Finishing compound for barrel and vibratory surface conditioning of ferrous and non-ferrous metals

A method and formulation for imparting a smooth finish to metallic components by subjecting the components to relative motion within a barrel or vibratory finishing machine, wherein the metallic components are immersed in a media which includes abrasive particles and an aqueous working solution of a metal finishing compound. The metal finishing compound includes a mixture of the tetrasodium salt of ethylenediaminetetraacetic acid, triethanolamine, the sodium salt of the amyl ester of sulfonated oleic acid (or the sulfate), together with a coco diethanolamine condensation amide modified with tallow fatty acid. The formulation is placed in aqueous solution, with the solution being capable of periodic or continuous partial removal for filtration to separate the aqueous solution from entrained abrasive particles.

BACKGROUND OF THE INVENTION 
The present invention relates generally to a finishing compound for barrel 
and/or vibratory surface conditioning of metallic components, and more 
particularly to such a finishing compound which is capable of use with 
formation of only modest frothing or foaming, and further which is capable 
of either continuous or periodic filtration in order to separate entrained 
abrasive particles from the aqueous solution. 
The surface conditioning of metallic components, including both ferrous and 
non-ferrous metallic components is a widely utilized process in industry. 
Mass production requires means for conditioning surfaces for either 
enhancing the appearance, or preparing the surface for subsequent chemical 
treatment, such as electroplating or painting, as well as meeting other 
miscellaneous functional requirements. In order to render such an 
operation economically feasible, means must be provided to economically 
condition the surfaces of the metallic components without sacrificing 
quality. 
Because of the economic demands of material treatment, metal surface 
conditioning must be undertaken with a view toward minimizing expenditure 
of time and materials. Also, the environment must be protected from 
exposure to materials which may contaminate or otherwise deleteriously 
affect surface or subterranean water. The method and formulation of the 
present invention is one which permits surface conditioning to be 
undertaken without adversely affecting either the product quality or the 
environment. 
Barrel and/or vibratory surface treatments have become widely recognized as 
a processing operation of industry. These techniques are widely accepted 
and have replaced in whole or in part such other labor intensive 
operations as belt sanding, wire brushing, hand scraping, electric or 
air-powered hand grinding, abrasive blasting, hand filing, buffing and the 
like. Those finishing operations which may be performed by either barrel 
or vibratory processing include cleaning, de-scaling, grinding and 
polishing, with this form of finishing being undertaken and completed 
without adversely affecting the quality of the parts being treated. 
Normally, the parts to be treated are loaded into a receptacle for the 
barrel or vibratory element along with a finishing media and an aqueous 
compound. A wide variety of abrasive media are available commercially for 
this purpose, and the formulations of the present invention are adaptable 
for use with those various abrasive media which are presently utilized. 
SUMMARY OF THE INVENTION 
In connection with the present invention, the term "tumbling" is intended 
to include both barrel and vibratory surface conditioning treatments. Both 
operations subject the metallic components to relative motion within a 
finishing media, and the formulation of the present invention is adaptable 
for any of these operations. Basically, the barrel surface conditioning 
devices operate on the principle of low pressure abrasion being applied to 
the components by controlled sliding and/or rolling of the media. The 
components are immersed in an abrasive compound, along with the aqueous 
surface treating component. The barrel containing the components, media, 
and aqueous surface treating component is rotated so as to impart the 
sliding and rolling action to the individual components. Typically, the 
barrel is either a hexagonal or octagonal open top cylinder, fabricated 
from steel or other material of construction. The capacity for receiving 
loads may vary from one quart to 40 cubic feet or even larger. In certain 
installations, linings are provided to protect the work from tumbling 
against the inner wall surfaces, with these linings typically being 
rubber, neoprene, polyurethane, polyvinyl chloride. Typically, barrels are 
driven at rotational velocities of from 8 to 30 rpm, depending upon size 
and application requirements. Approximately 90% of the work is 
accomplished within the container by the sliding action which occurs when 
the abrasive media slides or rolls along the parts. 
In vibratory finishing operations, the work on the surface of the parts is 
accomplished by the peening and scrubbing action which occurs between the 
media and the parts as the container is vibrated. The vibratory or rolling 
action of the tub maintains the load contained therein in constant motion, 
with cycle times typically being shorter for vibratory than for barrel 
finishing. By way of selection of operations, the vibratory finishing 
machines are typically utilized where the components contain holes, slots, 
or other obscure areas which may not be treated through conventional 
barrel finishing. The vibratory finishing machines perform the functions 
of de-scaling, cleaning and polishing, with delicate parts having critical 
sizes being processed within this equipment. 
As previously indicated, the inner surface of the product receiving 
container may be lined, with these linings providing traction for the 
work-load movement and protection for the individual parts. In vibratory 
treatment systems, the frequency and amplitude of the energy is 
controllable, with the tub or enclosure typically moving in either a 
circular or elliptical path. Typical frequencies range from between about 
900 to 2500 cycles per minute, with the driving frequencies being coupled 
to the frequency of the drive motor, such as 1200 rpm or 1800 rpm. 
In selecting operating parameters, a higher amplitude will tend to generate 
more peening between the individual components, with a lower amplitude 
yielding primarily a scrubbing type operation. The selected variations of 
amplitude and/or frequency will determine the operation on the individual 
metallic components, with increased media pressure being obtained with a 
higher frequency motion. 
MEDIA MASS FINISHING 
The utilization of a media in finishing operations enhances the ability of 
the operation to treat small to medium-sized parts, with the treatment 
being more uniform and complete. The media available includes 
natural-occurring media such as limestone, quartz, granite, or other 
abrasive material. In another form, the abrasive material is molded in a 
pre-form, with the abrasive normally being fused or bonded aluminum oxide. 
This type of pre-form provides a relatively dense product with hard 
abrasives, thereby achieving a rapid cutting rate. Other media material 
which is typically utilized include walnut shells, ground corn cobs, 
carpet tacks, steel pins, and small metallic spheres, each providing its 
own special final surface finish. 
The utilization of pre-formed shaped media reduces resident time, 
fracturing, and provides improved cutting rates and finish qualities. The 
pre-forms permit utilization with a wider variety of part sizes and weight 
and density ranges, with the geometry of the parts being selected from 
cylinders, cones, triangles, spheres, three-point stars, and others. The 
density of the pre-forms typically range from between about 85 to 110 
pounds per cubic foot. The abrasives normally used are selected from the 
group consisting of aluminum oxide, silicon carbide, as well as mixtures 
thereof. 
The utilization of a plastic bonded media expands the range of parts which 
may be processed even further. Again, plastic bonded media is available in 
a variety of shapes and sizes, with the configurations being generally 
dissimilar to those described above. The densities are in the range of 
approximately 50 pounds per cubic foot, and include such abrasives as 
aluminum oxide, silicon carbide, quartz and silica. 
Regardless of the specific media employed, the function of media attrition 
is important. During the treating cycle, the media is subjected to 
attrition, and certain of the media is removed from the pre-form. The 
specific rate of wear is determined by inter-media friction, and generally 
not the friction existing between the individual metallic part and the 
media. Rates of attrition are determined by the size, composition and 
hardness of the media, as well as the type of operation being employed. 
Utilization of an aqueous treatment compound has been found to accelerate 
the treatment of the parts, while minimizing the rate of attrition of the 
pre-forms in the media. In this connection, the addition of an aqueous 
solution of a treatment compound will extend the life of the media by 
reducing the pressure exerted by the media upon itself, and generally 
reducing media pressures to the components being treated. In the past, a 
soapy aqueous solution or compound was utilized, however it has been found 
that soapy compounds are undesirable because of the formation of stable 
foams. 
Media-compound interaction is desirable. Specifically, when dealing with a 
plastic resin pre-form, small particles of the abrasive are released 
during the processing, thus providing a fresh surface and natural media 
attrition. While the attrition is desirable from the standpoint of metal 
finishing, problems are developed which require resolution, including 
maintaining the formation of foam or suds at a desirable level, and also 
permitting cleansing of the surface. Generally, uncontrollable foaming or 
sudsing is not desirable, since it dampens media action and limits 
filtration. Also, the release of abrasives and polyester resin solids 
tends to stabilize the suds or foam generated, thus presenting additional 
problems. Since filtration and re-processing of the fluids for utilization 
is desirable from the standpoint of cost, pollution, and the like, 
problems with frothing and foaming tend to limit the capability of 
filtration. The formulation of the present invention renders such 
filtration operations possible and they are facilitated generally with 
ease. The formulation of the present invention contains a strong 
dispersing agent for eliminating or controlling the frothing and sudsing. 
Filtration may be used to remove soil and free abrasive accumulations, 
thereby re-cleaning the compound for re-introduction into the treatment 
chamber. The compound life is extended many times over that of a single 
system. 
The active ingredients of the formulation include the tetrasodium salt of 
ethylenediaminetetraacetic acid, triethanolamine, the sodium salt of the 
amyl ester of sulfonated oleic acid (or the sulfate) as well as a 
coco-diethanolamine condensation amide modified with tallow fatty acid. 
This material is prepared to form a water-base stable concentrate, with 
the stable concentrate containing about 60% by weight of water. It will be 
understood that other concentration ranges may be useful, including a 
range of from 40 to 80%. The concentrate is diluted in the working 
solution to the extent that the working solution contains from about 0.5 
to 2% of concentrate. 
Therefore, it is a primary object of the present invention to provide an 
improved aqueous solution for use in the treatment of metallic surfaces, 
with the solution being particularly adapted for use with pre-formed 
media, and with the solution being capable of filtration and re-use. 
It is a further object of the present invention to provide an improved 
concentrate for use in aqueous solutions of tumbling operations for 
metallic components, and wherein the aqueous solution is capable of 
providing a desired and controllable level of foaming, and is, 
nevertheless, susceptible of filtration and re-constitution. 
It is yet a further object of the present invention to provide an improved 
aqueous-based formulation for metal tumbling operations, wherein the 
formulation is particularly adapted for use with pre-forms of abrasives 
and polyester resins. 
Other and further objects of the present invention will become apparent to 
those skilled in the art upon a study of the following specification and 
appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In order to provide a basis for comprehending the features of the present 
invention, the following specific example is provided: 
EXAMPLE 1 
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Ingredient Percent by Weight 
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Tetrasodium salt of ethylene- 
diaminetetraacetic acid 
0.5 
Triethanolamine 8.0 
Sodium salt of the amyl ester of 
sulfonated oleic acid 20.0 
Coco diethanolamine condensation 
amide modified with tallow 
fatty acid 10.0 
Water 61.5 
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The formulation of Example I is prepared to form an aqueous base stable 
concentrate. In the working solution, 1% of the concentrate is normally 
required for introduction of the material into a barrel or vibratory 
processing unit, although a range of from about 0.5% to 2% is 
satisfactory. The solution, during use, will provide the necessary 
physical properties to sustain maximum operation of the tumbling unit 
(either barrel or vibratory) without adversely affecting the product. 
Foaming or sudsing due to soil saponification and stabilization by 
particles of abrasives and/or polyester resins is minimized, and in fact, 
rendered controllable. The working solution may be circulated through 
filtration and separation devices for reconstitution and ultimate 
re-introduction into the treatment chamber. 
TABLE I 
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The individual components in the concentrate may be 
contained within the formulation to the following extent: 
Percent Range 
Ingredients by Weight 
______________________________________ 
Tetrasodium salt of ethylene- 
diaminetetraacetic acid 
0.2-2 
Triethanolamine 5-15 
Sodium salt of the amyl ester of 
sulfonated oleic acid 
5-30 
Coco diethanolamine condensation 
amide modified with tallow 
fatty acid 5-20 
Water 40-80 
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Such a range of components has been found to be effective in the 
formulation of workable solutions. 
DISCUSSION OF INDIVIDUAL COMPONENTS 
Tetrasodium Salt of Ethylenediaminetetraacetic Acid 
As can be appreciated, the tetrasodium salt of ethylenediaminetetraacetic 
acid is used primarily for water softening by chelation of magnesium and 
calcium cations which is responsible for water hardness. This component 
enhances the overall operation of the solution. 
Triethanolamine 
This component provides a source of alkalinity and pH control, functioning 
essentially as a buffer agent in this connection. This component also 
inhibits the formation of rust or scale of ferrous components. 
Sodium Salt of the Amyl Ester of Sulfonated Oleic Acid 
This component provides the source of particle dispersing, along with the 
yielding of a controllable low frothing or foaming solution. In the 
synthesis of this material, the oleic acid is preferably sulfonated by way 
of reaction with sulfur trioxide, and is thereafter esterified with amyl 
alcohol and finally neutralized with sodium hydroxide to form the sodium 
salt of the amyl ester of sulfonated oleic acid. As an alternate, and 
suitable as a 1:1 substitute, oleum may be used as the sulfating agent for 
the amyl oleate, with the procedures otherwise being identical. This 
reaction produces the sodium salt of the amyl ester of sulfated oleic 
acid. 
The base amyl oleate may either be purchased or synthesized by reaction of 
oleic acid with amyl alcohol under presence of an acidic catalytic agent, 
normally sulfuric acid. 
Coco Diethanolamine Condensation Amide Modified with Tallow Fatty Acid 
Coconut oil alkanol amide is commercially available. This material is 
obtained as the reaction product of refined coconut oil, animal fatty 
acid, diethanolamine, and sodium methoxide. The compound provides 
lubricity to the parts, with certain soil removing capability, along with 
rust inhibiting characteristics. This component also maintains the aqueous 
solution of the concentrate to impart a wettability of the metallic parts 
by the media, thereby providing a free-flowing of the work load within the 
tumbling unit. 
Synthesis of Coco Diethanolamine Condensation Amide Modified with Tallow 
Fatty Acid 
In order to prepare this component, which is reasonably commercially 
available, the following components are utilized: 
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Component Percent by Weight 
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Refined coco oil 39.3 
Diethanolamine 37.6 
Sodium methoxide 0.9 
Animal fatty acid 22.2 
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The refined coconut oil and diethanolamine are mixed together and heated to 
a temperature of between 220.degree.-250.degree. F. and maintained at that 
level for a period of 5 to 6 hours. The material is permitted to cool to a 
temperature of approximately 160.degree.-170.degree. F., at which time the 
sodium methoxide is added. Thereafter, the distilled animal fatty acid is 
added and the mixture is permitted to cool to room temperature. 
The diethanolamine preferably contains 98.5% diethanolamine, with 
approximately 1% of either or both triethanolamine and monoethanolamine. 
The sodium methoxide is available as a 25% mixture in methanol, with such 
materials being commercially available widely. The distilled animal fatty 
acid is a mixture of a variety of animal acids, including the following: 
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Palmitic acid 27% 
Stearic acid 18% 
Palmitoleic acid 
39% 
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Such materials are, of course, commercially available. 
The resulting synthesized product contains from 20 to 22% of free 
diethanolamine, which is desirable in the finished product.