I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
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Vol. 17, No. 12
Tools of the Chemical Engineer' V-Filling and Labeling Small Packages By D. H. Killeffer, Associate Editor 19
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EAST2
4 ST., ~ N~E W YORK,N. Y.
NLY when the plant engineer has his plant in har-
0
monious operation is his task complete. Both the receiving and shipping ends of the business must be brought into step with the progress of material through the manufacturing processes if operation is to go smoothly and profitably. In our tonnage industries the final preparation of the product for the consumer offers little difficulty, but where the products go into the hands of multitudes of retail buyers this part of the engineer's task assumes an importance second only to that of obtaining the highest degree of uniformity in the material itself. The consumer who spends a few cents for a few grams of a particular product is far more exacting in his ideas of the convenience and attractiveness of the package in which those few grams come to him than is the buyer of tonnage quantities t o whom packages mean little or nothing. Naturally, such exactions must be met as nearly as possible if such small purchases are to be built up into comfortable volumes of business; yet caution is required to prevent too great a diversity of packages. The sales department with its keen sense of consumer demand must, with the help of the engineer, average the vast numbers of individual whims into as few standard packages as possible in order to make profitable their production mechanically. A plant which attempted to furnish special packages to meet the desires of each consumer as a regular feature of its business would inevitably be forced out of existence by competition from automatic machinery which can only produce quantities of perfectly uniform articles. In spite of every effort at standardization of packaging the public demands its wan& conveniently put up. Almost infinite numbers of small attractive packages containing liquids, pastes, powders, and pills for every conceivable purpose must be manufactured cheaply, and in each case the highest possible degree of uniformity of output must be realized. The
Empty Bottles &eft) Are Fed t o t h i s Machine, Which Fills T h e m (Center) a n d Corks T h e m (Right)
great detail of manipulation which this kind of business involves would be impossible exoept by mechanical means and hence the extreme importance of the postulate of the mechanical engineer that any operation, no matter how complex, which must be repeated exactly a great number of times 1
Received March 17, 1925.
may be better accomplished mechanically than by hand. Some of the devices which have been developed on this basis seem able to do everything but think, and a few of them operate so efficiently in carrying out complicated cycles that their mechanical perfection might almost induce one to believe that this ability had been built into them. Liquid Packaging
The simplest solution of packaging problems has been found in putting liquids into proper bottles and cans. Dippers of proper capacities arranged in gangs to dip into a liquid r e s e r v o i r and discharge into gangs of funnels leading to a row of bottles arranged beneath are widely used to fill packages with volatile solvents. The containers are moved into place on a moving belt and a measured q u a n t i t y of liquid is poured into each b o t t l e . Although the operation and the machine for carrying it out are e x t r e m e l y simple, there is still much to be desired in the matter of sped. such These Machines Turn Powder Condevices are extentinuously i n t o Pills w i t h o u t H u m a n Intervention s i v e l v used for solvents lwhich would destroy pump packings and which are too volatile to be conveniently handled by vacuum. Exact quantities of liquid may be delivered to bottles by calibrated pumps arranged to operate a t a speed slow enough to permit the removal of full containers during the suction part of the stroke. Pumps of this kind are provided with means for varying the stroke a t the will of the operatorso that packages of different sizes may be filled on the same machine. Ordinarily, such pumps are arranged in gangs allowing a number of measured quantities to be delivered a t once through separate outlets into a row of containers run into position by a moving belt. This type of filling machine is especially advantageous for handling viscous liquids as it need not involve any considerable lengths of pipiltg. Care must be taken to prevent spilling, however, particularly if there are faults in any of the bottles fed to it. Vacuum Bottle Fillers
The most popular liquid-Wing machines and those used for the greatest variety of fluids operate by means of vacuum applied to the bottle itself. The essential part of this mer is a nozzle containing a connection to the reservoir of liquid
November, 1925
INDUSTRIAL AND ENGINEERING CHEMISTRY
to be bottled and a connection through another reservoir to a vacuum pump. The nozzle projects through a rubber stopper larger than the opening in the neck of the bottle through which the nozzle itself must be able to pass. This compound nozzle is inserted into the bottle or can to be filled until the stopper comes into tight contact with the top of .the neck. This connects the interior with the vacuum pump and with the liquid supply. As the air is drawn from the bottle the liquid is drawn in to take its place and when it has reached the desired level the excess is drawn out through the vacuum line into the supplementary reservoir. These fillers are built to be operated by hand so that they may be taken from place to place to fill carboys or large containers, and in this case the connection to the vacuum system is controlled by a lever pressed by hand by the operator. Where large numbers of identical bottles are to be filled with the same liquid, several nozzles are mounted together for filling a row of bottles beneath them. The whole mechanism is operated by a cam arrangement, so that as soon as the proper number of bottles have been pushed into place by the moving belt on which they travel they are automatically lifted up against the nozzles, the connection to vacuum opened, the bottles filled, and the vacuum finally shut off as they are again lowered to the moving belt which carries them on. This filler will not fill imperfect bottles and there is no possibility of overflow and waste of material. The bottles supplied to it must be uniform, as they are filled to a definite mark rather than with a measured quantity of liquid. This method is applicable to almost any fluid, b ~ viscous t liquids make its operation quite slow on account of the piping through which they must travel, and volatile liquids are not to be handled by vacuum if vaporization losses are considerable. With each of these fillers, as with all automatic packaging machinery, the empty containers are ordinarily moved into position and the full ones on to labeling machines on belts. By leaving them on the moving belt during the filling operation, as is often done, they are held positively in position by the friction of the belt. The moving row of containers on the belt is held during filling against a catch, which is released and permits them to move on as soon as they are full.
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tight by a lever which is part of it. The cap is put on by a machine similar to the screw-capping machine, but which, instead of screwing on the cap, simply trips this little lever. With this type of closure the cap is less liable to stick than is a screw cap and like it may be put on and off as often as desired. Packaging Solids
Powders that flow freely may be easily filled in exact amounts by machine. The devices for this purpose are of two types, one depending for its operation upon the net weight of the contents and the other upon the gross weight of the container and its contents. In principle they are the same and operate by the tripping of a scale when filled to a definite weight. The material to be packaged is fed into a chute leading to the scale which is arranged to trip and close the chute when the proper weight has been supplied to it. The opening in the chute remains closed until the full package is removed and an empty one substituted or until the contents of the scale have been emptied and the bottom of the scale pan closed again. In practice the net weighing type is usually provided with duplicate boxes, each balanced on a separate scale into which the material from the chute is alternately fed. One of these is emptying itself while the other is being fed. Between the chute and the two hoppers the flow of material is diverted from one to the other a t the proper instant. Either a flap or s flexible spout controlled in either case by the motion of the two weighing compartment8 may be used for this purpose.
Closure of Bottles
Three types of closure are used on bottles in addition to the customary crimped Crown seal, stoppers (either cork or rubber), screw caps, and a special type of cork and metal seal which permits replacement of the cap after it has been once removed. Stoppers are ordinarily loosely placed by hand in the necks of a number of bottles, which are then carried by the belt conveyor under a press which forces the whole lot home. Screw caps are put on mechanically with greater accuracy than is possible by hand. The bottles or jars are passed into a machine having a number of heads for holding the screw caps. Each head is provided with fingers for holding a single cap and with a gear drive to rotate it in the proper direction. The caps are supplied to the various heads either mechanically or by hand at the proper point in the cycle. The series of heads is placed around a revolving table and is so arranged that the cycle is complete during a single revolution of the table. At the proper point in the cycle the rotating head holding its cap is lowered by means of a cam to rest on the neck of the bottle and to screw on the cap. When the proper tension is reached the head is allowed to slip on its axle by a clutch provided for the purpose, so that it is impossible for the cap to be forced on so tightly as to damage either it or the bottle. Replaceable metal seals have come into great favor of recent years. They are held by a wire loop in the cap itself drawn
Small Quantities of Powders Are Accurately Weighed into Bottles Mechanically
Large packages are filled on a machine which provides for partial closure of the filling spout when the load is nearly complete and allows a small stream of material to bring the charge to balance. This avoids overloads and packages may be filled by such a machine continuously with an accuracy impossible to human operators. One device of this kind for filling fertilizer into sacks of one to two hundred pounds is guaranteed by the makers to supply packages containing exact weight within the accuracy of the scale used in 90 per cent of the packages and with an error of a very small fraction of 1 per cent in the remaining packages. Where the amount to be put into each package is very small the percentage of error may sometimes become slightly larger, but packages of as little as 2 ounces net contents should be filled with freeflowing material with a maximum error of much less than 1 per cent.
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I S D C S T R I J L A S D ENGIA’EERISG CHEJIISTRY
T’ol. 17, S o . 11‘
Limitations to Solid Packaging
Pills
To pass through such a mechanism a material must be able to flow freely. Nonhygroscopic materials in almost any particle size are easily packed, but if the material has a tendency to cake and clog up passages and conveyor screws it is very difficult to handle. Success has been attained, however, in handling many difficult materials by so designing the parts of the machine as to minimize contact between material and surfaces and by assisting the passage of material through the machine by brushei and otherwise.
The avidity with which the American public consume: pills has rendered the pill tile of corner druggists quite obsolete in favor of machines which form better and more uniform pills much cheaper than is possible by the old method. Pill-stamping machines which press a powder in the proper quantity into holes in a hardened steel plate between two hardened studs were first developed. These machines were quite satisfactory and are still used where small quantities are required. They operate by means of cam3 which press the powder, fed to the machine by hand, into a hole in a steel plate between hardened steel studs, and force the pili out after it is formed. Much of the operation of such a machine is by hand and it was necessary to develop a continuous automatic machine which would obviate this. The automatic machine is provided with a series of holes in a round steel disk, in which the gills arc formed instead of the single one of the early machines, and the disk as well as the studs revolve. The cams operating the stud.. are stationary and are so arranged that a complete revolution of the plate is necessary to form the pill and discharge it. The die plate may contain any convenient number of holes, usually a dozen or twenty-five, as these numbers lend themselves most readily to automatic packaging. This may be readily accomplished by the pillforming machine by connecting through gears or otherwise directly to the revolving die plate a device for placing empty packages under the chute and removing the full ones. This method is used for filling large numbers of pills promiscuously into bottles or boxes, but when it is necessary to place them in definite order in the container the problem becomeF different. This is accomplished-for instance, in filling a dozen pills into the little tin boxes which are so popular nowby a device which contains a space just large enough to hold the desired number of pills in the proper order. This space is fed from a hopper whose outlet will let through only pill? in the proper position, the whole mechanism being shaken constantly to be sure that a sufficient number of pills come into the filling space. The operator places a box against the outlet, thus tripping the closing gate and allowing only
Paste Packaging
Collapsible tin or lead tubes stamped automatically from disks of metal are becoming increasingly popular, and their use is making possible a much wider use of paste5 than was
This Machine Packages Paste without Help
formerly practicable. Tooth pastes, shaving soaps, glue, shoe polish, printing inks, salves, cold cream and cosmetics, and countless other viscous materials are being put on the market in such tubes today which until recently appeared only in jars and cans, if at all. The simplicity of the mechanical production of the tubes, which are formed by a single stroke of a heavy press, the ease with which they can be filled automatically and the convenience of this kind of a package to the consumer have been gradually working a more or less important revolution in certain fields of manufacture and marketing. After the tubes are formed in the press, trimmed, threaded, and capped, they may be filled in a number of different ways, the choice of which rests largely on the number to be filled in a given time. One filling machine consists essentially of a nozzle from which the paste is extruded and over which the tube is slipped by hand. When the tube is in place the operator’s foot starts the mechanism which delivers the proper amount of material to the tube and stops. As the paste is forced into the tube, it is gradually pushed off the nozzle into the operator’s hand and is passed on to have the bottom crimped and clamped shut. An automatic machine for doing the same thing has the tubes placed in receptacles on a moving belt by hand, cap downward, and passes them under the nozzle which automatically delivers the correct quantity of paste to each. On the same belt the tubes are passed on to a crimper, which closes them, and another part of the same machine puts on the little metal clamps which hold the crimp and prevent leakage. Finally, the finished tubes fall off into collecting baskets ready to be put into cartons.
Bottles Are Labeled Wrapped in Corrugated Board to Prevent Breakage, a n d Incl&ed in Individual Cartons on this Machine
the desired number of pills to fall out in proper order. I n the meantime more pills are being arranged to come into the feeding space as soon as the full box is removed. Labeling
Packages of most types can be easily labeled mechanically. Perhaps the simplest labeler is used for applying to round’ tin cans labels long enough to go completely around them.
Sovember, 1926
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The cans are rolled between Paraffined paper is widely two belts, first over a set of used for inclosing food and revolving disks which deposit other products which might on them a small amount of be affected by moisture or melted rosin along one side, humidity, as it lends itself and then immediately over a readily to completely waterpile of labels. The rosin proof closure by the mere sticks the paper label to the application of heat which tin and as the can rolls on bemelts the paraffin sufficiently tween its belts t'he label is to make it hold. pulled around the can. As Filling Boxes the label is pulled from the Many small articles and pack a small amount of paste packages must often be inis placed along its free edge closed in individual cartons by another set of disks rebefore they are ready for volving in paste to hold it tothe market. A d v e r t i s i n g gether when in place. A matter and instructions for brush passes over t'he seam u5e are frequently inclosed in the paper before the can with the package and other is released from between the similar complications may two belts to insure a tight ariae. However, mechanical pasting of the end of the ingenuity has reduced this label. From the elid of the operation and its variations belts the cans pass on t'o be t o p r a c t i c a l l y automatic placed in larger containers machines which receive the for shipment. T h e s e a r e contents and folded carton tousually of corrugat'ed board Tubes of Tooth Paste Are P u t into Individual Cartons Automatically gether with whatever else and are closed with silicate may be required glue or fold of soda. Comdeteness of closure is assureh by passing these packages between belts in the ends of the cartons, and delilier them ready i o be put in or stiff brushes to force the parts to be stuck together into the shipping case. One of the most remarkable of these machines is used for packaging cigarets in the popular packintimate contact. Labeling by various types of stickers is accoinplished ages of t'wenty. The machine picks up two rows of seven by means of a device similar in principle t o the ordinary auto- cigarets and one row of six, presses these into shape to form matic printing press. The bottom label from a pile, arranged a rectangular package, wraps a layer of combination paper right side up in a case, is pulled out by a set of dicks revolving and tin foil around them, and then applies the lithographed through a comb with their lower portions in the paste supply. wrapper. After this the revenue stamps are applied meThese disks coat the label with paste and put it into position chanically and the whole receives a cover of glassine paper to be picked up by the vacuum finger. This finger, which before it is dropped into the final carton. It is possible to make up a combination of machines that contains a connection to a low vacuum line, transfers it to the side of the container on which it is t o be placed and two will receive a liquid, a supply of empty bottles, corks, labels, brushes smooth it into place. This machine may be ar- cartons, and RO on at one end and turn out a t the other bottles ranged to have the packages fed to it singly by hand or on filled and properly labeled and inclosed in the final cartons a moving belt. Frequently, the labels are applied to a num- or shipping cases for the market'. S o t only is this possible ber of packages at one time by multiple unitq arranged a> without using human hands at any stage of the operation, parts of the same machine, and the most recent development hut the pon-er requirement of such a combination is almost applies two or more labels to negligible compared with the different sides of the same other needs around the averhottle a t once. age plant. The whole cycle of operations may be accomWrapping Packages plished with a minimum of attention and a maximum of The wrapping of packages accuracy and neatness. m a y b e considered along In industries in which the with labeling, as it is usual to product goes out in bottles let the wrapper serve both cycles include mechanical depurposes in many industries. vices for washing, sterilizing, The wrapping of loaves of and drying bottles automath e a d , of more or less solid ically. This part of the blocks of such materials as operation becomes extremely mince meat, and of multiimportant when the cleantudes of small packages of liness of the product is every kind is readily accomessential. plished by machines which fold the wrapping paper The most remarkable maaround the package, make the chine yet devised for elimnecessary folds for closing it, inating the human equaand supply the proper adtion from industry is one hesive to hold it in place. t h a t a u t o m a t i c a l l y sorts Fertilizer Is Weighed into Bags and Sewed
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
cigars for packaging by their color into some thirty different grades. This is accomplished mechanically by placing the cigars one by one in position to reflect light from a constant source into a potassium photoelectric cell. The variations in the e. m. f. of this cell control an electrical circuit through a series of vacuum tubes in such a way as to set a combination of pins to drop the cigar into its proper compartment as it passes on in the cycle, according to its accurately determined color. The accuracy and speed with which this machine works would be quite out of the question for a human operator. One hundred and twenty cigars per minute may be readily sorted into thirty color classes by it. Automatic machinery can profitably replace hand labor wherever there is a sufficient number of packages to be made
Vol. 17, N o . 11
and handled. Indeed, the limit below which mechanical operation is less profitable than hand operation is much lower than is commonly suspected and even a few hundred packages a day can be profitably made on machines. Where the production of small packages runs into thousands per day the economies effected by mechanical handling become very great, particularly when uniformity is essential as it is with widely advertised and trademarked articles. Acknowledgment The author's thanks are hereby extended to W. H. Gesell, of Lehn & Fink, and to the American Machine & Foundry Company, through whose kindness the accompanying illustrations are used.
Some Effects of Age on Soap Solutions' By Rosalie M. Cobb RESEARCH LABORATORY OF APPLIEDCHEMISTRY, MASSACHUSETTS INSTITUTE
INCE the aging of soap solutions is an established fact, it would seem advisable to determine the degree to which the phenomenon affects their peculiar properties. In this investigation the effect of age on emulsifying and lathering power was studied.
S
Emulsion Test The apparatus used in the emulsion tests consisted of an ordinary soda stirrer and Counce oil-sampling bottles cut off a t the neck. A stopper was wired to the arm of the stirrer for exclusion of air during the run. As a standard for the emulsifying tendency of the soap solution, the ratio of the equivalents of sodium oleate used in making a 1:1emulsion with Nujol to the equivalents of sodium chloride needed to break the emulsion was taken. This is a modification of the test used by Parsons and Wilson.2 Twenty-five cubic centimeters of Nujol were emulsified by two intermittent stirrings of 30 seconds each, with 10 cc. of N / 3 0 sodium oleate solution; the interval of rest between stirrings was likewise 30 seconds. Water and N / 2 sodium chloride solution were then added in quantities to make the final volume of aqueous phase 25 cc. Upon repetition of the intermittent stirring, if the emulsion separated into two equal layers within 30 seconds after stirring ceased, it was considered broken; if it was not, a fresh emulsion was made up and more sodium chloride and less water were added for the second trial. Thus the only variables were time and rtbsolute salt concentration.
OF TECHNOLOGY, C A Y B R I D G E ,
MASS
reproduced, the effects of admitting carbon dioxide, oxygen, increasing the temperature, and making up the solution in the presence of three times as much air as before, were determined. The comparative curves are shown in Figure 1. Absolute checks for the maximum and minimum values in Curve 1 were obtained from six N/30 sodium oleate solutions. From these results it was evident that when all factors except the absolute concentration of salt used to break the emulsion were kept constant, the resistance of its emulsions to salting out, and in that sense the emulsifying power of sodium oleate, fluctuated with age. The temperature at which the solutions were aged and the amount of carbon dioxide which came in contact with them had considerable effect on the degree of aging; oxygen had less effect. Lather Tests
In lather tests the usual procedure is to place the soap in "hot" water, degrees unspecified, heat till solution is effected, cool to room temperature, make up to volume, and shake a sample under standard conditions. Under such circumstances it might be expected that the effect of age would be manifest to considerable degree. For the present tests two series of solutions were used. In the first series a solution was made up by the ordinary process as outlined above. The choice of concentrations was narrowed to 0.1-0.2 per cent (dry basis), below 0.1 per cent the small volume of lather allowed too large a percentage of experimental error, while above 0.2 per cent the volume of lather was too large for the tubes and the solutions Factors Affecting Aging jelled quickly at room temperature. For the second series It was soon evident that temperature control and exclusion the soap was placed in water a t 85" C., using the same volume of carbon dioxide and oxygen were necessary to secure re- each time, maintained a t that temperature for 20 minutes, producible results. Accordingly, the soap was aged in a cooled to 25" C., and made up to volume. Exposure to air thermostat a t 25" C., withdrawn from its flask through a was minimized during this period, and the pbrtions of solution siphon arrangement fitted with soda-lime and pyrogallol- tested were siphoned off with the usual scrubbers, pyrogallol scrubbers, and made up in boiled distilled water with the and soda lime. In order to get the comparisons on a defisame volume of air present above the solution each time. nite basis, the first tests on both series were made half an Making the solutions up in a flask that had been scrubbed hour from the time the sample was placed in the water. out with nitrogen gave low results which could not be checked, One hundred cubic centimeters of solution were shaken so the attempt was abandoned. one minute in a lathering tube and the volume of lather was When this method yielded results which could be repeatedly read off half a minute later. Curves showing the characteristic difference between the 1 Received July 18, 1925. two series are given in Figure 2 . A 0.2 per cent solution of )THISJOURNAL, 13, 1116 (1921).
