THE "FLOWING-ON" SYSTEM.
The very latest method of finishing automobiles which have steel bodies
is that at present in use by the Ford Motor Co., Ltd., at Trafford
Park, Manchester, and elsewhere. The method is a remarkable one not
only because of the great saving of time it effects, but by reason
of the fact that the "life" of the painted or enamelled surface is
prolonged by the improved method.
Stated briefly, the process consists in coating the body with
blue-black enamel by means of gravity only; that is to say, the enamel
is placed in an elevated tank and discharged on to the work through a
flexible pipe and slotted nozzle opened by a lever which is actuated by
the thumb of the operator. Thus no spraying is required, while dipping
is out of the question, as only the outside of the body is required to
be painted.
Each coat takes two minutes to apply to the whole surface of a
four-seated Ford motor body! An achievement which justifies our use of
the word "remarkable."
But it will be convenient to explain how the present method came into
use. Until a few months ago the several undercoats were sprayed on the
work in the ordinary manner, but the finishing coat of varnish was
flowed on by the gravity apparatus now referred to. Then it was thought
that the undercoats might be applied by the same method, and some
careful experiments having been made, it was found that by dispensing
with the spraying and flowing on the coats a much more satisfactory
result was obtained. As the new method caused more paint to adhere to
the work than would be put on by the spray under ordinary conditions,
one coat, it was found, could be dispensed with altogether. There
was also less rubbing down required because of the very smooth coat
obtained by flowing on, and, above all, the time of applying the coat
was reduced to the extraordinarily short time of two minutes.
[Illustration: Fig. 119.--A CHINA FRUIT DISH DECORATED WITH THE
AIROSTYLE.]
[Illustration: Fig. 120.--TABLE COVER DECORATED WITH THE AIROSTYLE.]
The apparatus employed for this work is of the simplest character.
The car body is placed upon a platform mounted upon wheels. This is
made of exactly the right size to fit between a V-shaped metal trough
which surrounds three sides of the body and is intended to receive the
superfluous paint, a considerable quantity of which drips into it from
the body as the enamel is applied. This trough, a sketch of which is
shown in Fig. 121, is slightly inclined so that the paint which drips
off all runs to one point, where it passes through a gauze covered
orifice, descends to a small tank beneath, whence it is pumped up to
the elevated tank above and is then ready to be used again.
This elevated tank is cylindrical and holds, perhaps, 25 or 30 gallons.
It is stationed overhead some 12 or 15 feet high. From this tank
descends a flexible metal pipe or hose ending in a slotted nozzle,
opened by a lever, which is operated by the thumb of the workman and is
closed by a spring. This completes this simple though very effective
apparatus.
The body of the car is made of stamped steel which has already received
a protective coat of paint of a dull red colour, the body being placed
upon the platform or bogie and being placed in position with the
V-shaped trough surrounding it on three sides. The first or undercoat
is given by rapidly passing the slotted end of the lever valve over
the surface, upon which the paint literally pours out. The top part
receives attention first and the paint runs down over the surface,
which it covers completely, excepting perhaps here and there, where the
discharge of paint is directed, and the whole of the outer surface of
the car is, as already stated, completely covered in two minutes. This
coat dries semi-flat.
In order that the discharge pipe may be kept nearly vertical and be
moved around the car as the different sides are dealt with it is
provided, at its upper end close to the point where it joins the tank,
with a brass swivel union and a horizontal arm which swings around. A
stop-cock is also provided.
The undercoat having been applied the body is allowed to rest for a
few minutes until the dripping ceases. It is then wheeled on the bogie
across the room to an oven, in which it remains for one hour at a
temperature of 160° F. This heat is found to be sufficient to bake the
paint but is not high enough to injure the woodwork which, of course,
forms part of the body. At the expiration of the hour a little stopping
of inequalities of the surface is usually found necessary, but in any
case the surface is lightly rubbed down with fine glass paper.
[Illustration: Fig. 121.--SKETCH OF TROUGH TANK USED IN FLOWING ON
PAINT.]
The body is now brought underneath a second tank with the V-shaped
surrounding trough exactly as before described, and here it receives
another coat of enamel or paint, which in this case has a little more
body and gloss. After stoving as before and at the same temperature the
surface is carefully but rapidly rubbed down with powdered pumice stone
and water applied by means of felt pads.
There are a series of four troughs and tanks in all, corresponding
in number with the coats to be applied. From the third one the body
receives a third coat, is then baked or stoved, rubbed down with
powdered pumice and water, thoroughly cleaned off, and from the fourth
tank receives the final coat of varnish which completes the operation.
This coat of varnish is not stoved but is air-dried. The finish is a
blue-black picked out with very dark blue, and it is free from any
signs of runs or drips; in fact, no one could tell how the application
was made. As already remarked, the coats of paint are somewhat fuller
than would be the case if they were applied by spraying, and the
durability is thereby increased.
The output from this department is 70 cars a day, a number which would
be practically impossible if the work were not so splendidly systemised.
It should be observed that the varnish is applied in a separate room
from that used for the application of colour. This is done in order to
exclude dust, and also to maintain the temperature at 90° F.
In considering the essential points of this method of finishing motor
bodies, it is clear that the system might be successfully applied in
very many other industries to a great variety of goods. The apparatus
is so simple in character that no engineer would have the least
difficulty in designing a plant suitable for any particular requirement.
It must be admitted that the crux of the whole situation is the kind
of paint or enamel used. It must be sufficiently viscid to hold on to
the surface to which it is applied, sufficiently liquid to run off
freely without leaving runs, tears or "fat edges." And, above all, it
must flow out uniformly. All these conditions, however, apply also to
a dipping plant, and only require careful consideration on the part of
the paint manufacturer who has made a special study of the subject.
The varnish applied by this method must also be of a special character
so that it may flow out nicely without yielding too thick a coat,
which would be likely to lead to blemishes. Ordinary paint, enamel or
varnish, then, will not answer for this class of work, but special
products must be employed, and when these are obtained, the rest is
comparatively easy.
THE FLOCO PROCESS.
This process is in some respects similar to that above mentioned, the
difference being that it is intended principally for the application of
varnish by flowing over a painted surface done by spray. The essential
difference in the apparatus is that the varnish, instead of being
discharged by gravity, is pumped up from a tank. It is largely used in
America, and is manufactured by the DeVilbiss Manufacturing Company,
Toledo, Ohio, U.S.A. It is particularly suitable for automobile bodies
and large surfaces generally.
The process flows such materials as varnishes, enamels and japans, when
it is impracticable to spray them. It has superseded the inadequate,
inefficient flowing systems used in the past, and is also replacing
brush and dip methods as practised in many instances.
The equipment of the process comprises a 15-gallon tank, drawn from one
sheet of steel and heavily tinned; 1-6 H.P. motor, housed in, driving a
rotary pump; regulator; nozzle; electric fittings; flexible fluid hose,
and galvanized iron drain trough on rack. All parts, excepting nozzle,
hose and trough, are mounted on a castered truck for moving about. The
truck is equipped with a rack around which to wind the hose when not in
use, and a holder for the nozzle.
[Illustration: Fig. 122.--THE "FLOCO" SYSTEM OF PAINTING MOTOR BODIES.]
[Illustration: Fig. 123.--SHOW CARD DONE BY SPRAYING (STRONG).]
The finishing material, such as varnish, to be used is pumped from the
bottom of the tank by the electric motor-driven pump, in a continuous
stream, through the flexible hose, to the nozzle. The flow of material
is adjusted by the regulator, by means of which a varying amount is
not put into use and returned to the tank. In this way the flow from
the nozzle is instantly adaptable to any class of work and viscosity of
fluid without changing the speed of the motor.
When the nozzle is closed the material pumped is all forced back into
the tank through the overflow. This, serves to agitate the material; in
fact, is the only agitation necessary with material containing pigment,
such as colour varnish.
The body to be flowed is--as shown in Fig. 122--placed over the drain
trough. The operator first applies the material all along the top,
then flows it copiously over the upper half of the surface. Sufficient
material is thus, applied to insure a perfect flow to the bottom. The
job is allowed to drain into the trough which carries the material back
to the tank--here it is strained and, without the slightest waste, used
again.
Only enough material is put into the tank to take care of the work at
hand, or to handle the day's production. The maximum amount of material
exposed is 15 gallons--the tank's capacity. The nozzle will operate
satisfactorily on a gallon of material.
The tank, motor, pump and regulator are--as previously stated--mounted
on a truck fitted with casters, permitting of these parts being moved
about with the greatest of ease. Another appreciable advantage of this
style of arrangement is that an extra truck can be kept on hand and put
into immediate use in case of accident.
The cleaning of the parts is simple. The nozzle of the machine is
detached and all of the material pumped out of the tank, after which a
small quantity of naphtha--or some other similar solvent--is put into
the tank and pumped through the machine.
As the motor is only 1-6 H.P., the consumption of power is low. The
motor is made for all kinds of current, and can be attached to any
light socket.
It may be observed that the pressure tank used in this equipment
permits of the use of heavier or more viscid enamels and paints than
would be possible where gravity was depended upon. In view, however,
of the success which has been met with in the case of the Ford Motor
Company, there appears to be no reason why the Floco process should not
be used for some of the undercoats, as well as for the finishing.
The following article by M. C. Hillick appeared in "The Painters'
Magazine," of New York, and will doubtless be read with interest:--
The Willys-Overland automobile factory has recently been installed with
sixteen large enamelling furnaces or ovens having a volume of 48,000
cubic feet and a capacity of 140 tons of enamelled product every ten
hours. These ovens have been electrified and they require approximately
5,500 horse-power. For some months past the Overland Company has been
testing one of these electrically-heated ovens, and the results have,
in every way, measured up to expectations. Formerly the company, in
common with practically all other companies using enamelling or baking
ovens, employed gas as the treating medium. The ovens now electrified
are almost entirely automatic in operation. When the oven is loaded the
closing of its doors automatically throws a switch which turns on the
current. A pyrometer which can be adjusted to operate at any desired
temperature rings a bell when the proper degree of heat is reached,
thus notifying the attendant, and also automatically turning off the
current. The electrically heated oven does away with all flue gases
and with their attendant dirt and spots. It also reduces the required
volume of ventilation to the minimum, thereby eliminating air currents
and the dust which, in greater or less degree, usually accompany them.
The electrification of the ovens does away with explosions, banishes
danger from fire, and gives an assured "safety first" to the workmen.
The heat is said to be non-oxidizing and, therefore, cannot scald the
operator. The working quarters are rendered comfortable and a higher
grade of work is made possible.
[Illustration: Fig. 124.--SHOW CARD DONE BY SPRAYING (STRONG).]
While for the custom shop painter it is a long way to such equipment,
the fact that these facilities are gradually being acquired leads
to the assumption that, in the course of a few years at most, some
portion of the work coming to the shop for painting repairs will be
handled through the baking oven. In connection with this subject of
enamelling and oven baking, the various costs of paint and varnish,
it is to be noted that the excessive temperature employed in baking
is being criticised as detrimental to the finish. Recent tests are
said to have been made which show that baking paint and varnish at the
maximum temperature shortens the life of the finish. Mr. J. W. Lawrie,
of the Chemical Works of Milwaukee, Wis., has stated that, as a rule,
the lower the temperature and the longer the time the paint and
varnish is baked, the finer the appearance, service and durability of
the finish and the greater its capacity for resisting moisture. The
finish will have more elasticity and deeper lustre. Mr. Lawrie is of
the opinion that twelve hours at 180 degrees are better than five hours
at 280 degrees.
In some motor car shops, within the past two years, by the use of
baking ovens cars were painted and finished, all coats being baked, and
made ready for service in three days. However, we are not commending or
recommending this practice. For the custom shop painter, especially,
it is entirely unsuited. Nor would we recommend the baking process
for surfaces other than metal. The same disadvantages marshalled in
opposition to baking paint and varnish upon wood surfaces fifteen
years ago, or longer, still remain in evidence. For aluminium, sheet
steel or other metal panels or metal surfaces in general, the baking
process offers an opportunity for finishing work under conditions more
uniform than any which may be expected to prevail outside the oven.
An other advantage is noted in favour of oven baking. It permits the
use of more elastic materials without the aid of artificial oxidizing
agents. As compared to the present air-drying system, the oven baking
method, operated upon a conservative basis, permits the car to be
thoroughly painted and finished in six or eight days. The use of more
elastic materials--paints, colours and varnishes--has been mentioned as
a part of the oven baking method. Upon steel surfaces this is perhaps
more necessary than upon aluminium, and possibly iron. Steel has a
linear expansion double that of wood. As a matter of fact, experts in
these matters employed by the Pennsylvania Railroad assert that the
contraction and expansion of steel surfaces is much more pronounced
than the same action in wood. Materials of greater elasticity as
compared to those used in natural air-drying practice are urged.
Primers and surfacers, and the general class of foundation coats, will
require an average of three hours' baking at 200 degrees F. While some
colours require higher degrees of heat than others, 170 degrees F.
baked for, say, six hours will dry the average colour, excluding white.
The latter pigment, baked at a temperature varying from 85 to 110
degrees F., will dry properly in the course of a few hours, and retain
its natural purity of colour, whereas at a higher degree of heat the
white takes on an objectionable yellowish cast. Black, at the opposite
end of the colour pole, can be safely baked for six hours, at something
like 200 degrees F. Finishing varnishes, taking them as they run, will
bake at from 110 to 150 degrees F. for five or six hours. In all baking
practice the personal equation figures largely. Reason, good judgment,
the capacity for taking pains--all these are items of importance.
Oven baking methods are being successfully employed in some of the
large city repainting establishments. A firm near New York, for
example, using what is known as the radio process, paints and finishes
a car in three days. The cleaning of the cars is accomplished by the
use of a steam jet, a treatment which is said to cut away the grease
like magic. All surface defects following the cleaning of the car are
touched up and faced over with the necessary filling and surfacing
materials. Then these patched-up parts are rubbed down with water and
rubbing brick, and the general surface of the car is lightly rubbed
with pulverized pumice stone and water. All colour, and varnish
colour, coats are applied with a paint atomizer. This atomizer is
a pistol-shaped device operated with a trigger, the material being
sprayed from the muzzle of the barrel. The varnish colour is baked for
three hours at a temperature of from 110 to 120 degrees. From 90 to
100 degrees of humidity are provided for the oven, and by means of an
exhaust fan a fresh supply of air is furnished every three minutes.
In the oven where the varnish colour coats are baked a thermostat is
installed, which regulates the temperature. All the air entering the
oven is washed and purified by running it through a water tank before
it enters the oven. This water-washed air is forced into the oven by a
fan blower, and contact with a radiator superheats it.
In practice, the high humidity here referred to, and the water-washed
air, are mediums which serve to keep the outer surface of the drying
coat moist while the inner surface is drying, in this manner furnishing
in due time a paint film dried uniformly from top to bottom.
The finishing varnish is dried in an oven having a maintained
temperature of from 90 to 100 degrees, the humidity being regulated
at from 60 to 70 percent. This humidity is likewise found to assist a
varnish film to dry uniformly throughout.
[Illustration: Fig. 125.--DESIGN FOR SHOW CARD (STRONG).]
The treatment of the car chassis in the establishment here referred to
is quite similar to that given the body of the car. A steam treated
potash bath is provided into which fenders and other removed parts
are immersed, removing all grease and foreign substances, and even the
paint, from such parts. These parts, after cleaning, are then dropped
into tanks containing the required paints, varnish colour, etc., after
which they are taken out and drained and then consigned to an oven
maintained at a uniform degree of heat.
Other establishments having ovens installed are employing methods
designed to secure equally quick results without sacrificing any
measure of durability or appearance.
In the absence of ovens, not a few car and carriage painters are
practising the so-called hot-air method as far as possible. Successful
results are reported in many instances, the work being turned out
quicker, with an increase in lustre advised in some cases. This method
is very simple and requires no previous experience or special training.
Anyone capable of providing the necessary degree of heat--85 to 95
degrees F.--and maintaining it for eight or ten consecutive hours, can
have the benefit, in full measure, of the hot-air system. Coats of
paint, colour, varnish colour and varnish dry rapidly in a temperature
at the above degree, where the ventilation is good and a fair volume of
pure, fresh air can be constantly brought into the drying room.
NOTES ON THE CONSTRUCTION OF STOVES.
The construction of stoves for use in connection with enamelling
and baking japans generally does not properly form part of this
treatise, but a few remarks on the subject may be of service. It is
to be regretted that in only too many cases the stoves employed are
very inadequate. In some cases they are heated by gas, and the jets
cause a certain amount of discoloration. This is objectionable even
when the work is black, but if it is coloured it may lead to serious
disadvantages. In Fig. 126 is shown a sketch of what is known as the
"Perkins System of Heating." It is largely adopted in many trades for
enamelling cycle frames and parts, lamps and motor horns, etc. It is
this system which is used by Messrs. Lucas, Limited, of Birmingham, a
description of whose plant is given elsewhere. In the "Perkins" system
water is heated under pressure, and the comparatively high temperatures
required for drying and other similar purposes are obtained in a simple
but efficient manner.
The apparatus consists of circulations of hydraulic tubing, certain
proportions of which are formed into a coil and placed in a furnace
situated in any convenient position outside and below the drying
chamber. The apparatus is hermetically sealed and self-contained,
the heating water circulating from the furnace through the heating
pipes or coils and back again to the furnace without any loss through
evaporation. No pumps or moving parts of any description are required,
so that unskilled attention only is needed.
[Illustration: Fig. 126.--THE PERKINS STOVE.]
The illustration shows a simple application of the apparatus, which is
the type often employed for cycle and motor parts, bedstead frames,
electric apparatus parts, etc. The arrangement of the pipes, of course,
depends upon the class of work which has to be dealt with.
[Illustration: Fig. 127.--A TYPICAL GOODYEAR STOVE.]
[Illustration: Fig. 128.--DIPPING TROUGH.]
In Fig. 127 is shown a type of stove manufactured by Goodyear and Sons,
Churchfield Works, Dudley. The construction is a great improvement
on the old-fashioned type of enamelling stoves, which through
faulty design were responsible for great loss through radiation and
combustion. The work done in such stoves is necessarily inferior. The
firm named are among those from whom may be purchased up-to-date stoves
heated by gas (ordinary lighting or producer), steam, superheated
water, and oil, either single, double, or treble cased suitable for
purposes which a few years back were hardly dreamt of, and which may be
said to range from hairpins to bedsteads, and include munitions of war,
such as stoves for shell drying and varnishing. A very important part
of the process of stoving is the rack and trolley system of transport
in and out of the stove, which in effect means that no article is too
heavy for such process. In the production of stoves for enamelling
certain firms have made a special study of the requirements, including
those above mentioned.
[Illustration: Fig. 129.--SHOW OR MENU CARD (STRONG).]
[Illustration: Fig. 130.--EXAMPLE OF METAL DECORATION--LID OF COAL BOX
DONE WITH AIROSTYLE.]