ASTM B320-60(2019)
(Practice)Standard Practice for Preparation of Iron Castings for Electroplating
Standard Practice for Preparation of Iron Castings for Electroplating
ABSTRACT
This practice covers preparation of iron castings for electroplating and is intended to assist electroplaters in establishing and maintaining a satisfactory pre-electroplating cycle for malleable iron, gray iron, nodular iron, and white iron castings. It is also intended to indicate certain foundry practices which will facilitate subsequent finishing. The seacoal content of the molding and facing sands should be maintained at the maximum practicable limits to minimize the occlusion of sand in the surfaces of the castings. The steps for the preparation of ferrous castings for electroplating are presented. The various solutions used for the treatment of malleable and gray iron castings should be maintained by chemical analysis so far as is practicable. When the amount of soil is excessive, particularly where no precleaning is done, it may be desirable to double the cleaning and pickling facilities. Where doubling the facilities is impossible or impracticable, similar economies may be obtained to a degree by providing cleaner and pickle tanks with overflow dams, sumps and pumps with which the solution may be recirculated. In electrified tanks removable electrodes should be employed in preference to using the tank as an electrode, to facilitate inspection and cleaning. All immersion rinse tanks should be equipped with dam-type overflows to ensure skimming of oil, grease, and light dirt from the surface of the water. The paper presents the cleaning procedure cycle generally used for racked parts which will subsequently electroplated in still tanks, semiautomatic equipment, and full-automatic equipment. The most reliable test of the effectiveness of the preplating cleaning cycle is the appearance of the electroplated part and its performance in service.
SCOPE
1.1 This practice is intended to assist electroplaters in establishing and maintaining a satisfactory pre-electroplating cycle for malleable iron, gray iron, nodular iron, and white iron castings. It is also intended to indicate certain foundry practices which will facilitate subsequent finishing. Most of the practices that follow have been based on experience with malleable and gray iron. However, since they are related to the other forms, the same practices will probably apply. Nodular iron is also known as spheroidal or ductile iron, which is defined as cast iron with the graphite substantially in spherical shape and substantially free of flake graphite.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 2.1.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B320 − 60 (Reapproved 2019) Endorsed by American
Electroplaters’ Society
Endorsed by National
Association of Metal Finishers
Standard Practice for
Preparation of Iron Castings for Electroplating
This standard is issued under the fixed designation B320; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope (Warning—Use hydrofluoric acid with extreme care.)
(Warning—Sulfuric acid should be slowly added to the
1.1 This practice is intended to assist electroplaters in
approximate amount of water required with rapid mixing, and
establishing and maintaining a satisfactory pre-electroplating
then after cooling, diluted to exact volume.)
cycle for malleable iron, gray iron, nodular iron, and white iron
castings.Itisalsointendedtoindicatecertainfoundrypractices 2.2 Purity of Water—Ordinary industrial or potable water
which will facilitate subsequent finishing. Most of the practices
may be used for preparing solutions and rinsing.
that follow have been based on experience with malleable and
gray iron. However, since they are related to the other forms,
3. Foundry Practices
the same practices will probably apply. Nodular iron is also
3.1 The seacoal content of the molding and facing sands
known as spheroidal or ductile iron, which is defined as cast
should be maintained at the maximum practicable limits to
iron with the graphite substantially in spherical shape and
minimize the occlusion of sand in the surfaces of the castings.
substantially free of flake graphite.
3.2 Upon removal from the molds, castings should be
1.2 This standard does not purport to address all of the
subjected to an abrading action (such as tumbling, grit blasting,
safety concerns, if any, associated with its use. It is the
or shot blasting) to remove as much as practicable of the
responsibility of the user of this standard to establish appro-
occluded molding sand. Residual sand and scale may be
priate safety, health, and environmental practices and deter-
removed, if necessary, by treatment in various proprietary
mine the applicability of regulatory limitations prior to use.
descaling baths. These are usually based on fused caustic soda,
Specific precautionary statements are given in 2.1.
some of which use chemical oxidizing or reducing agents and
1.3 This international standard was developed in accor-
others employ electrochemical action as well. This is particu-
dance with internationally recognized principles on standard-
larly important in the case of castings that will be annealed, to
ization established in the Decision on Principles for the
prevent the burning on of sand during this operation. Castings
Development of International Standards, Guides and Recom-
that will be warped or damaged by a blasting operation may be
mendations issued by the World Trade Organization Technical
pickled in a solution containing 200 to 250 mL/L of sulfuric
Barriers to Trade (TBT) Committee.
acid to remove occluded molding sand. See Warning state-
ment in 2.1.
2. Reagents
3.3 Annealed castings should be given an additional abrad-
2.1 PurityofReagents—All acids and chemicals used in this
ing as described in 3.2 to remove any scale that may have been
practice are technical grade. Diluted acid solutions are based
formed, as well as graphitic carbon that may be present at the
upon the following assay materials:
surface.
Hydrochloric acid (HCl): 31 mass %, density 1.16
g/mL
Hydrofluoric acid (HF): 47 mass %, density 1.186
4. Nature of Cleaning
g/mL
Sulfuric acid (H SO ): 93 mass %, density 1.83 4.1 The preparation of ferrous castings for electroplating
2 4
g/mL
involves the following basic steps in the order named:
4.1.1 The removal of oils, greases, residual polishing and
buffing compounds (if any), and shop dirt by cleaning,
1 4.1.2 The removal of oxide films and scales and the loos-
This practice is under the jurisdiction of ASTM Committee B08 on Metallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on ening of surface carbon by pickling or by salt bath treatment
Pre Treatment.
(see 3.2),
Current edition approved April 1, 2019. Published April 2019. Originally
4.1.3 The removal of smut caused by 4.1.2, and
approvedin1960.Lastpreviouseditionapprovedin2013asB320–60(2013).DOI:
10.1520/B0320-60R19. 4.1.4 Activation for electroplating.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B320 − 60 (2019)
4.2 Where excessive amounts of cutting oils used in ma- pressure, oil-free air through perforated pipes at the bottom of
chining operations are present, it may be necessary to preclean the tank may also be used.
the parts before they reach the electroplating room. This may
5.7 Having the heating coils on the working side of tanks
require the use of organic solvents, vapor degreasers, washing
will assure a working surface which is free of accumulated
machines of the power-spray type, emulsion cleaners, or
grease and oil.
simple alkaline soak tanks. As short a time as possible should
elapse between this precleaning and the preplating cleaning
6. Procedure for Racked Parts
cycle so as to prevent rusting of the parts. Where control of the
6.1 The following cycle may generally be used for racked
interval is not possible, parts should be left with a slightly
parts which will subsequently be electroplated in still tanks,
alkaline or very thin organic film.
semiautomatic equipment, and full-automatic equipment:
5. Cleaning Solutions and Equipment
6.1.1 Precleaning—When castings have been subjected to
machining, polishing, buffing, or similar finishing processes, it
5.1 The various solutions used for the treatment of mal-
is desirable and frequently essential that lubricants and finish-
leable and gray iron castings should be maintained by chemical
ing compounds be removed by precleaning immediately fol-
analysis so far as is practicable, such as determining the free
lowing such operations. This is especially important when the
acid and iron concentrations of the acid baths and using tests
lubricants contain unsaturated oils which, upon air oxidation,
recommended by the manufacturer, the effective components
form films which are extremely difficult to remove. Preclean-
of the proprietary cleaning solutions.
ing methods as listed in 4.2 may be employed.
5.2 All solutions should be discarded before they lose their
6.2 Soak Cleaning—In the event precleaning of a heavily
effectiveness, based on tests and experience.
soiled part is impossible or impracticable, soak cleaning to
5.3 Whentheamountofsoilisexcessive,particularlywhere
loosen oils and greases is recommended. The bath may be
no precleaning is done, it may be desirable to double the
either an alkaline solution of such concentration as recom-
cleaning and pickling facilities.Thus, while the first of any two
mended by the supplier, and operated at a temperature as close
particular solutions becomes heavily contaminated, the second
to boiling as possible, or an emulsion-type cleaner operated as
remains relatively clean and effective for further use. When the
specified by the supplier. In either case, agitation of the
first of a pair of solutions is discarded, it is replaced by the
solution by air or solution pumping, or movement of the part,
second solution and a fresh second solution is prepared. This
will prove beneficial. The time may be 5 min or more.
system also reduces the possible carry-over of contaminants
6.3 Rinse—If the soak cleaner used is incompatible with the
such as oil and grease into subsequent solutions.
subsequent cleaner, a rinse is indicated. The supplier will
5.4 Where doubling the facilities is impossible or
normally suggest whether it is to be warm or cold, although a
impracticable, similar economies may be obtained to a degree
warm rinse (60 °C) is usually desirable following alkaline soak
by providing cleaner and pickle tanks with overflow dams,
cleaning. In any case, agitation of the rinse water is desirable;
sumps and pumps with which the solution may be recirculated.
and, in the case of cold-water rinses, a spray upon leaving the
The pump intake should be located approximately half-way
tank is beneficial. The time of rinsing depends in part upon the
down the sump to preclude returning either settled-out solid
shape of the part, but should be no less than 10 s.
dirt or surface oil and grease to the processing tank. The outlet
6.4 Anodic Cleaning—The part is made the anode in a
should be near the bottom of the processing tank at the end
solution of a properly compounded alkaline cleaner of a
opposite to the overflow dam so as to create some solution
concentration recommended by the supplier. The cleaner
turbulence (for mechanical scrubbing benefits) and to ensure
should be free-rinsing, and of high conductivity to permit a
flow of contaminated solution to the dam.
current density of 6 to 10A/dm at a tank potential of 6 to 9 V.
5.5 In electrified tanks removable electrodes should be
The solution temperature should be from 90 to 100 °C, and the
employed in preference to using the tank as an electrode, to
cleaning time from 1 to 2 min.
facilitate inspection and cleaning. To ensure good circuitry,
6.5 Rinse—Thesupplierofaproprietarycleanerwillusually
positive contacts such as an inverted V hook for round bars
should be used. In alkaline cleaner tanks, where clean contact indicatewhetherhisproductrinsesmorefreelyinwarmorcold
water. In general, rinsing should be done as described in 6.3,
is often a problem, submerged oversized steel tank rods are
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