SIST EN 754-6:2008

Overview

SIST EN 754-6:2008 is a European standard developed by CEN that specifies the tolerances on dimensions and form for cold drawn hexagonal bars made from aluminium and aluminium alloys. This standard applies to hexagonal bars with widths across flats ranging from 3 mm up to and including 80 mm. It supports industries requiring precise specifications for aluminium shapes, ensuring consistent quality for manufacturers and end-users.

The temper designations referenced in this standard comply with EN 515, which defines the mechanical properties of wrought aluminium products. SIST EN 754-6:2008 is part of the wider EN 754 series that standardizes cold drawn rods, bars, and tubes for aluminium products.

Key Topics

Dimensional Tolerances

• Width Across Flats: The standard provides detailed permissible deviations for width across flats across various size ranges. For example:

  • Up to 6 mm: tolerance of -0.08 mm
  • Up to 80 mm: tolerance up to -0.30 mm depending on size category

• Corner Radii: Maximum corner radius is defined for different size ranges to maintain uniform hexagonal shape precision:

  • 3 to 8 mm: max radius 0.2 mm
  • Up to 80 mm: radius increases progressively to a maximum of 0.8 mm

• Length Tolerances: When fixed lengths are specified, tolerance depends on the length category:

  • For lengths ≤ 2,000 mm: +5 mm / 0 mm
  • Between 2,000 to 5,000 mm: +7 mm / 0 mm
  • Over 5,000 mm: +10 mm / 0 mm
    Without fixed length agreement, bars may be supplied in random lengths as negotiated.

• Squareness of Cut Ends: The squareness deviation must lie within half the fixed length tolerance, ensuring clean, precise cuts suitable for further processing.

Form Tolerances

• Straightness: The standard sets limits on straightness deviations measured along the bar length. For bars ≥ 10 mm width across flats, a maximum allowed deviation of 2 mm per meter length and a localized kink of 0.6 mm per 300 mm length are specified.

• Convexity and Concavity: These are controlled within the width across flats tolerances to maintain proper hexagonal geometry.

• Twist: Twist tolerance is defined per 1,000 mm of bar length, with values depending on size category:

  • 10 to 30 mm: max total twist 2°
  • 30 to 80 mm: max total twist 2.5°
    Twist tolerances for bars below 10 mm width or certain temper conditions require special agreement.

Applications

SIST EN 754-6:2008 is essential for industries where precision aluminium hexagonal bars play a critical role, including:

• Mechanical engineering: Components requiring exact cross-sections for fitting and assembly
• Aerospace and automotive: Lightweight structural elements needing strict dimensional controls
• Construction: Architectural elements benefitting from uniform hexagonal profiles
• Manufacturing: Precision machining and extrusion of aluminium parts where form accuracy impacts downstream processes

This standard ensures interchangeability, high quality, and reliability of aluminium hexagonal bars across multiple sectors by defining consistent measurement and tolerance criteria.

Related Standards

• EN 515 - Aluminium and aluminium alloys - Wrought products - Temper designations; referenced for material temper specifics.
• EN 754 series covering various cold drawn aluminium rod/bar & tube products:
  • Part 1: Inspection and delivery conditions
  • Part 2: Mechanical properties
  • Part 3: Round bars
  • Part 4: Square bars
  • Part 5: Rectangular bars
  • Part 7: Seamless tubes
  • Part 8: Porthole tubes

These related standards provide complementary specifications necessary for complete standardization across aluminium product shapes and properties.

By adhering to SIST EN 754-6:2008, suppliers and manufacturers of aluminium hexagonal bars ensure compliance with European quality and dimensional requirements, improving product consistency and customer confidence in critical engineering applications.