EN 12420:2014

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Baker in bakrove zlitine - IzkovkiKupfer und Kupferlegierungen - SchmiedestückeCuivre et alliages de cuivre - Pièces forgéesCopper and copper alloys - Forgings77.150.30Bakreni izdelkiCopper productsICS:Ta slovenski standard je istoveten z:EN 12420:2014SIST EN 12420:2014en,fr,de01-september-2014SIST EN 12420:2014SLOVENSKI
STANDARDSIST EN 12420:19991DGRPHãþD

EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12420
June 2014 ICS 77.150.30 Supersedes EN 12420:1999English Version
Copper and copper alloys - Forgings
Cuivre et alliages de cuivre - Pièces forgées
Kupfer und Kupferlegierungen - Schmiedestücke This European Standard was approved by CEN on 24 April 2014.
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
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12420:2014 ESIST EN 12420:2014

Recommended guidelines for design . 39 A.1 Introduction . 39 A.2 General information . 39 A.3 Guidelines for die forgings . 40 A.3.1 Drafts . 40 A.3.2 Web thicknesses . 40 A.3.3 Side wall thicknesses . 41 A.3.4 Rib design . 42 A.3.5 Cores . 43 A.3.6 Flash . 44 A.3.7 Transition radii . 45 A.3.8 Clamping lengths and clamping areas for finish machining . 47 A.3.9 Design for cross-sectional shapes . 47 A.3.10 Recommended machining allowances and total allowances . 48 A.4 Guidelines for hand forgings . 50 A.4.1 General . 50 A.4.2 General information . 50 A.4.3 Section changes and transitions . 51 A.4.4 Recommended machining allowances . 51 A.4.5 Total allowances per side of forging . 52 A.5 Guidelines for marking . 52 Annex B (informative)
Tensile properties . 54 Annex ZA (informative)
Relationship between this European Standard and the Essential Requirements of EU Directive 97/23/EC, Pressure Equipment Directive (PED) . 58 Bibliography . 59
EXAMPLE 2 Forging conforming to this standard, in material designed either CuZn40Pb2 or CW617N, for the use in contact with drinking water DW, in material condition H070, will be designated as follows:
200 pieces Forging EN 12420 — CuZn40Pb2 — DW — H070 — drawing number XY000
or
200 pieces Forging EN 12420 — CW617N — DW — H070 — drawing number XY000 6 Requirements 6.1 Composition The composition shall conform to the requirements for the appropriate material given in Tables 1 to 8. In the same tables the hot working attitude is also reported. SIST EN 12420:2014

phase for CuZn38As (CW511L), CuZn36Pb2As (CW602N), CuZn35Pb1,5AlAs (CW625N), CuZn33Pb1,5AlAs (CW626N), CuZn32Pb2AsFeSi (CW709R) and CuZn33Pb1AlSiAs (CW725R) shall be less than 3 %. The test shall be carried out in accordance with 8.4. NOTE The supplied material for forgings may not necessarily meet this requirement unless suitably heat treated. The test is intended to demonstrate that forgings produced are capable of being processed so as to pass the test requirement. Products in alloys other than CuZn21Si3P (CW724R) shall be subjected to heat treatment approximately in the range 500 °C to 550 °C after hot stamping. Should the user need to heat the material above 530 °C (i.e. soldering, brazing or welding operations) then advice should be sought from the supplier. 6.5 Residual stress level Forgings ordered in the stress relieved condition (see 4.2, 2nd paragraph) shall show no evidence of cracking when tested. The tests shall be carried out in accordance with 8.5. 6.6 Tolerances for die forgings 6.6.1 General Tolerances on dimensions and on form indicated in the drawings of a forging shall conform to the tolerances specified in this standard. If no tolerances are indicated in the drawings, the tolerances according to SIST EN 12420:2014

Key a direction of forging a direction of forging Figure 1 — Dimensions n within the die cavity Figure 2 — Dimensions t across the die parting line
Figure 3 — Die forging For recommended machining allowances and total allowances see A.3.10 and Table A.6. 6.6.2 Tolerances for dimensions within the die cavity and for dimensions across the die parting line The dimensions n and t shall conform to the tolerances given in Table 12 for material group I, Table 13 for material group II and Table 14 for material group III. SIST EN 12420:2014

Figure 4 — Area A (in mm2) = nmax × n The tolerances given in Tables 12 to 14 are also applicable for die forgings which are produced with a die cavity in one die half only facing a plane opposite die half. The tolerance need not necessarily be applied symmetrically about the nominal dimension; it may be all plus or all minus. 6.6.3 Mismatch Mismatch is not associated with a particular direction (see Figure 5). The mismatch shall be determined by reference to the largest nominal dimension nmax as viewed in the direction of forging (see Figure 5). The permissible mismatch is given in Tables 12 to 14. The maximum permitted mismatch shall be indicated above the title block or in the title block of the drawing of the forging, e.g.: mismatch max. 0,5 mm. Mismatch is not included in the tolerances for dimensions within the die cavity: the tolerances for dimensions within the die cavity and for mismatch are in this case independently applied (see Figure 6 and Figure 7). SIST EN 12420:2014

Key
Key a mismatch a mismatch b reference dimension for mismatch
Figure 5 — Mismatch Figure 6 — Intended construction Figure 7 — Permanent actual dimensions 6.6.4 Flash projection The flash projection is determined by reference to the largest nominal dimension nmax perpendicular to the direction of forging (see Figure 8). The permissible flash projection is given in Tables 12 to 14. The flash originating from the die parting line shall be trimmed by the manufacturer. Flash caused by deburring, punching or piercing or through-die inserts (see G1, G2, G3 and G4 in Figure 9) is permissible, provided that it is either removed during machining or is not objectionable if left on the finished part. This flash shall be indicated in the drawing and shall not exceed 1,5 mm.
Key a direction of forging a production by choice
b work-holder
c finished part
d permitted flash projection Figure 8 — Dimension nmax used as reference dimension for flash projection Figure 9 — Types of flash Flash projection is applied independently of dimensional tolerances. SIST EN 12420:2014

Key a mismatch b residual flash projection Figure 10 — Flash projection NOTE As the flash of type samples is generally trimmed by hand they do not represent the quality of trimming during bulk production. 6.6.5 Ejector marks If ejectors are necessary for manufacturing reasons, ejector marks can result as ridges (convex) or indentations (concave) (see Figure 11 and Tables 12 to 14). If the ejector marks may be either concave only or convex only, the total permissible variation applies. EXAMPLE — Permissible ejector mark: ± 0,3 mm; — Ejector mark only raised: + 0,6 mm; — Ejector mark only recessed: – 0,6 mm.
Key a ejector mark recessed b ejector mark raised Figure 11 — Ejector marks 6.6.6 Flatness tolerances In addition to the tolerances caused by the forging process, deviation from flatness may result from distortion, when ejecting, flash clipping, or any heat treatment. Flatness tolerances shall be determined by reference to the largest nominal dimension nmax as viewed in the direction of forging, see Figure 12 and Tables 12 to 14, and they are applied independently from all tolerances of form or position. SIST EN 12420:2014

Key nmax reference dimension for the flatness tolerance Figure 12 — Dimension nmax used as reference dimension of flatness tolerance 6.6.7 Angular tolerances The tolerances in Table 16 apply to all angles . (see Figure 13) except draft angles. NOTE For draft angles see guidelines for design in Annex A.
Key a shorter leg Figure 13 — Definition of shorter leg 6.7 Tolerances for cored forgings External diameter a and internal diameter b and depth of core penetration h for cored forgings shown schematically in Figure 14 and 15 shall conform to the tolerances given in Table 17. Circularity tolerance relating to outer diameter shall be calculated by summing the absolute values of n or tmax of Table 12. SIST EN 12420:2014

Key 1 parting line Figure 14 — Cored forgings (products cored in the forging direction)
Key 1 parting line Figure 15 — Cored forgings (products cored normally to the forging direction) 6.8 Tolerances for hand forgings 6.8.1 General The purchaser may supply nominal dimensions and/or a toleranced drawing of the forging or finished part but the tolerances on dimensions and on form shall conform to the requirements of 6.8.2 and 6.8.3. It is recommended that reference to this standard is made on drawings. SIST EN 12420:2014

Figure 16 — Dimensions t and n
Figure 17 — Dimensions + a and – a As variations in the finished diameter of discs and stepped hand forgings are difficult to control due to spread and edge distortion, no tolerances are specified. It is recommended either that these tolerances be agreed between purchaser and supplier or that these parts are supplied in the pre-machined condition. 6.8.3 Flatness tolerance In addition to the tolerances caused by the forging operation, there will be deviations from flatness due to bending, twisting or the release of stresses, particularly during any subsequent heat treatment. Forgings shall conform to the flatness tolerances given in Table 19, which are related to the length of the forging and are applied independently from dimensional tolerances. Dependent on the forging geometry (e.g. different section thicknesses) the deviation from flatness may be checked using a straightedge or surface plate. Where this is not possible, a datum plane shall be established by positioning the forging on three datum points. SIST EN 12420:2014
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