in the form of tables the basic dimensions and tolerances for a selection of diameter and pitch combinations. It also provides the method of calculation for the dimensions and tolerances for any diameter and pitch combination not given in the tables, including threads with a diameter in excess of 300 mm. For limit dimensions for bolts and nuts of nominal diameter 1,6 mm to 39 mm, see ISO 5855-2. For limit dimensions for fittings for fluid systems, see ISO 5855-3.

ISO 5855-2:1999

Aerospace -- MJ threads -- Part 2: Limit dimensions for bolts and nuts

This part of ISO 5855 specifies limit dimensions of MJ threads for bolts and nuts of nominal diameter 1,6 mm to 39 mm for aerospace construction.

SAE AS 1132K-2021

Bolts, Screws, and Nuts - External Wrenching UNJ Thread, Inch - Design Standard

The scope of this SAE Aerospace Standard (AS) is to define the following dimensional requirements for double hexagon, hexagon head and tee headed bolts, and nuts with AS8879 UNJ inch series threads primarily for use in propulsion systems. Design requirements are based on UNJC threads for sizes 0.1640 and smaller and UNJF threads for sizes 0.1900 and larger.

SAE AS 1338A-2014 (SAE AS1338A-2014)

Aerospace Metric 60┬░ Screw Thread Profile and Tolerance Classes (Stabilized: Sep 2014)

This Aerospace Standard establishes the details of the maximum and minimum thread profile and tolerance classes for the metric 60° screw threads recommended for use in the aerospace industry for metric module bolts and nuts.

SAE AS 3062D-2019

Bolts, Screws, and Studs - Screw Thread Requirements

This standard establishes the rolled thread element tolerances for lead, half-angle, taper, and out-of-roundness for studs used in aerospace construction; it also establishes the requirements for lead threads and runout threads for these studs.

SAE AS 82C-2018

Screw Thread Form, American National, Modified (National Round - NR)

This SAE Aerospace Standard (AS) defines an external thread with a rounded root radius based on a minimum root radius of .108 x Pitch.

SAE AS 8879D-2004 (SAE AS8879D-2004)

Screw Threads - UNJ Profile, Inch Controlled Radius Root with Increased Minor Diameter

This SAE Aerospace Standard (AS) specifies the characteristics of screw threads - UNJ profile inch series, including a mandatory controlled radius as specified in Table 1 at the root of the external thread. The minor diameter of both external and internal threads provides a basic thread height of .5625H to accommodate the external thread maximum root radius. The following detailed design requirements are included: a. Screw threads - UNJ basic profile and design profiles. b. Standard series of diameter-pitch combinations for nominal thread diameters from 0.060 to 6.000 inches. c. Standard thread classes and form tolerances. d. Formulae for thread dimensions and tolerances. e. Method of designating UNJ threads. f. Tables for selected diameter-pitch combinations for close tolerance mechanical thread applications. g. Tables for screw thread - UNJ profile thread limit dimensions. This document specifies the geometric design for each characteristic of screw threads - UNJ profile inch series and the conformance requirements. In addition, the purpose of this standard is to: a. Define the geometric requirements for a selected series of Unified Screw Threads, modified to provide a radius at the external thread root. b. Establish requirements for a continuous radius at the root of the external threads. c. Establish requirements for an increase in the minor diameter of both internal and external threads to accommodate the external thread root radius.

SAE AS 1421A-2010 (SAE AS1421A-2010)

Aerospace Selected Diameter - Pitch Combinations of Metric 60┬░ Screw Threads for Shaft or Bearing Retaining Screw Threads (Cancelled: Nov 2010)

This Aerospace Standard establishes the diameter - pitch combinations of ISO metric 60° screw threads recommended for use in the aerospace industry for metric module shaft or bearing retaining screw threads.

SAE MA 1421A-2018

Aerospace Selected Diameter-Pitch Combinations of Metric 60░ Screw Threads for Shaft or Bearing Retaining Screw Threads

This SAE Aerospace Standard (MA) establishes the diameter-pitch combinations of ISO metric 60° screw threads recommended for use in the aerospace industry for metric module shaft or bearing retaining screw threads.

SAE MA 1508-1996 (SAE MA1508-1996)

Undercuts for Straight Screw Threads - Metric ( Reaffirmed: Oct 2001 May 2006 )

This SAE Aerospace Standard (MA) provides recommended dimensional data for screw thread undercuts for straight 'MJ' metric screw threads in accordance with MA1370. The thread undercut data included in this document are primarily designed to provide a clearance for threading tool runout either where the thread is in a blind hole or where the thread is close to an adjacent shoulder. These thread undercuts are not recommended for bolts, screws, or studs which are required to be necked; e.g., reduced shank contiguous to the thread, to improve their tensile, impact, and cyclic load performance.

SAE MA 1566B-2018

Gaging Practice and Gage Requirements for MJ Metric Screw Threads

This standard covers the gaging practice and gage requirements for aerospace metric screw threads, MJ profile in accordance with MA1370. To establish the gaging system in accordance with ANSI/ASME/B 1.3M for final assessment of dimensional acceptability of the product complete thread (excluding the incomplete lead or runout thread).

SAE MA 1696B-2019

Screw Threads, Metric Buttress - MJB Profile

This standard establishes the basic triangular profile for the MJB thread form, the design profiles, standard pitches, tolerance classes, formulae for tolerances and dimensions, tolerance tables, and a system of designations. Because of the specialized application for buttress threads, no preferred diameter-pitch series have been established for this standard and each application will require use of the thread formulae for dimensions and related tolerances given herein for deriving the thread dimensional requirements.

SAE J 429-2014 (SAE J429-2014)

Mechanical and Material Requirements for Externally Threaded Fasteners

This SAE Standard covers the mechanical and material requirements for inch-series steel bolts, screws, studs, screws for sems , and U-bolts in sizes to 1-1/2 in. inclusive. The term “stud” as referred to herein applies to a cylindrical rod of moderate length threaded on either one or both ends or throughout its entire length. It does not apply to headed, collared, or similar products which are more closely characterized by requirements shown herein for bolts. The mechanical properties included in Table 1 were compiled at an ambient temperature of approximately 20 °C (68 °F). These properties are valid within a temperature range which depends upon the material grade used and thermal and mechanical processing. Other properties such as fatigue behavior, corrosion resistance, impact properties, etc., are beyond the scope of this document and responsibility for ensuring the acceptability of the product for applications where conditions warrant consideration of these other properties shall be borne by the end user.

SAE AIR 1551B-2014 (SAE AIR1551B-2014)

Torque Tightening Metric Screw Threaded Fasteners (Stabilized: Jul 2014)

The purpose of this Aerospace Information Report (AIR) is to provide the aerospace propulsion industry with recommended assembly torque limits for threaded fasteners when a common torque value per fastener size is the objective. (The fasteners are based on the dimensional data in MA1518). It also provides a series of curves that show the effect of the coefficient of friction on the axial load produced in a fastener, when the recommended torques are applied.

SAE J 121-2013 (SAE J121-2013)

Decarburization in Hardened and Tempered Unified Threaded Fasteners (Cancelled: Jan 2013)

This SAE Recommended Practice covers methods for measuring, classifying, and specifying decarburization in the threaded section of hardened and tempered steel bolts, screws, studs, and similar parts. It is not intended to cover products which are specifically carburized to achieve special properties.

SAE J 121M-2013 (SAE J121M-2013)

Decarburization in Hardened and Tempered Metric Threaded Fasteners (Cancelled: Jan 2013)

This SAE Recommended Practice covers methods for measuring, classifying, and specifying decarburization in the threaded section of hardened and tempered steel bolts, screws, studs, and similar parts. It is not intended to cover products which are specifically carburized to achieve special properties.

SAE MA 1520B-2019

Areas for Calculating Stress or Load Values for Metric MJ Externally Threaded Fasteners

Areas for the standard metric series of thread diameter-pitch combinations for aerospace externally threaded fasteners are established for the following conditions: a. Area for ultimate shear stress or load in unthreaded shank. b. Area for ultimate tensile stress or load in thread. c. Area for stress durability test load in thread. d. Area for stress-rupture test load at elevated temperature. e. Area for tension-tension fatigue test load.

SAE MA 4284A-2019

Areas for Calculating Stress or Load Values for Metric MJ Internally Threaded Fasteners

Areas for the standard metric series of threaded diameter-pitch combinations for aerospace internally threaded fasteners are established for the following conditions: a. Area for shear stress or load in fastener thread b. Area for ultimate tensile stress or load in thread

SAE MA 1370-1990 (SAE MA1370-1990)

Screw Threads - MJ Profile, Metric ( Reaffirmed: May 1995 Oct 2001 May 2006 )

To establish a metric module version of the UNJ profile, MIL-S-8879 inch screw thread standard, predominantly used in aerospace inch designs. This standard specifies the characteristics of the MJ profile metric series of screw threads, altered from ISO 68 M Profile, to include a mandatory controlled radius of 0.18042P to 0.15011P at the root of the external thread and with the minor diameter of both external and internal threads increased to provide a basic thread height of 0.5625H in order to accommodate the external thread maximum root radius.