ISO 10074:2021 pdf download – Anodizing of aluminium and its alloys – Specification for hard anodic oxidation coatings on aluminium and its alloys.
When a customer wishes to be ensured that the quality of a lot or lots of anodized articles conformsto the quality specified, it is recommended that sampling be carried out in accordance with one of thesampling plans given in lSo 2859-1, using the guidance given in ISO 28590.
Thus, when a complete order, anodized in the same plant, is delivered in a series of three or more lots,a sampling plan shall be chosen on the basis of an acceptable quality limit (AQL) which represents theaverage percentage of nonconforming parts which the customer is prepared to tolerate
H.1 General
The equipment and processes employed should provide anodic oxidation coatings which meet the requirements of this document.
Unless otherwise agreed, the processing conditions should be decided upon by the anodlzer
H.2 Masking (optional)
The purpose of maxking Is to prevent the treatment of certain areas of the article, especially for articles containing parts which are not made of aluminium but of steel, brass or organic substances.
The different techniques available include:
— wax;
— varnish or paint;
— mechanical masking;
— use of traditional anodizing (such as chromic acid anodizing).
H.3 Jigging
The jigs should he made of aluminium alloy or titanium to ensure easy handling of articles and good electrical and mechanical contact.
The junction between article and jig should generally be achieved by clamping or bolting.
H.4 Degreasing
Surfaces should be clean and free from grease, oil, oxide, scale or other foreign matter. Different methods of degreasing available Include:
— degreasing by immersion in a solvent;
— degreasing using a vapour phase solvent;
— alkaline or acid degreasing.
H.5 Pickling or etching (optional)
Pickling or etching can be used to prepare a deoxidized surface. However, It Is seldom used before hard anodizing because of its effect on surface roughness. If it is necessary, an appropriate acid solution should be used.
H.6 Shot peening (optional)
Hard anodizing results in a reduction of the fatigue resistance of aluminium alloys. Shot peening before
anodizing reduces the loss in fatigue properties.
11.7 Hard anodizing
Hard anodizing is usually carried out under the following conditions:
— electrolyte: the baths are generally composed of sulfuric acid and deionized water with or without additive(s);
— agitation: a strong and uniform agitation is important to remove heat from the work pieces
— temperature: normally in the range —10 °C to +5 °C; for some special processes, the upper limit can attain +20 °C
— electric current: the current used can be direct, alternating or direct with superimposed alternating or pulsating current.
H.8 Sealing (optional)
Sealing is normally carried out when it is necessary to compromise between hardness and abrasion resistance, and the resistance of the coating to chemical attack. Scaling Is normally carried out In boiling water with or without additive(s). Sealing tends to lower the abrasion resistance of the anodic oxidation coating and can lead to microcracks.
H.9 Mechanical finishing (optional)
Lapping or grinding can be used on articles to reach a precise dimension or to improve the surface roughness.
H.lOlmpregnatlon (optional)
Coatings of molybdenum disullide, polytetrafluoroethylene (PTFE) or other approved materials can be applied over the hard anodic oxidation coating to improve the friction characteristics.
H.1 iSolution control
H.1 1.1 Anodizing bath
The composition of the anodizing bath should be controlled by chemical analysis, performed at least weekly when the bath is in use, and the solution should be maintained within predetermined limits. 11.11.2 Sealing bath
The sealing bath should be checked for pH, and conductivity or additive concentration, as appropriate. These tests should be performed at least weekly, and the solution maintained within predetermined limits.