May 1, 1921 



THE INDIA RUBBER WORLD 



557 



to the vulcanizing temperature. It is said that a vulcanizing tem- 

 perature much lower than that ordinarily used can be employed 

 satisfactorily vvith this process. The fusible metals employed 

 are in the form of an alloy, commonly lead, tin, and bismuth, 

 to which antimony or cadmium is sometimes added. One of 

 these alloys, known in chemistry as Lipowitz', is composed of 

 bismuth 50, lead 27, tin 13, and cadmium 10 per cent, and it melts 

 at 140 degrees F. 



The various metallic combinations are remarkable for the 

 pressure they can withstand, for breaking with a clean fracture, 

 for their hardness, and the sharpness of their castings. 



The first impression of those who have not tried molding rub- 

 ber in fusible metals is that the alloys liquefied by heat would 

 burn the rubber, but this fear is dispelled when celluloid does 

 not ignite when imbedded in the molten mass or when one's 

 fingers are thrust into the hot flowing metal without injury. The 

 metals may be used indefinitely, the first cost being the only one. 



Dr. Stone is now giving his attention to the mechanical aids 

 required in vulcanizing by the new process, such as the troughs 

 or containers for the curing metals, pressure and temperature- 

 controlling devices, electric heating arrangements, etc. He also 

 states that he has perfected a process for making seamless inner 

 tubes with the fusible metals. 



fjgj 



FJg.3 



Stone Fu.'^ibi.e Met.m. Mold 



Referring to the accompanying illustration of Stone's method. 

 Fig. 1 shows a container with a rubber heel and eraser in posi- 

 tion, and the method of pouring the molten metal. Fig. 2 is a 

 cross-section of the container with the rubber articles embedded 

 in metal. 



.■\ny low fusible substance may be emploj'ed, preferably one 

 composed of two or more metals intimately united, the ratio of 

 the composition varying in accordance with the degree of heat 

 at which fusibility is desired. The rubber heel 6 or the eraser 7 

 are preferably preformed and placed in a container 8, the metal 

 5 is subject to heat and liquefied, whereupon it is poured over and 

 around the articles, as shown in Fig. 1. The metal is then al- 

 lowed to solidify and the articles are firmly embedded in solid 

 metal. The heat is next applied and the metal is kept at the 

 vulcanizing temperature for the time required. The metal is then 

 allowed to cool, when it is liquefied and drawn off. 



It is difficult for one familiar with the rubber business to 

 evolve anything wholly new, and it is almost impossible for 

 others to do so. Dr. Stone is doubtless perfectly sincere, and in 

 calling fresh attention to fusible metals in rubber molding he 

 may have done the industry good, but to us the novelty is not 

 apparent. Take for example the Glcason patents for fusible 

 cores for water bottles, inner tubes, etc. 



CLEASON'S FUSIBLE CORE MOLD 



Gleason's water-bottle mold cmi)lnys a rigid mandrel or core 

 of soft metal which melts at a temperature below that destructive 

 to rubber. Diiring vulcanization the inner wall of the water 

 bottle is sustained, first by the fusible core and when that melts, 

 by compressed air or gas. The illustration shows a plan view of 

 the lower half of the mold, a cross-section of the mold, and the 

 complete bottle. 



The bottle is formed by assembling the two main pieces A, the 



edging B, the tail piece C, neck D, and collar E. F is a tube 

 connecting the valve G with the interior of the water bottle. 

 The fusible core H is a narrow, open band, which conforms in 

 shape and thickness to the interior of the unvulcanized bottle. 

 The core is connected with a non-fusible piece /, which consti- 



Gle.\son's Mold and Complete Water Bottle 



tutes the nipple of the finished bottle and becomes attached to 

 the rubber during vulcanization. It is also connected to the 

 non-fusible part /, which forms the funnel of the bottle. 



When the various parts are assembled in the mold and the 

 core is in place, the mold is clamped together and heated to 230— 

 285 degrees F. Vulcanization proceeds inward from the ex- 

 terior. The fusible core melts before the bottle is entirely cured, 

 and the molten metal is drawn out through the tube F. The 

 oottle may be expanded during the final stage of curing, by com- 

 pressed air or by gas from a volatile liquid introduced through 

 the tube F. 



THE EATIN PROCESS 



Fusible cores are, to be sure, not what Dr. Stone claims, so 

 we cite for his attention the Eatin British patent No. 2637, issued 

 November 21, 1859, for curing india rubber compound. Briefly 

 it is thus explained. "The process consists in the use of a 

 metallic bath for the purposes of vulcanization, so constituted 

 as to fuse at or below the lowest degree of temperature re- 

 quired in vulcanization and capable of being elevated readily to 

 the highest temperature required in the process. The prepara- 

 tions of india rubber and sulphur immersed in such a bath when 

 at its fusing point are thoroughly vulcanized in from two to five 

 hours, according to the temperature maintained. 



"The composition of this bath may be varied to meet any re- 

 quired case. It will be well usually to make use of an alloy, 50 

 parts of bismuth, 31 of lead, and 19 of tin, fusing at about 203 

 degrees F. When the articles will bear a higher temperature 

 than 212 degrees F. in the early stage of the process a bath of 

 higher fusing point may be used by increasing the proportion 

 of tin and lead and by the addition of zinc or other metal " 



MOTOR TRUCKS IN THE TEXTILE INDUSTRY 



Reports received from 414 textile mills located in various parts 

 of the country show that approximately half of the firms use 

 motor trucks. Of this number 153 actually owned trucks, while 

 about 20 per cent more have their trucking done on contract. 

 Reports indicate there is more work for light trucks of less than 

 IJ^-ton capacity, and that more than 60 per cent of the trucks are 

 three tons or less. Relating to the tire equipment, there were 140 

 reports; 117, or 84.5 per cent, were using solid tires while the 

 other 23, or 16.5 per cent, reported pneumatics in use. 



