Tolerances
TOLERANCES AND MANUFACTURING CRITERIA.
QAS 399 Rev 0
Issued Dec 06
Page 1 of 1
SUBJECT: TOLERANCES AND MANUFACTURING CRITERIA
1. BRITISH STANDARDS
Unless specific instructions are given to the contrary, the Company will manufacture components to the tolerances specified in the appropriate British Standard i.e.
Compression springs - BS1726 Part 1 (2002) Grade 2
Tension springs - BS 1726 Part 2 (2002) Grade 2
Torsion springs - BS 1726 Part 3 (2002)
Further details available upon request.
2. GENERAL
a) Where no standard exists for a particular product i.e Flat Clips and Wire Forms, the following general tolerances will be applied :- Linear dimensions +/- 0.5mm ( 0.020") per 100mm ( 3.937")
i.e. 55mm = +/-0.5mm. 187mm = +/-1.0mm. 323mm = +/- 2.0mm. Angles +/- 5 Degrees
b) Circlips - General controlling tolerances will be either:-
Diameter - +/- 1.5 x a + (c+20) (D+b) or,
10000,
+/- 1.5% of the Mean Coil Diameter x 1.5. - Whichever is the greatest.
D = Mean coil diameter c = Spring Index (mean diameter / wire diameter)
For imperial specifications a = 39.37 and b = 0.3149. For metric specifications a = 1000 and b = 8.
Helix - 1.5 x the wire diameter.
c) Power Springs / Rewind Springs - In the absence of other agreed tolerances, the following general control shall be applied - 1mm (0.040") per 100mm (3.937") i.e. 55mm = +/- 1mm, 187mm = +/- 2mm.
3. BLOCK TOLERANCES
Block Tolerances originally intended for machined parts are inappropriate for coiled springs, clips and wire forms. Unless specifically instructed in writing by the customer, BLOCK TOLERANCES WILL BE DISREGARDED and replaced by the appropriate tolerance specified in paragraphs ‘1’ and '2' above.
4. MANUFACTURE TO SAMPLE OR SPECIFICATION
Unless specific instructions are given to the contrary by the customer, the measured size of a sample or the size given in a specification will be taken to represent the mean dimension required. It is the responsibility of the Customer to detail dimensions of importance. All other characteristics will be taken as reference only.
5. MATING PARTS
In all cases customers are particularly advised to specify the dimensions of any closely related parts e.g. shaft diameters over which the spring is required to fit and/or hole diameters in which the spring is required to fit.
6. MATERIAL SPECIFICATION
No undertaking can be made to supply components to the same material specification as that of a customer supplied sample, unless the material specification is provided in full by the customer.
7. PERFORMANCE
No responsibility can be accepted by the company for the actual performance or fitness for purpose of components supplied unless those requirements are clearly stated in advance.
Issued December 2006
Issued by C. A. Hart
Quality Manager |
