ASTM B – Designation: B – 99 (Reapproved ) Endorsed by American Electroplaters’ Socie. Find the most up-to-date version of ASTM B at Engineering International Auto and Engineering Works (IAEW), a year-old company based in Mumbai, follows the (The American Society for Testing and Materials) ASTM.
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Stop-off materials, when used, should be applied carefully in order to avoid contaminating signi? Various metals are electroplated for decorative or engineering finishes. These all have a bearing on the proper functioning of cleaners. Often, depending asym on the amount and type of soil on the astm b as astm b, one or more of these stages may be eliminated or modified.
For cold-solvent operations, adequate ventilation must be provided in the work area. Foaming after soap accumulation also limits spray pressure. In-process cleaning or even a hot-water? Too high a current density when electrocleaning cathodically will cause electroplating out of dissolved metals and some colloids as a smut.
There are exceptions to this rule, as in electrocleaning lead, magnesium, nickel, silver, and some stainless steels.
Iron, steel, magnesium, and copper have better tolerance to alkaline cleaners. These stages are discussed in three parts:. Special low-foaming surface-active agents are generally used. Check the age of the cleaner.
It is not effective on metallic salts, scale, carbon asstm, many inorganic soldering or welding? Users of this aztm are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.
Oxygen gas is evolved on the surface. Because of the low cost of diluted emulsion cleaners, it is economical to discard these baths asmt frequent intervals.
Additions of rust asgm or of alkali cleaners can be made to the water phase. For more specific safety precautionary statements see Sections 11 and Notes are optional and private. Asfm this reason, it frequently is desirable to use low concentrations of cleaner, for example, astmm. Cleaners should be discarded periodically because of accumulation of debris, etc. Too high a pH will result in lowering of the bacteria action, and oil will be built-up.
On ferrous alloys no inhibition is required. The higher temperatures remove soils more quickly and effectively, but caution must be used with cleaners containing organics of low? Various metals are electroplated for decorative or engineering finishes. A continuous sheet of water on the part usually indicates a clean surface.
The organic chelating agents are stable and offer another advantage over the polyphosphates in that they solubilize light oxide? This action, plus subsequent acid dip, before electroplating, removes disturbed metal surfaces and promotes better adhesion.
For more specific safety precautionary statements see Sections astj and Not all of the processes that have been reported astm b successful are described, but rather b32 basic ones that have had the wi Usually, even with light soils, it is advisable to retain multistage cleaning, thereby increasing the life and efficiency of the cleaning solutions.
Part I —Precleaning use of a solvent, emulsion, or alkaline spray to remove the bulk of the soil. The common electroplates applied are usually copper, nickel, and chromium for decorative and functional uses.
ASTM B322 – 99(2014)
If steam coils are used, check for leaks diluting the solution. This time is shortened if agitation is vigorous, temperatures high, and concentration high. The cleaner should be formulated for its method of application. Roughness also may be caused by incomplete rinsing of alkaline soak or electrocleaners due to excessive water hardness or an exhausted cleaner bath. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every?
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The nozzles should be periodically cleaned. If possible, design of parts should avoid small indentations that tend to trap solid particles or buffing compositions. The chemical activity of the metal is an important and determining factor in cleaner selection. Soap-base emulsion cleaners can cause difficulties where acidic soils are introduced; here mixed alkalies and emulsion cleaners can also require water conditioning in hard-water areas to avoid precipitation of hard-water soaps.
If the same trouble is evident on these parts, it can usually astn concluded that the trouble is in the electroplating baths or elsewhere and not in the preparatory part of the cycle.
With some cleaners, adequate rinsing is difficult to obtain after the cleaner has dried on the work. Alkaline cleaners vary in this respect; much depends on the amount of soil present on the work being cleaned. Living microbes break down organic compounds, such as oil and grease into carbon dioxide and water and the cleaners, if properly maintained, may run for years without changing the bath at all. Alkaline chelated derusting and cleaning solutions, alone or with sodium cyanide, used as a soak or electrocleaner, are often preferred before electroplating on ferrous alloys.
Such insoluble soaps adhering to surfaces decompose in subsequent acid dips and leave objectionable? Some surface defects may not show up until cleaning and electroplating cycles are completed.
The use of automatic auxiliary stills in conjunction with the degreaser allows continuous cleaning operation and solvent astk. Increasing attention to reduction of stream pollution throughout the country means that this factor is a more decisive one in selection of cleaning materials.
Certain precious-metal surfaces, such as gold, may exhibit water break, even though clean. Proper ventilation g322 be overstressed because workmen will often discard a recommended gas mask. Negatively charged ions and colloids are attracted to the parts.