1、AECMA PREN3376 A7 LOL231L 0005597 9 - A, E. C. M. A. STAN DAR D NORME A.E.C.M.A. A.E.C.M.A. NORM prEN 3376 Issue P 1 October 1989 DIT PAR LASSOCIATION EUROPENNE DES CONSTRUCTEURS DE MATRIEL AROSPATIAL 88, boulevard Malesherbes. 75008 PARIS - TL. 45-63-82-85 UDC : Key words : ENGLISH VERSION Aerospac
2、e series Limits of surface imperfections of elastomeric-toroidal sealing rings (O-rings) Srie arospatiale Limites des dfauts de surface des joints toriques en lastomre Luft- und Raumfahrt Zulssige Oberflachenfehler an o-Ringen aus Elastomeren This Aerospace Series, pre-standard has been drawn up und
3、er the responsibility of AECMA (Association Europenne des Constructeurs de Matriel Arospatial). It is published on green paper for the needs of AECMA-Members. It has been technically approved by the experts of the concerned Commission following comment by the Member countries. Subsequent to the publ
4、ication of this pre-standard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and signature of the AECMA Standard Checking Centre (NPS) and formal agreement of the Of
5、ficial Services of the Member countries it will be submitted as a draft European Standard fo CEN (European Committee for Standardization) for final vote. Nota - Extra copies can be supplied by B.N.A.E. - 8, rue Moreau-Vauthier - 92100 BOULOGNE-BILLANCOURT Edition approved for publication Comments sh
6、ould be sent within six months after the date of publication decision 5th October 1989 A.E.C.M.A. 88, Bd. Malesherbes 75008 PARIS - FRANCE C8 Chairman Mr WILLIAMS AECMA PREN337b 89 LOL23LL 0005577 2 prEN 3376 Page 3 1. SCOPE AND FIELD OF APPLICATION This standard specifies the acceptable limits of d
7、efined and assessed surface imperfections on elastomeric toroidal sealing rings (O-rings). 2. DEFINITIONS For the purposes of this standard the following definitions apply, 2.1 BACKRIND A longitudinal imperfection in which the rubber adjacent to the flash line shrinks below the level of the moulding
8、 and has a U or W like cross section with the flash frequently being ragged or torn (See figure 1). 2.2 EXCESSIVE TRIMMING A flattened and often roughened area around the inner and/or outer diameters of an O-ring caused by the trimming process. 2.3 COMBINED FLASH The combination of offset, flash and
9、 parting line projection. 2.4 FLASH A film-like material, which extends from parting line projection on inner and/or outer diameters, caused by mould separation or present due to inadequate trim. 2.5 FLOW MARKS Thread-like recesses, usually curved, of very slight depth in the unflexed state, with no
10、rmal surface texture and rounded edge, caused by incomplete flow and knit of the material (see figure 3). Radial flow marks see figure 2. 2.6 FOREIGN MATERIAL Any extraneous matter embedded in the surface of the O-ring, e.g. contamination, dirt, etc. 2.7 INDENTATIONS Depressions, usually irregular i
11、n foxm, caused by the removal of inclusions from the surface or the build up of hardened deposits on the surface of the mould cavity (see figure 6, 7 and 8). AECMA PREN3376 89 W LOL23LL 0005b00 5 = pr EN 3376 Page 4 2.8 MISMATCH The cross-sectional radius in one ring half being unequal to that of th
12、e other half, caused by the dimensional difference in mould halves. 2.3 NON- F I LL S Randomly spaced irregular shaped surface indentations having a coarser texture than the normal O-ring surface, caused by incomplete filling of the mould cavity and by air trapping (See figures 4 and 5). 2.10 OFF RE
13、GISTE3 Misalignment of O-ring halves, caused by the lateral shift of one mould cavity plate relative to the other. 2.11 OFFSET Mismatch of off register of O-ring halves. 2.12 PARTING LINE INDENTATION A shallow saucer like recess sometimes triangular in shape located on the parting line at the inner
14、and/or outer diameters, which is caused by deformation of the mould edge-at the parting line (See figure 3). 2.13 PARTING LINE PROJECTION A continuous ridge of material situated at the parting line of inner anaior outer diameters caused by worn or excessively rounded edges of the mould cavity . 3. S
15、URFACE CONDITION 3.1 The O-ring surfaces shall be free from any crack, rupture blisters or other imperfections which are greater than the limits given in Table 1 when viewed under magnification not greater than x2 with adequate illumination. 3.2 There shall be no foreign material embedded in the sur
16、face, 3.3 Flow marks, non-fills, and indentations within the limits of Table 1 shall not be allowed if:- (a) there are more than three in any 25mm length of circumference, (b) they interconnect. (cl there are more than three which are separated from each other by a distance which is Less than the ni
17、aximum limiting dimensions of such imperfection. AECMA PREN33b 89 W LOL23LL 0005b02 9 m prEN 3376 Page 6 Table 1 Limits of size for surface imperfections All dimensions are in millimeters. Sur f ace imperfection iagrammatic representation L imi t ing dimension Limit of size O-ring section diameter 2
18、,25 f flow marks is iot permissible) lr50* 1,50* 5rOO* 5,00* 5rOO* O,05 OrO5 0,05 0,05 0,05 Or15 Or25 Or40 Or63 1rO Or08 7 Or08 0110 0110 0113 C ion-f ills and indentations including parting Line indentation) L n * Or 0.03 x O-ring internal diameter, whichever is greater, subject to a maximum of 30m
19、m 1_ - prEN 3376 Page 7 lox Figure 1 - Backrind (179 623) 5x 2.5 X 1x AECMA PREN337b 87 m L0123LL 0005601.1 2 m prEN 3376 Page 8 5x 2,5 X 10 x 1x Figure 2 - Radial flow marks (179 624) 5X 2,5 X lox 1x Figure 3 - Flow marks (1 79 625) I AECMA PREN337b 87 = L0123LL 0005bOb b M prEN 3376 Page 10 e lox
20、5x 2.5 X e e 1x Figure 4 - Non fills (179 619) AECMA PREN337b _ 89 LOL23LL 0005bOi - 8 _ 9 - prEN 3376 Page 11 5x 2.5 X 10 x IX Figure 5 - Non fills (179 618) prEN 3376 Page 12 5x 2,5 X lox Figure 6 - Indentations (1 79 620) 1x 89 W lrL23LL 0005b09 I-, prEN 3376 Page 13 10 x Figure 7 - Indentations (179 621) 5x 2,s x 1x AECMA PREN3376 H 10L23LL 0005bLO B prEN 3376 Page 14 I r 1 lox 5x u 2,5 X 1x Figure 8 - Indentations (179 622) : AECMA PREN3376 8-7 -W LOL23LL R005bLL- T Mp -, prEN 3376 Page 15 I 1 5x -2.5 X ix Figure 9 - Indentations (1 79 626)
