SIST EN 4268:2014

Aerospace series - Metallic materials - Heat treatment facilities - General requirements

This European Standard covers the general requirements for heat treatment facilities processing semi-finished products and parts in metallic aerospace materials.
It defines the terms used herein and describes the test procedures and requirements for mandatory tests of heat treatment facilities. It also serves as an aid in the surveillance and approval of heat treatment facilities.
This standard applies to all types of heat treatment facilities, including those using direct or indirect heat transfer and liquid or gaseous heating media, with our without circulation, and to vacuum furnaces.

Luft- und Raumfahrt - Metallische Werkstoffe - Wärmebehandlungsanlagen - Allgemeine Anforderungen

Diese Europäische Norm umfasst die allgemeinen Anforderungen an Wärmebehandlungsanlagen, in denen Halbzeug und metallische Teile für die Luft- und Raumfahrt hergestellt werden.
Sie definiert die verwendeten Begriffe und beschreibt Verfahren zur Überprüfung von Wärme¬behandlungs-anlagen und zugehörige Anforderungen. Sie dient außerdem als Hilfe bei der Überwachung und Zulassung von Wärmebehandlungsanlagen.
Diese Norm ist auf alle Arten von Wärmebehandlungsanlagen anwendbar, einschließlich solcher, die direkte oder indirekte Wärmeübertragung und zirkulierende oder nicht zirkulierende, flüssige oder gasförmige Heizmedien verwenden sowie auf Vakuumöfen.

Série aérospatiale - Matériaux métalliques - Installations de traitement thermique - Exigences générales

Aeronavtika - Kovinski materiali - Naprave za toplotno obdelavo - Splošne zahteve

General Information

• Status: Published
• Publication Date: 10-Feb-2014
• ICS: 25.200 - Heat treatment
• ICS: 49.025.05 - Ferrous alloys in general
• ICS: 49.025.15 - Non-ferrous alloys in general
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 13-Jan-2014
• Due Date: 20-Mar-2014
• Completion Date: 11-Feb-2014
• Ref Project: EN 4268:2012 - Aerospace series - Metallic materials - Heat treatment facilities - General requirements

Overview

EN 4268:2012 - "Aerospace series - Metallic materials - Heat treatment facilities - General requirements" is a CEN European Standard that defines the general requirements, terminology, test procedures and mandatory tests for heat treatment facilities used on metallic aerospace materials. The standard applies to all furnace and bath types (direct/indirect heating, liquid/gaseous media, with or without circulation) including vacuum furnaces, and supports facility approval, surveillance and documentation.

Key topics and technical requirements

• Scope & definitions: clear terms such as effective working volume, temperature uniformity, working temperature and thermal equilibrium to ensure consistent interpretation across facilities.
• Category classification (A–D): furnaces/baths are grouped by maximum permissible temperature variation and working temperature ranges (code numbers 03, 07, 10, 13). Permissible variations are specified for each category and range.
• Temperature sensors & thermocouples: recording and control sensors must operate independently. Sensor accuracy follows IEC 60584-2 tolerances; thermocouple classes are specified per furnace category.
• Number & distribution of recording sensors: guidance on sensor count and placement to characterise the effective working volume; example tables indicate sensors per metre or per soaking zone.
• Temperature control & indication: requirements for setting accuracy (W) and indicating accuracy (A), including digital vs analog resolution considerations and need for reproducible set‑points.
• Heating media & quenching: selection criteria to avoid undesirable surface changes; proximity and capability of quench equipment to meet cooling profiles.
• Mandatory tests & calibration: defined test types - accuracy tests, temperature uniformity tests, instrument tests - with prescribed test frequencies, evaluation and documentation procedures to support approval and periodic checks.
• Recording & documentation: requirements for appropriate recording instruments and filing of test/approval records as part of quality assurance.

Applications and users

EN 4268:2012 is used to:

• Approve and qualify heat treatment furnaces and baths for aerospace component production.
• Define acceptance and periodic surveillance criteria for QA, calibration and facilities teams.
• Guide engineering, metallurgical and production staff in furnace selection, sensor placement and process control.
• Support auditors, certification bodies and procurement when specifying supplier capability for aerospace heat treatment.

Typical users: aerospace heat‑treatment shops, OEMs, MRO providers, quality assurance engineers, calibration laboratories and plant managers.

Related standards

• IEC 60584-2 (thermocouple tolerances) - normatively referenced in EN 4268:2012.
• Applicable material and design standards for specific metallic aerospace alloys (referenced in job‑specific documentation).

Keywords: EN 4268:2012, heat treatment facilities, aerospace heat treatment, temperature uniformity, thermocouples, vacuum furnace, furnace approval, recording sensors.

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2014
Aeronavtika - Kovinski materiali - Naprave za toplotno obdelavo - Splošne zahteve
Aerospace series - Metallic materials - Heat treatment facilities - General requirements
Luft- und Raumfahrt - Metallische Werkstoffe - Wärmebehandlungsanlagen - Allgemeine
Anforderungen
Série aérospatiale - Matériaux métalliques - Installations de traitement thermique -
Exigences générales
Ta slovenski standard je istoveten z: EN 4268:2012
ICS:
25.200 Toplotna obdelava Heat treatment
49.025.05 Železove zlitine na splošno Ferrous alloys in general
49.025.15 Neželezove zlitine na Non-ferrous alloys in general
splošno
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 4268
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2012
ICS 25.200; 49.025.05; 49.025.15
English Version
Aerospace series - Metallic materials - Heat treatment facilities -
General requirements
Série aérospatiale - Matériaux métalliques - Installations de Luft- und Raumfahrt - Metallische Werkstoffe -
traitement thermique - Exigences générales Wärmebehandlungsanlagen - Allgemeine Anforderungen
This European Standard was approved by CEN on 15 July 2011.

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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 4268:2012: E
worldwide for CEN national Members.

Contents Page
Foreword .3
1 Scope .4
2 Normative references .4
3 General .4
4 Terms and definitions .4
5 Heat treatment facility requirements .6
5.1 General .6
5.2 Category classification .6
5.3 Heating media .6
5.4 Quenching equipment and quenchants .6
5.5 Temperature sensors .7
5.5.1 General .7
5.5.2 Temperature sensor accuracy (M) .7
5.5.3 Number and distribution of recording sensors .7
5.6 Designation .8
5.7 Temperature setting (W) and indicating accuracy (A) .8
5.8 Accuracy of recorder (R), grade of accuracy (RK), resolution of recording (RA) and rate of
paper feed (PV) .9
6 Tests . 10
6.1 General . 10
6.2 Test instruments . 11
6.3 Test frequency . 11
6.4 Extent of testing . 11
6.5 Test procedures . 11
6.5.1 Accuracy test (V) and test frequency (TV) . 11
6.5.2 Temperature uniformity test and test frequency (TT) . 12
6.5.3 Instrument test (PG) and instrument test frequency (TPG) . 13
7 Test results and documentation . 14
7.1 Evaluation of temperature measurement . 14
7.2 Evaluation of temperature uniformity . 14
7.3 Documentation of test results . 14

Foreword
This document (EN 4268:2012) has been prepared by the Aerospace and Defence Industries Association of
Europe - Standardization (ASD-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 ASD,
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 April 2013, and conflicting national standards shall be withdrawn at the
latest by April 2013.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

1 Scope
This European Standard covers the general requirements for heat treatment facilities processing semi-finished
products and parts in metallic aerospace materials.
It defines the terms used herein and describes the test procedures and requirements for mandatory tests of
heat treatment facilities. It also serves as an aid in the surveillance and approval of heat treatment facilities.
This standard applies to all types of heat treatment facilities, including those using direct or indirect heat
transfer and liquid or gaseous heating media, with our without circulation, and to vacuum furnaces.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
1)
IEC 60584-2, Thermocouples — Part 2: Tolerances
3 General
The heat treatment of metallic materials produces specific material properties only if performed within
relatively narrow temperature ranges, the respective tolerances of which are specified in the applicable
standards. A heat treatment facility can therefore be used for a heat-treating operation only provided its
temperature variations over space and time remain within the specified temperature tolerance.
Proper temperature distribution in the heat treatment facility depends on e.g. the type of furnace or bath, the
heating medium, the control instruments with their feedback and run-up circuitry, and the rigging and
positioning of control sensors.
A suitable recording instrument is needed to properly monitor and document the heat treatment.
4 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
4.1
temperature uniformity
measure of the temperature variation at various points in the effective working volume after thermal
equilibrium has been reached
4.2
effective working volume
for the purposes of the present standard, the effective working volume is the working zone of the heat
treatment facility in which temperatures run within the specified maximum temperature variation and which is
available for the intended heat treatment

1) Published by International Commission Electrotechnique Internationale http://www.iec.ch/ (CENELEC
EN 60584-2).
4.3
maximum temperature variation
maximum temperature variation indicates how much the temperatures at different points in the effective
working volume are allowed to vary from the working temperature after thermal equilibrium has been reached
4.4
category classification
depending on their technical characteristics, heat treatment furnaces or baths are classified into 4 categories
A, B, C, D of different maximum temperature variation (see Table 1)
4.5
thermal equilibrium
thermal equilibrium is reached when following the temperature rise phase no validly recorded temperature
varies by more than 20 % of the maximum allowable temperature variation in the effective working volume for
the duration of one closed-loop oscillation
4.6
temperature setting
feature permitting analog or digital reproducible selection of the facility temperature set-point
4.7
correction factor
this is the correction applied to the set-point to achieve the specified working temperature
4.8
working temperature
temperature to which the heat treatment facility is brought for a certain heat treatment
4.9
working temperature range
range extending from the lowest to the highest working temperature at which the heat treatment facility is to
be operated
Note 1 to entry: A code number identifies the maximum allowable working temperature.
4.10
test temperature
agreed temperature at which the reference measurement is to be made or the temperature uniformity to be
demonstrated
4.11
temperature sensors
temperature-sensing elements for the various measuring, control and recording functions
4.12
recording sensor
temperature-sensing element of a chain of validly indicating and recording instruments
4.13
approval
for the purposes of the present standard, approval is the formal release of a facility for production heat
treatment
Note 1 to entry: It is granted if compliance with the requirements of the present standard has been demonstrated by
acceptance testing.
5 Heat treatment facility requirements
5.1 General
Heat treatment facilities shall be capable of satisfying the requirements of the heat treatment process to be
applied.
Heat treatment facilities as defined in Clause 1 shall be approved prior to their release for production heat
treatment and shall be subjected to periodic in-service checks. Approval and periodic checks shall be
performed by the responsible company quality assurance, facilities support and calibration activities.
Approval and periodic checks shall be in conformance with the requirements of Clause 6.
In the case of safety tests, the competent specialist department shall be consulted. The test results shall be
reported by the competent specialist department and filed with the heat treatment facility records.
5.2 Category classification
A heat treatment facility may fall within several categories if designed to operate in different working
temperature ranges.
Table 1 — Maximum permissible temperature variation of effective working volume
Working Maximum permissible
temperature range temperature variation
Code
°C °C
number
Category
A B C D
03 –
θ ≤ 300 ± 7,5 ± 5 ± 3
07 –
300 < θ ≤ 700 ± 10 ± 7,5 ± 5
700 < θ ≤ 1 000 ± 15 ± 10 ± 7,5 ± 5
1 000 < θ ≤ 1 300 ± 20 ± 15 ± 10 ± 5

Where a working temperature range of a facility is less than the maximum value given in Table 1, the
corresponding code number shall be indicated in the designation as outlined in 5.6.
5.3 Heating media
Heating media shall be selected so as to avoid changes in the material surfaces during the heat treatment
operation affecting the operational properties of the parts, unless such changes are allowed or specified in the
material standards or design documents. Heating media,
...