( Continued from Page 109) points for blistering under the paint film.
Vapor degreasing is used quite widely throughout various industries and is most effective as a multi-stage operation in which the work is subjected to the triclilorethylene vapor and is then passed through a liquid spray of the same ma
terial. This sequence of operations re
sults in a fairly clean job, free of all grease and oil, and all mechanically ad
hering soil, if the sprays are properly ad
justed.
Alkali cleaning and emulsion clean
ing are other common methods of effec
tively removing grease, oil and water sol
uble m atter from m etal surfaces. These usually employ w ater solutions of com
pounds of sodium salts and other ma
terials such as w etting or emulsifying agents frequently sold under various proprietary trade names. This type of cleaning is most effective when used in a three stage washer with two w ater rin
ses and is operated at an elevated tem perature usually about 160 to 180 degrees Fahr.
Acid Cleaning Agents
Cleaning of the metal by one of the methods outlined previously may be sufficient preparation for certain types of work. However, in other cases where more is expected of the finishing system, it is necessary to further uniform and prepare the surface in order to obtain the maximum in terms of adhesion retention and moisture resistance. One method of doing this is treatm ent of the steel with an “acid-cleaning” agent, such as the familiar M etalprep or Deoxidine. There are many other acid cleaning agents of this type, most of which consist of phos
phoric acid, together with some alcohol and usually a small percentage of an active wetting agent. These compounds may be of the wipe-off or wash-off type and are effective in removing a light oxide as well as etching the metal slightly and leaving a very thin phosphate film on the steel. Their use has been quite well established in the industry.
To go one step further, we come to the use of a phosphate coating by which we mean Bonderite or its equivalent. The Bonderite process involves the treatm ent of the steel with a solution of the zinc dihydrogen phosphate which results in the formation of a mixed zinc and iron phosphate coating on the steel surface.
This coating is not very corrosion resist
ant by itself, b u t when used under a properly applied finish- it adds greatly to the prevention of corrosion and blister
ing failure by virtue of its uniformity and lack of w ater sensitivity. In addition, its texture provides b etter tooth than is obtained on a smooth steel with the re
sult that adhesion characteristics are im
proved. Several new phosphate coating m etal treatm ents have appeared on the m arket. Examples of these are Deoxi
dine No. 210 and Oakite Crys-coat No.
86, which should be considered and evaluated. Our own tests have not
pro-176 I T E E L
And ihis precision is uniform ly maintained, no matter how m any castings are poured. For, as the same molds are used regardless of the number of castings poured, there is no opportunity for dim ensions to vary. Right in the first place, these castings stay right all through the run. Metal surfaces also promote rapid cooling, w ith finer grain and. greater tensile strength.
A l u m i n u m I n d u s t r ie s h a s h a d n e a r l y 25 y e a r s ' e x p e r i e n c e i n t h e m a k in g o f p e r m a n e n t m o ld a lu m in u m c a s t i n g s . W e k n o w o f n o f o u n d r y w i t h b e t t e r f a c i l i t i e s o r m o r e m o d e r n e q u i p m e n t . A n d t o o u r c a s t i n g " k n o w h o w " w e a d d a t h o r o u g h k n o w l e d g e o f a l u m i n u m a n d it s a l l o y s .
One of our technical representatives w ill be glad to visit your plant and demonstrate how permanent mold castings cut dow n finishing time and costs.
A nd remember — Permiie permanent mold castings may b e just w hat y ou are looking for to get the jump on com petition in the postwar world. Consult us regarding your requirements.
* A L U M I N U M I N D U S T R I E S , I n c .
C I N C I N N A T I 2 5 , O H I O
C h i c a g o : 6 1 6 South Michigan A ve. Los A n g e l e s : 3 2 4 No rth Sa n P ed ro St.
D e t r o i t : 809 N e w C e n t e r Building N e w Y o r k : 9 R o c k e f e lle r Pla za A t l a n t a : 413 G ra n t Building
P E B M IT E A L U M I N U M A L L O Y C A S T I N G S
W h en your castings are made b y the permanent mold technique, y ou m ay b e sure of the utmost precision in follow in g your design. For the permanent metal mold operates w ith a dim ensional tolerance of o n ly .010", compared to -(- .030"
in sand casting.
May 7, 1945
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T O G i^A Y S O N
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gressed sufficiently to permit conclusions at this time.
In a similar manner, the treatment of zinc surfaces with a phosphate coating material, such as Bonderite, results in the formation of a zinc phosphate coat
ing layer over the zinc. This coating is not affected by the acidic decomposition products of oleoresinous type vehicles, and therefore the reaction which results in poor adhesion on untreated zinc sur
faces does not have an opportunity to take placie. Lithoform No. 2 is another example of a material of this type which effectively transforms a zinc surface so that satisfactory adhesion results are ob
tained.
The surface treatment of aluminum and its alloys may require cleaning and a light chromic acid or phosphoric acid etch for certain purposes. Where greater corrosion resistance is required, partic
ularly on the heat-treated alloys such as 17S and 24S, chemical treatment by the Alrok process, or by anodizing must be used.
Recommended procedures have like
wise been established for all of the other less common metal surfaces.
Methods of Application: We have dis
cussed at some length the surface prep
aration because of the great importance of this step in the proper finishing of metal surfaces. This brings us to methods of application which, I believe, we can deal with briefly primarily to mention a few principles that merit consideration.
Various factors usually dictate the method of application that may be required and among which may be any one of the fol
lowing:
Spray—either hand or mechanical Dip—large or small dip tanks Flowcoat
Rollercoat Brush
Spraying is most generally used, al
though in this method there is consider
able loss due to atomized finish that does not reach the object being sprayed. The efficiency of spraying is largely depend
ent upon the proper adjustment of air and fluid pressure and, in hand spraying, the operator’s ability to avoid loss by cut
ting off the liquid flow promptly at the end of the stroke. Losses due to in
efficient spraying often represent 60 per cent or more of the materials sprayed, and by proper adjustment can be reduced to 35 to 40 per cent. Spraying in an electrostatic field, as developed by Rans- burg, will further reduce these losses where this type of installation is practi- cal. To avoid dust from settling on the wet freshly finished ware, tire room or booth in which spraying is done should be kept under low pressure of about
%-pound per square inch with a supply of filtered air.
Dipping, flowcoating, rollercoating and brushing are not subject to the type of loss of material incidental to spraying.
Except for brushing, the use of these other methods of application is depend
ent on factors such as the size, shape, weight and contour of the object: For TUNGTIP inserted tooth carb id e
m illing cutters a re m a d e w ith h ea v y inserts, rigidly locked into a m assive steel body. No loose, e x tra n e o u s p a rts or w ed g es.
The exclusive TUNGTIP lock a n d a d ju s tm e n t screw secures accu rate a d ju s tm e n t a n d positive position, r e g a r d l e s s of cutting pressures . . .
178 / T E E L
INCORPORATED
ERIE AVE. AND G ST., PHILADELPHIA 34, PA. n e wy o r k • Pittsburgh • Ch i c a g o