SIST EN 3725:2005

Aerospace series - Screws, pan head, six lobe recess, normal shank, long thread, in titanium alloy TI-P64001, anodized, MoS2 coated - Strength class: 1 100 MPa (at ambient temperature)

This standard specifies the characteristics of pan head screws with six lobe recess, threaded to head, in TI-P64001, anodised, MoS2 coated, for aerospace applications.
Strength class: 1 100 MPa
NOTE   Taking account of the recess geometry, the strength class to be used for the seating torque calculation shall not be greater than 900 MPa.

Luft- und Raumfahrt - Zylinderschrauben, Sechs-Bogenzahn, langes Gewinde, aus Titanlegierung TI-P64001, anodisiert, MoS2-beschichtet - Festigkeitsklasse: 1 100 MPa (bei Raumtemperatur)

Série aérospatiale - Vis a tete cylindrique, a empreinte six lobes, fut normal, filetage long, en alliage de titane TI-P64001, anodisées, revetues MoS2 - Classe de résistance : 1 100 MPa (a température ambiante)

Aerospace series - Screws, pan head, six lobe recess, normal shank, long thread, in titanium alloy TI-P64001, anodized, MoS2 coated - Strength class: 1 100 MPa (at ambient temperature)

General Information

• Status: Published
• Publication Date: 31-May-2005
• ICS: 49.030.20 - Bolts, screws, studs
• Technical Committee: SS SPL - Technical Board for the general field
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Jun-2005
• Due Date: 01-Jun-2005
• Completion Date: 01-Jun-2005
• Ref Project: EN 3725:2004 - Aerospace series - Screws, pan head, six lobe recess, normal shank, long thread, in titanium alloy TI-P64001, anodized, MoS2 coated - Strength class: 1 100 MPa (at ambient temperature)

Relations

• Replaces: SIST EN 3725:2004 - Aerospace series - Bolts, pan head, six lobe recess, normal shank, long thread, in titanium alloy TI-P64001, MoS2 coated - Classification: 1 100 MPa (at ambient temperature)
• Effective Date: 01-Jun-2005

Overview

EN 3725:2004 is a CEN aerospace standard that specifies the characteristics of pan head screws with a six-lobe recess, normal shank and long thread, manufactured in titanium alloy TI-P64001, anodized and coated with molybdenum disulphide (MoS2). The standard applies to aerospace fasteners requiring high strength and low-friction surface treatment. The nominal material strength is 1 100 MPa (at ambient temperature), with a specific note on seating torque calculation.

Key factual points from the standard:

• Fastener type: pan head screws, six-lobe recess (threaded to head)
• Material: titanium alloy TI-P64001 (annealed bar/wire for forged fasteners referenced)
• Surface finish: anodized, then MoS2 dry-lubricant coating
• Strength class: 1 100 MPa (note for seating torque below 900 MPa)
• Dimensions and tolerances: given in figures and Tables 1–2 (values apply after anodizing but before MoS2 coating)

Key Topics

• Design and dimensions: The standard includes configuration, dimensions, tolerances and masses (see Figure 1, Tables 1 and 2). Dimensions are expressed in millimetres and apply after anodizing but prior to MoS2 coating.
• Material and treatment: Material specification is referenced to EN 3813 for TI-P64001 and EN 2491 for MoS2 coating methods.
• Strength and torque guidance: Material tensile strength is 1 100 MPa; however, "the strength class to be used for the seating torque calculation shall not be greater than 900 MPa", acknowledging recess geometry and seating behavior.
• Designation and marking: Example designation format: SCREW EN3725-080060. Marking styles for thread codes are specified and linked to EN 2424.

Applications

This standard is intended for aerospace applications where lightweight, high-strength, corrosion-resistant, and low-friction threaded fasteners are required. Typical practical benefits include:

• Weight reduction by using titanium alloy fasteners
• High tensile performance at ambient temperature (1 100 MPa class)
• Improved assembly reliability from MoS2 dry-lubricant coating (reduced friction, controlled torque)
• Consistent interchangeability and traceability via standardized designation and marking

Designers and maintenance engineers use EN 3725:2004 when selecting or specifying pan head six-lobe screws for airframe assemblies, secondary structural attachments, and other aerospace hardware where the specified thread forms and surface treatments are required.

Related Standards

Relevant normative references and related standards cited by EN 3725:2004 include:

• ISO 3353-1 (rolled external threads)
• ISO 5855-2 (MJ threads)
• EN 2424 (marking of aerospace products)
• EN 2491 (MoS2 dry lubricants - coating methods)
• EN 3813 / EN 3818 (TI-P64001 and bolts technical specs)
• EN 3905, EN 3911 (six-lobe recess definitions)

For procurement, engineering and quality control, consult the referenced tables and figures in EN 3725:2004 for exact thread codes, length codes, tolerances and mass data.

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2005
1DGRPHãþD
SIST EN 3725:2004
Aerospace series - Screws, pan head, six lobe recess, normal shank, long thread,
in titanium alloy TI-P64001, anodized, MoS2 coated - Strength class: 1 100 MPa (at
ambient temperature)
Aerospace series - Screws, pan head, six lobe recess, normal shank, long thread, in
titanium alloy TI-P64001, anodized, MoS2 coated - Strength class: 1 100 MPa (at
ambient temperature)
Luft- und Raumfahrt - Zylinderschrauben, Sechs-Bogenzahn, langes Gewinde, aus
Titanlegierung TI-P64001, anodisiert, MoS2-beschichtet - Festigkeitsklasse: 1 100 MPa
(bei Raumtemperatur)
Série aérospatiale - Vis a tete cylindrique, a empreinte six lobes, fut normal, filetage long,
en alliage de titane TI-P64001, anodisées, revetues MoS2 - Classe de résistance : 1 100
MPa (a température ambiante)
Ta slovenski standard je istoveten z: EN 3725:2004
ICS:
49.030.20 Sorniki, vijaki, stebelni vijaki Bolts, screws, studs
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 3725
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2004
ICS 49.030.20 Supersedes EN 3725:2003
English version
Aerospace series - Screws, pan head, six lobe recess, normal
shank, long thread, in titanium alloy TI-P64001, anodized, MoS2
coated - Strength class: 1 100 MPa (at ambient temperature)
Série aérospatiale - Vis à tête cylindrique, à empreinte six Luft- und Raumfahrt - Zylinderschrauben, Sechs-
lobes, fût normal, filetage long, en alliage de titane TI- Bogenzahn, langes Gewinde, aus Titanlegierung TI-
P64001, anodisées, revêtues MoS2 - Classe de résistance P64001, anodisiert, MoS2 beschichtet - Festigkeitsklasse:
: 1 100 MPa (à température ambiante) 1 100 MPa (bei Raumtemperatur)
This European Standard was approved by CEN on 11 September 2003.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 3725:2004: E
worldwide for CEN national Members.

Contents                                                                        Page

Foreword.3
1 Scope .4
2 Normative references .4
3 Required characteristics.4
4 Designation .9
5 Marking .9
6 Technical specifications .9
Foreword
This document (EN 3725:2004) has been prepared by the European Association of Aerospace
Manufacturers - Standardization (AECMA-STAN).
After enquiries and votes carried out in accordance with the rules of this Association, this Standard has
received the approval of the National Associations and the Official Services of the member countries of
AECMA, prior to its presentation to CEN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by May 2005, and conflicting national standards shall be withdrawn at
the latest by May 2005.
This document supersedes EN 3725:2003.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
and United Kingdom.
1 Scope
This standard specifies the characteristics of pan head screws with six lobe recess, threaded to head, in
TI-P64001, anodized, MoS coated, for aerospace applications.
1)
Strength class: 1 100 MPa
NOTE Taking account of the recess geometry, the strength class to be used for the seating torque calculation shall
not be greater than 900 MPa.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3353-1, Aerospace – Lead and runout threads – Part 1: Rolled external threads
ISO 5855-2, Aerospace – MJ threads – Part 2: Limit dimensions for bolts and nuts
EN 2424, Aerospace series – Marking of aerospace products
EN 2491, Aerospace series – Molybdenum disulphide dry lubricant
...