Overview

ISO 9157:2002 defines the dimensions for aerospace spline-drive, self‑locking nuts with MJ threads. The self‑locking feature is produced by deforming the nut’s upper portion out‑of‑round. The standard covers nuts intended for specific strength/temperature classifications used in aerospace applications and is intended solely for the compilation of aerospace product standards.

Key classifications covered (tensile strength at ambient temperature / maximum service temperature):

1 100 MPa / 425 °C
1 100 MPa / 650 °C
1 210 MPa / 425 °C
1 210 MPa / 730 °C
1 550 MPa / 235 °C
1 550 MPa / 425 °C
1 550 MPa / 600 °C

Key topics and technical requirements

Dimensional scope: Detailed geometric dimensions are provided (see Figure 1 and Table 1 in the standard) for spline‑drive nuts with thread sizes from MJ4 up to MJ24 (as listed).
Self‑locking method: Locking is achieved by controlled deformation (out‑of‑round) of the nut’s upper section; tool marks are acceptable in this zone.
Units and tolerances: Dimensions and tolerances are expressed in millimetres. Values for form tolerances are given before any surface coatings.
Surface condition: Dimensions apply after any surface coating(s) but before lubrication.
Form and position tolerances: Must conform to ISO 8788 (aerospace metric nut tolerances).
Compatibility: Dimensional values are intended to enable manufacture of nuts that meet procurement specifications ISO 5858 or ISO 8641 depending on classification (temperature limits).
Design freedom: Unspecified shape details are left to the manufacturer within the stated limits.

Practical applications and users

ISO 9157 is used when specifying, designing, producing or inspecting spline‑drive self‑locking nuts for aerospace structures and components. Typical users:

Aerospace designers and structural engineers specifying fasteners for high‑temperature or high‑strength applications
Fastener manufacturers producing MJ‑thread spline‑drive self‑locking nuts
Quality assurance and inspection teams verifying dimensional conformity
Procurement and standards engineers compiling aerospace product standards and procurement documents

Practical benefits include interchangeability, consistent manufacturing criteria, and clear acceptance criteria for nuts used in high‑temperature or high‑load aerospace environments.

Related standards

ISO 5855‑2 - MJ thread limits for bolts and nuts (referenced for thread conformity)
ISO 7403 - Spline drives - metric series (drive dimensions)
ISO 8788 - Aerospace metric nut form and position tolerances
ISO 5858 / ISO 8641 - Procurement specifications for internally locking nuts (classified by max temperature)

Keywords: ISO 9157, spline‑drive nuts, MJ threads, self‑locking nuts, aerospace fasteners, dimensions, high‑temperature nuts, aerospace standard.

Overview

Key classifications covered (tensile strength at ambient temperature / maximum service temperature):

1 100 MPa / 425 °C
1 100 MPa / 650 °C
1 210 MPa / 425 °C
1 210 MPa / 730 °C
1 550 MPa / 235 °C
1 550 MPa / 425 °C
1 550 MPa / 600 °C

Key topics and technical requirements

Dimensional scope: Detailed geometric dimensions are provided (see Figure 1 and Table 1 in the standard) for spline‑drive nuts with thread sizes from MJ4 up to MJ24 (as listed).
Self‑locking method: Locking is achieved by controlled deformation (out‑of‑round) of the nut’s upper section; tool marks are acceptable in this zone.
Units and tolerances: Dimensions and tolerances are expressed in millimetres. Values for form tolerances are given before any surface coatings.
Surface condition: Dimensions apply after any surface coating(s) but before lubrication.
Form and position tolerances: Must conform to ISO 8788 (aerospace metric nut tolerances).
Compatibility: Dimensional values are intended to enable manufacture of nuts that meet procurement specifications ISO 5858 or ISO 8641 depending on classification (temperature limits).
Design freedom: Unspecified shape details are left to the manufacturer within the stated limits.

Practical applications and users

ISO 9157 is used when specifying, designing, producing or inspecting spline‑drive self‑locking nuts for aerospace structures and components. Typical users:

Aerospace designers and structural engineers specifying fasteners for high‑temperature or high‑strength applications
Fastener manufacturers producing MJ‑thread spline‑drive self‑locking nuts
Quality assurance and inspection teams verifying dimensional conformity
Procurement and standards engineers compiling aerospace product standards and procurement documents

Practical benefits include interchangeability, consistent manufacturing criteria, and clear acceptance criteria for nuts used in high‑temperature or high‑load aerospace environments.

Related standards

ISO 5855‑2 - MJ thread limits for bolts and nuts (referenced for thread conformity)
ISO 7403 - Spline drives - metric series (drive dimensions)
ISO 8788 - Aerospace metric nut form and position tolerances
ISO 5858 / ISO 8641 - Procurement specifications for internally locking nuts (classified by max temperature)

Keywords: ISO 9157, spline‑drive nuts, MJ threads, self‑locking nuts, aerospace fasteners, dimensions, high‑temperature nuts, aerospace standard.

ISO 9157:2002 PDF

Technical details

Abstract

Overview

Key topics and technical requirements

Practical applications and users

Related standards

Related standards

Abstract

Overview

Key topics and technical requirements

Practical applications and users

Related standards

Related standards

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