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THE INDIA RUBBER WORLD 



[August i, 1904. 



MANUFACTURE OF FRUIT JAR RINGS. 



BY J. \V. C. 



THE production of fruit jar rings has assumed such propor- 

 tions as to make it an important branch of the rubber 

 industry. Methods of production and packing of the goods 

 made have, in the presence of ever growing competition among 

 manufacturers, undergone great improvement within the past 

 few years. 



A jar ring is not difficult to make, but, like every other thing 

 in the rubber line, it has to be made "just so." The com- 

 pounded stock is generally run through the tubing machine to 

 a slightly larger outside diameter than is required, it being 

 necessary to offset the reduction in size that results when the 

 material is wrapped for curing. As the stock is run from the 

 tubing machine in the form of a cylinder or tube, it is cut off 

 in lengths of, say, 30 inches. These are immediately placed 

 upon iron or steel tubes 8 or 10 inches longer than the length 

 of stock. The outside diameter of the steel tube being that of 

 the inside diameter of the intended jar ring, the cylinder of 

 stock is tightly bound to the steel tube by means of wet cloths. 

 The workman first places a ring or washer on either end of 

 the tube and against the ends of the cylinder of gum, to pre- 

 vent its lengthening under pressure. These washers are held 

 in place by means of a sheet of muslin called a "jacket," which 

 is spread on by hand while wet, completely covering the cylin- 

 der and going 1% times around it. To accomplish this suc- 

 cessfully the tube is placed horizontally upon a table and ad- 

 justed to small rollers or wheels at either end, which are made 

 to revolve at a high rate of speed. Upon this "jacket " is then 

 smoothly wound a strip of muslin long enough to make two 

 thicknesses of wrappings. This is also applied wet, the work- 

 man exerting his strength so that the wrapper be tight as well 

 as smooth. The cylinder is then ready for vulcanizing. 



A tubing machine running a jar ring stock, should turn out 

 from 5000 to 6000 pounds in ten hours. To produce and handle 

 this quantity will require the laqor of three men at the tubing 

 machine and four men at jacketing and wrapping. Six thou- 

 sand pounds of an average weight white Mason jar ring, and 

 5000 pounds black, represent a fair day's work, and would 

 make, approximately, 1000 tubes. 



The cylinders as above prepared are placed on the carriage 

 of an open steam vulcanizer, and receive a cure of 30 minutes 

 at 50 pounds pressure, more or less, according to requirements. 

 Wrappers and jackets are quickly removed and the cured cyl- 

 inder is ready for the cutting machines. There are several 

 styles of these machines, but the principle in all is the same: 

 To slice or cut the gum cylinder into jar rings of a specified 

 thickness, at a high rate of speed. Compressed air, admitted 

 to the interior of the cylinder, expands it sufficiently to admit 

 of its beingquickly thrust upon a mandrel. This mandrel isad- 

 justed to the cutting machine, where it is made to revolve rap- 

 idly. The cutting is done by a sharpened steel blade securely 

 fastened to a traveling carriage and which receives its cutting 

 stroke from a cam. Such a machine will cut from 350 to 500 

 pounds in ten hours. Workmen should be charged with value 

 of rings spoiled by a dull or wrongly adjusted cutting blade, or 

 other neglect. Waste from cutting and imperfections in stock 

 should not exceed an average of 2 per cent. 



The cut rings are stripped from mandrels, compressed air or 

 some simple form of machine being used. These rings are 

 spread upon tables where they are inspected, counted, tied in 

 bunches, and packed. Rings are counted out in lots of a dozen, 

 which is a convenient form for tying in bunches, or placing 

 loose in fancy boxes holding a dozen rings or in cartons holding 



1 gross. Large canneries and other concerns order jar rings 

 shipped in bulk in barrels for their particular use, but the public 

 has become fastidious and must now have a smooth, shapsly 

 ring, of a certain color, and packed in a handsome box. All 

 jar rings are not run on the tubing machine, the expensive fine 

 red rings being built up into cylinders by means of the hand 

 roller. The cutting also is more successfully done by hand on 

 slow speed lathes, rather than by the automatic machines. 



An important item in the successful cutting of jar rings is 

 the cover for the mandrels. These mandrels are made of brass 

 tubing, which must be covered with some suitable material 

 into which the point of the cutting blade may strike when it 

 passes through the gum cylinder, without injury to the knife 

 or the rings cut. This covering is generally of a cheap grade 

 of compound, and it is the practice in some factories to hand 

 roll it onto the mandrel, and then wrap and cure in the usual 

 way, after which it is dressed down to size on a hand lathe. A 

 good deal of this process, besides being expensive, is unneces- 

 sary. The layer of stock on a mandrel becomes so badly cut 

 up in two or three days' use on a ring cutting machine as to 

 render the recovering of the mandrel a necessity. Cover it 

 with a good tough stock, sheeted very thin on calender, and 

 built up to exact diameter required by means of hand roller. 

 The mandrel is then ready for use. The uncured stock will 

 stand more punishment than when cured, and when worn out 

 can be stripped from the mandrel, sent to mill room, softened, 

 again sheeted on calender, and used on mandrels again and 

 again. 



By the first named method the labor cost is much greater, 

 and the loss in cured stock fully 90 per cent. By the second 

 method about 90 per cent, of the stock is saved for continued 

 use. I know of one large factory that saved $100 per month 

 by this change in methods. Some factories experience trouble, 

 in that stock used for white jar rings comes " blowed " or full 

 of small pores. Its possible cause is moisture still remaining 

 in some of the compounded ingredients. This can be over- 

 come by "scalding" — i.e., working the stock over for 30 

 minutes or more on a very hot mill. 



The vacuum jar ring differs from the flat jar ring in that it is 

 run from the tubing machine in the form of a small, round 

 cord. An expensive stock of a light red color is generally 

 used. The work on the tubing machine requires great care 

 and skill to keep the cord to an exact gage. It is therefore 

 frequently weighed and calipered during this operation. As 

 fast as run from the machine it is wound on zinc covered 

 drums, and until the surface of the drum is covered with one 

 layer. A diagonal cut is then made through this layer, per- 

 mitting of its being spread upon a tray. At the work table it 

 is again cut, this time into lengths corresponding to the diame- 

 ter of the rings to be made. The diagonal cut is preferable, as 

 it admits of each piece being formed into a ring with a splice 

 joint. The work of splicing is done by hand, girls being em- 

 ployed. It requires great skill to handle the stock without 

 stretching and do splicing neatly. Large covered pans are used 

 in curing, the rings being covered with talc. A bath in glycer- 

 ine brings out the bright color of the stock. Tied in bunches 

 of 1 gross, the rings are then ready for shipment. 



Rubber goods in Australia. — A correspondent of the 

 Ironmonger, the representative British hardware journal, re- 

 ports on the origin of the stocks of hardware found in a leading 

 store in Melbourne, Australia, his letter including the following 

 items: Wringers, with India-rubber rollers, American makes ; 

 India-rubber hose pipes, North British Rubber Co., Limited, 

 and some American cotton covered. 



