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Concept Guide

Fastener Standards

What a fastener standard fixes, what a standard number encodes, and how the DIN, ISO and ASME standards in this library relate to each other.

What a fastener standard is

A standard is the contract that makes a fastener a known part.

A fastener standard fixes the properties that make parts from different manufacturers interchangeable: nominal dimensions, tolerances, thread form, and the mechanical requirements a part of that size must meet. It is a specification, not a product.

That is why a dimensional question always resolves to a standard first — M14 on its own says nothing about head width, thread pitch class or property class. DIN 933 M14 does.

The three systems in this library

12 metric standards and 4 imperial standards, grouped by issuing body.

SystemBodyStandards hereThread classPages
DINDeutsches Institut für Normung (Germany)DIN 125-A, DIN 127-A, DIN 7980, DIN 912, DIN 931, DIN 933, DIN 934metric coarse8
ISOInternational Organization for StandardizationISO 4014, ISO 4017, ISO 4032, ISO 4762, ISO 7089metric coarse4
ASMEAmerican Society of Mechanical Engineers (ANSI B18 series)ASME B18.2.1, ASME B18.2.2, ASME B18.21.1, ASME B18.3UNC (inch)4
Thread class values above are read directly from standard_map_core.csv, which records 27 metric_coarse rows and 5 unc rows.

What a standard number encodes

The number identifies a family; the size identifies the instance. Examples from this library:

StandardProduct typeThread formSizes covered
DIN 933Full Thread Hexagon Head Boltfull threadM6 - M64
DIN 931Partial Thread Hexagon Head Boltpartial threadM6 - M64
DIN 934Hexagon Nutnut, coarseM6 - M64
DIN 912Socket Head Cap Screwsocket headM6 - M6
The product-type column is the library's own classification (category_display and product_label), not an external interpretation.

How a standard becomes engineering data

  1. Standard page — /library/{standard}/ carries the standard-level specification matrix, the equivalence cluster and the size navigator.
  2. Size page — each size opens its own dimensional page, for example DIN 933 M14.
  3. B3 compatibility page — each standard also has a /library/{standard}/b3/ page covering material, mechanical and surface compatibility for that standard.
  4. Cross-reference — /engineering-center/ aligns the standard against its equivalents in the other systems.

Relationships between standards

The library records four kinds of relationship, each with a confidence value.

RelationshipMeaningRecorded here
EquivalentSame part, different issuing body — interchangeable in practiceDIN 933 ↔ ISO 4017, DIN 931 ↔ ISO 4014, DIN 934 ↔ ISO 4032, DIN 125-A ↔ ISO 7089, DIN 912 ↔ ISO 4762
VariantSame family, different thread engagementDIN 933 ↔ DIN 931 (full thread vs partial thread), ISO 4017 ↔ ISO 4014
MatchingDesigned to work as a pair rather than as the same partDIN 934 ↔ DIN 125-A, DIN 934 ↔ DIN 127-A, ISO 4032 ↔ ISO 4017
Cross-systemDIN / ISO part compared with the ASME inch equivalentDIN 933 ↔ ASME B18.2.1, ISO 4017 ↔ ASME B18.2.1, DIN 934 ↔ ASME B18.2.2, DIN 127-A ↔ ASME B18.21.1, DIN 7980 ↔ ASME B18.3
Every pair above is a row in standard_map_core.csv with its own confidence value. The library records 32 such directed relationships across the 16 standards. No pair is listed here that is not in that file.

Where to continue

Data

Standards Library

All 16 standards, each with its own data page and size navigator.

 Cross-reference

Engineering Center

The DIN / ISO / ASME alignment matrix and clearance notes.

 Topic

Bolts

How the bolt standards in this library differ from each other.