Overview
ISO 12258:1998 is an international standard developed by the International Organization for Standardization (ISO) that specifies the dimensions and configurations of aerospace bolts featuring a reduced bihexagonal head. These bolts have either a normal or pitch diameter shank and long-length MJ threads. They are made from metallic materials and can be either coated or uncoated. The standard applies to bolts with strength classes less than or equal to 1,275 MPa, ensuring reliable performance in aerospace applications.
This standard is essential for engineers, manufacturers, and quality control specialists involved in aerospace fastener systems, providing precise dimensional guidelines to support the design, manufacture, and inspection of these critical components.
Key Topics
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Bolt Design
Covers bolts with reduced bihexagonal heads, optimizing strength while reducing weight and space inclusion in aerospace assemblies.
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Thread Specifications
Focuses on long-length MJ threads, with normal or pitch diameter shanks, which provide enhanced performance for fastening critical aerospace components.
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Material and Coating
Bolts are specified to be of metallic materials, either coated (for corrosion resistance) or uncoated, catering to a range of environmental and operational requirements.
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Strength Classification
Specifies bolts with strength classes up to 1,275 MPa, ensuring the fasteners meet high tensile requirements necessary for aerospace safety.
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Dimensional Tolerances
Details the precise dimensions and tolerances for all features including head size, thread length, and shank diameter. Tolerances are defined in millimeters and comply with related ISO standards such as ISO 7913 for form and position tolerances and ISO 3353 for thread lead and runout requirements.
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Related Standards Referenced
- ISO 3353: Aerospace rolled threads requirements
- ISO 4095: Bi-hexagonal drive configurations
- ISO 5855-2: Limits for MJ threads
- ISO 7913: Tolerances of form and position for bolts and screws
Applications
ISO 12258:1998 bolts are primarily used in the aerospace industry, where high strength, precision, and reliability are vital. Practical applications include:
- Aircraft structural assemblies requiring durable and lightweight fasteners
- Engine and landing gear components where high tensile strength is critical
- Aerospace product standards development, ensuring consistency and interchangeability
- Maintenance, repair, and overhaul (MRO) operations requiring precise replacement fasteners
- Manufacturing processes demanding strict compliance with dimensional and mechanical specifications
Using bolts standardized to ISO 12258 guarantees compatibility and safety for aerospace vehicle production and operation, reducing the risk of fastener failure in high-stress environments.
Related Standards
To fully comply with aerospace fastener requirements, ISO 12258:1998 should be used alongside these key standards:
- ISO 3353:1992 - Rolls threads for aerospace bolts, specifying lead and runout characteristics critical for thread integrity.
- ISO 4095:1998 - Bi-hexagonal drives wrenching configurations, supporting proper torque application and assembly.
- ISO 5855-2:1988 - Defines limit dimensions for MJ threads in bolts and nuts, ensuring mating component fit.
- ISO 7913:1994 - Provides tolerances of form and position applicable to aerospace bolts and screws, guaranteeing dimensional accuracy.
Together, these standards form a comprehensive framework for aerospace fastener design, ensuring optimal function, interchangeability, and safety in aircraft manufacturing and maintenance.
Keywords: aerospace bolts, reduced bihexagonal head, MJ threads, bolt dimensions, aerospace fastener standards, metallic bolts, bolt strength classes, aerospace manufacturing, ISO 12258, coated bolts, uncoated bolts, aerospace engineering, bolt tolerances