Bsi bs a 312 1997 (iso 12260 1996)

BRITISH STANDARD AEROSPACE SERIES BS A 312 1997 ISO 12260 1996 Aerospace — Screws, pan head, internal offset cruciform ribbed or unribbed drive, stepped shank, short or medium length MJ threads, metal[.]

Aerospace —

ICS 4 0 0.2

This Bri sh Stan ard, ha ing

b en pre ared u der the

directon of the Eng ine ring

Sector Bo rd,was published

u der the authoriy of the

Stan ards Bo rd an comes

into efect on

1 Mar h 1 9

© BSI 0 -1 9

The folowing BSI references

relate to the work on this

stan ard:

Commi e reference ACE/12

Draft for comment 9 / 71 7 1 DC

The prep ration of this British Stand rd was entrusted to Tech ical

Commit e ACE/12, Aerosp ce fastener and fastening sy stems, upon which

the folowing bodies were represented:

British Industrial Fastener Fed eration

Ministry of Defence

Society of British Aerosp ce Comp nies

Am endm ents is ued sinc publ cation

Pag e

National foreword

This British Stand rd has be n prep red b Technical Commit e ACE/12 It is

id entical with ISO 1 26 :19 6, A er ospa ce — Scr ews, pa n hea d , inter na l o fs t

cr ucifr m r ib ed o u r ib ed d r ive, step ed sha nk, shor t o med ium length MJ

thr ea d , meta llc ma ter ia l, coa ted o u coa ted , str ength cla ss s le s tha n o equa l

to 1 100 MPa — D imensions, publshed b the International Org anization for

Stand ard ization ( ISO)

A British Stand ard d oes not purport to includ e al the neces ary prov isions of a

contract User of British Stand rd s are responsible for their cor ect a plcation

Com pl anc with a British Standard does not ofitself confer im m unity

f om leg al o l g ations

Cros - referenc s

Publcation r f r ed to Cor esp nding British Stand rd

ISO 28 -2:19 8 BS EN 2028 -2:19 3 ISO system o lmis a nd fi s.Ta ble

o sta nd a r d toler a nc gr a d es a nd lmi d evia tions f r

hole a nd sha fts

( Identical

ISO 3 5 :19 2 BS 2A 231:19 3 R oled thr ea d s f r bol s Lea d a nd

r unout r equir ements

( Identical

ISO 5 5 -2:19 8 BS 629 A er ospa ce MJ thr ea d s

Part 2:19 4 Limi d imensions f r bol s a nd n ts

( Identical

ISO 7 13:19 4 BS 2A 29 :19 5 B ols a nd s r ews, metr ic Toler a nc s o

f r m a nd posi ion

( Identical

Sum mary of pag es

This document comprises a f ont cov er, an insid e font cov er, p g es i an i ,

p g es1 an 2, an insid e b ck cov er and a b ck cov er

This stand rd has be n up ated ( se copy rig ht d ate) an ma hav e ha

amendments incorporated This wi l be ind icated in the amendment ta le on

theinside f ont cov er

1 Scope

This International Stand rd specifies the

d imensions of p n head s rews with internal ofset

c uciform rib ed or u rib ed driv e, step ed shan ,

short or med ium leng th MJ threa s, in metal c

material, coated or u coated, with streng th clas es

les than or eq ual to 1 10 MPa

This International Stand ard is a plca le to the

compiation of aerosp ce product stand rd s

2 Normative r f r nces

The fol owing stand ard s contain prov isions which,

throug h reference in this text, constitute prov isions

of this International Stand ard At the time of

publcation, the editions ind icated were v ald All

stand ards are subject to rev ision, and p rties to

ag re ments b sed on this International Stand rd

are encourag ed to inv estig ate the pos ibi ty of

a ply ing the most recent editions of the stand rds

indicated below Member of IEC and ISO maintain

reg ister of cur ently v ald International Stand ards

ISO 28 -2:19 8, ISO system o lmis a nd fis —

Pa r t2: Ta ble o sta nd a r d toler a nc gr a d es a nd

lmi d evia tions fr hole a nd sha fts

ISO 3 5 :19 2, A er ospa ce — R oled thr ea d s fr

bols — Lea d a nd r unout r equir ements

ISO 5 5 -2:19 8, A er ospa ce — MJ thr ea d s —

Pa r t2: Limi d imensions fr bols a nd n ts

ISO 7 13:19 4, A er ospa ce — B ols a nd s r ews,

metr ic — Toler a nc s o fr m a nd posiion

ISO 1427 :—

1)

A er ospa ce — Dr ive , inter na l, o fs t

cr ucif r m, r ib ed — Metr ic s r ie

ISO 1427 :—

1)

A er ospa ce — Dr ive , inter na l, o fs t

cr ucif r m — Metr ic s r ie

3 Config uration and dimensions

Se Fig ure 1 an Ta le 1 Dimensions and

tolerances are ex res ed in mi imeter They are

a plca le after any sur ace coating , but before the

a plcation of any lubricant

Tolerances of form an position are specified in

ISO7 13

1)

To b published

Fig ure 1

Ta le 1

Diameter

c de

T re d a D

1 D

2 D

3 D

4 D

5

1 c

L

2

Driv

c de d

T re d

h1 b

m in nom tol h1

b

nom tol ± 0,2 short medium nom tol m a x m in

0 0 MJ ×0,8 – 4h6h 3,9 8,7 1 3,4

± 0,5

0 0 MJ ×1 – 4 h6h 4,6 1 ,7 1 4,2 6

0,7

3,6 3 to 6 1 1

0,7

2,4 0,6

R6

1 0 MJ 0×1,2 – 4h6h8,3 1 ,7 2 7,9 1 0,8 6 5 to 1 01 ,5 2 ,5 0,8 4 1 R1

1 0 MJ 2×1,2 – 4h6h1 ,3 2 ,7 2 9,8

1 0,9 7,2 6 to 1 01 2 ,5 0,9 4,8 1,2 R1

a

In acordance wih ISO 5 5 -2

b

Se ISO 2 6-2

c

Inc ements:

1 for L

1

< 3

2 for 3 < L

1

< 1 0

4 for L

1

> 1 0

d

In ac ord ance wih ISO 1 2 5 or ISO 1 2 6

0

0, –

+ 0,2

0

0

, –

0

0,2 –

0

, –

0

3 , –

0

0, –

B

3 9Ch isw i ckH i g hR oa

Lon don

W44 AL

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