ISO 4026:2003

Overview

ISO 4026:2003 specifies the characteristics of hexagon socket set screws with flat point and applies to threads from M1.6 up to and including M24 for product grade A. The International Standard defines the dimensional requirements, permissible socket forms, thread and point features, and the reference documents required for correct application, inspection and acceptance.

Key elements in the standard include references to a figure and table of dimensions (Figure 1, Table 1) and requirements for marking, designation and acceptance. Where special or additional specifications are needed, ISO 4026:2003 directs users to select from other established International Standards.

Key Topics

• Scope and applicability: Screws covered are hexagon socket set screws with a flat point across the specified metric thread range (M1.6–M24), product grade A.
• Dimensions and tolerances: Detailed dimensional data are provided in the standard (see Figure 1 and Table 1). Socket forms, point angles and permitted machining features are described.
• Materials and mechanical properties: The standard references material and mechanical property requirements for steel, stainless steel and non-ferrous metals via linked standards.
• Surface finish and coatings: Requirements for electroplated finishes and zinc flake coatings are referenced to ISO 4042 and ISO 10683 respectively.
• Acceptance and inspection: Acceptance procedures reference ISO 3269 and surface discontinuity limits follow ISO 6157-1.
• Designation example: A typical designation shown in the standard:
  • Hexagon socket set screw ISO 4026 - M6×12 - 45H

Applications

ISO 4026:2003 is used by manufacturers, purchasing authorities, quality engineers and design teams to ensure consistent supply, interchangeability and quality control of set screws in assemblies. Typical practical benefits:

• Product interchangeability across suppliers due to standardized dimensions and tolerances
• Quality assurance using referenced acceptance and surface-discontinuity rules
• Design confidence when selecting set screws for mechanical assemblies where flat-point contact is required
• Supply chain clarity through clear designation and product grade specification

Related Standards

ISO 4026:2003 intentionally relies on and cross-references several other International Standards for threads, tolerances, mechanical properties and inspection. Key related documents include:

• ISO 225 (dimension symbols), ISO 261 and ISO 965 series (threads and tolerances)
• ISO 898-5 and ISO 3506-3 (mechanical properties for steels and stainless steels)
• ISO 4759-1 (product grade tolerances)
• ISO 4042 and ISO 10683 (surface coatings)
• ISO 3269 (acceptance inspection) and ISO 6157-1 (surface discontinuities)

For designers and procurement teams, ISO 4026:2003 provides the normative framework to specify, inspect and accept hexagon socket set screws with flat point reliably and consistently.