ISO 11971:2020 pdf free.Steel and iron castings — Visual testing of surface quality.
ISO 11971 covers the acceptance criteria for the visual testing of the surface of steel and iron castings.
Introduction
The surface roughness of a casting is influenced by the manufacturing process (moulding, grinding, finishing, etc.), the moulding materials used (sand, coating. etc.), the equipment available and the alloy cast. Since cast surfaces do not exhibit the same cyclic regularity as machined surfaces, it is difficult to evaluate their roughness using conventional mechanical, optical, or pneumatic devices.
The use of visual/tactile comparators is therefore preferred in these circumstances.
Moreover, in order to take account of the irregularities on as-cast surfaces, ground surfaces or other means of finishing of castings. comparators should have relatively large dimensions (greater than or equal to 15000 mm2) in order to make them more reliable and their results repeatable and consistent.
4 Ordering information
The enquiry and order should specify the following information:
a) the casting areas where the surface is to be tested should be clearly indicated on the drawing or solid model;
b) the number of castings to be tested;
c) ihe acceptance level: more ihan one acceptance level may be speciIed for different surfaces of the same casting:
d) if any types of discontinuities are unacceptable.
5 Test method
The area to be tested shall be examined without optical aids exceeding lx magnification.
The comparators define the worst or roughest condition fbr that acceptance level. 6 Acceptance criteria
a) The SCRATA comparator set is used for steel or iron castings.
h) The BNIF comparator set SI and S2 categories can be used for all alloys. Category 53 is used for steel castings only.
Table 1 lists BNIF and SCRATA comparators for surface roughness and gives the equivalency between BNIF and SCRATA comparators for surface roughness, mechanical dressing and thermal dressing.
Table 2 lists the SCRATA surface-discontinuity comparators.
Levels of acceptance for surface roughness and discoritinuities may be specified by the customer. In Annex A. Table A. I and Table A.2 give guidance on optional roughness acceptance and surface discontinuity acceptance.
Surface discontinuities not covered by this document shall he a matter of agreement between the purchaser and man ufaciurer.ISO 11971 pdf download.