ISO 4042:2018 pdf free

ISO 4042:2018 pdf free.Fasteners一Electroplated coating systems
A conversion coating increases corrosion protection on zinc, zinc alloys and cadmium coatings. It may be a passivation (chromium VI free) or a chromatation (chromium VI containing). The conversion coating can also provide better adhesion for additional layer(s) and/or additional colour/paint.
An additional sealant/top coat (with or without integral lubricant) may be chosen to increase corrosion resistance and to achieve other specific properties (e.g. torque/clamp force properties, resistance to chemicals, mechanical resistance, aspect, colour, thermal stability, increased electrical resistance, UV radiation resistance). The selection of the nature of a sealant or top coat should be based on desired additional properties.
An additional lubricant may be applied to adjust or amend the torque/clamp force relationship.
When electroplating fasteners with specified maximum hardness equal to and above 360 HV and up to and including 390 HV (B in Tables 2, 3, 4 and 5), baking is not required provided supplemental process verification and/or product testing with regard to IHE have been performed. However, the purchaser is free to require baking generally.
For fasteners in this specified hardness range, electroplating does not pose a risk of IHE. In case of a failure in a product test, it cannot be assumed that baking the parts would have prevented such failure:
the metallurgical and physical conditions of the fastener material should be investigated for non-conformances. For more information, see B.4.
When electroplating fasteners with specified maximum hardness above 390 HV (C in Tables 2, 3 and 5), baking is required; see B.4 for minimum recommended baking temperature and duration.
The following exemptions apply:
– for fasteners which are not specified to be under tensile stress by design or standard (e.g. set screws in accordance with ISO 898-5), baking is not required (see B.2),
– induction hardened ends (e.g. for thread forming screws) shall not be considered for determining measures related to IHE in relation to Table 2, because they are normally not subjected to tensile stress provided that the end protrudes through the mating thread.
For alkaline zinc-nickel electroplatings (and nickel content from 12 % to 16 %), it is possible to avoid baking because of low risk of IHE (see B.3). The decision not to carry out baking shall be based on testing (see B.6) and be agreed between the supplier and the purchaser.ISO 4042 pdf download.