418 



THE INDIA RUBBER WORLD 



BALATA BELTING: ITS MANUFACTURE AND USE. 



By Hancock Ilaskiits. 



THAT Ijalata belling is better than rubber, leather, or even cot- 

 ton belting for every purpose is not true. W here water, acid, 

 or acid fumes are present, it is, however, better than any other. 

 It will not stand high heat, but on the other hand, the moderate 

 heat developed by running a balata belt softens the gum a little 

 and brings it to the surface, thus renewing the belt cover for a 

 long time. It should never be used in rooms that are over 100 

 degrees in temperature, nor is it advisable to use it where it is 

 constantly exposed to steam. 



Properly made balata belting is possessed of great tensile 

 strength and its pulling power is wonderful. It clings to the 

 puUey better than any other material and needs no belt dressing. 

 It also has the added advantage of running true. Furthermore 

 no helt fasteners are needed in splicing. In making a joint the 

 enQj- are simply heated until they become loose and sticky. The 

 splice is then made on an angle of 45 degrees, stepped in about 

 one inch to each ply, pressed down hard and ironed. When 

 cooled it is as strong at that point as at any other. 



The use of balata belting is very large for conveying purposes 

 in mines, but especially in acid works, dye houses, bleacheries, 

 ammonia works, slaughter houses, tanneries, breweries, and also 

 in shoe and hat factories, and in special chemical industries. 



The preparation of balata for belt manufacture is very simple. 

 Rubber manufacturers who are not equipped for handling plastics 

 like gutta percha and' balata often do the cleaning and massing 

 on ordinary washers and mixers. The better way, however, is 

 to have a cutter (a circular knife is excellent) that cuts the raw 

 blocks or sheets into strips and pieces that are more easily 

 handled. This is done dry and cold and is much like cutting 

 leather or rawhide. The resulting strips are then shredded by a 

 variety of tearing machfnes. A common one is a spiked drum, 

 revolving in a trough. The shredded mass is next thrown into 

 a tub of cold water and agitated. The heavy adulterants, if 

 there are any, sink to the bottom, while the shredded gum 

 particles float. The partially cleansed shreds are put into a 

 tub of hot water where with a little manipulation they unite 

 into a plastic mass. This can be used just as soon as the water 

 is expressed. 



For the best work, however, the gum should be put into a 

 closed washer or a masticator-washer and thoroughly washed 

 in hot water into which steam is forced. The remaining impuri- 

 ties are thus freed and either sink to the bottom or are forced 

 out through apertures in the inner walls of the washer. The 



this is niit absolutely necessary in belt making, but some manu- 

 facturers insist that it gives a better product. 



So far, the handling of balata is practically the same as of 

 gutta percha. It should I)e noted, however, that balata is softer 

 than gutta percha and, furthermore, that it is not so easily at- 



cleaned mass is then put on heated rolls that express much of 

 the water. If a thoroughly dense homogeneous mass is re- 

 quired, the almost dried gum is forced through a press-strainer 

 containing a battery of sieves, each of different mesh. This re- 

 moves the remainder of the water and all air bubbles. Of course, 



Fig. 2. Belt-Stuking M.\chine. 



tacked by the air. It also cools much more slowly so that, once 

 heated, it can be handled and made up more easily. These facts 

 and the further one that the crude gum is often very clean, al- 

 low of its being simply treated in hot water, in a tub washer, 

 and dried on ordinary mixing rolls. The product is not as 

 smooth as gutta percha. but is more elastic and adhesive. 



In this connection details of balata belt-making as practiced 

 in a European factory are very interesting. The crude balata 

 is first wa.shed in machines that are very similar to those em- 

 ployed for washing crude rubber. They are, however, of con- 

 siderably lighter construction, having smooth rolls instead of 

 corrugated. These rolls revolve at different speeds to tear the 

 balata while it is washed in order to effect as thorough a clean- 

 ing as possible. The balata sheets, after diying, are put into 

 a slightly warmed, jacketed mixing machine, and with the addi- 

 tion of benzine, and by constant stirring, are reduced to a solu- 

 tion. .\s soon as a thorough mi.xture has been obtained, the 

 thick compound is transferred to a jacketed solution trough, 

 which is fixed above a spreading machine. In this trough, 

 which is heated, the mass is raised to a temperature that makes 

 is sufficiently plastic to permit spreading. 



The solution trough has a capacity of 40 gallons and can be 

 closed in order to keep out dust. The belting fabric is wound 

 on a roller provided with a brake and passes over another 

 roller, under the solution trough, between a roller and the 

 spreader knife. While the cloth unrolls, the balata solution is 

 distributed over the cloth surface in front of the knife, through 

 three cocks that are equidistant throughout the length of the 

 solution trough. 



The cloth absorbs the solution as it is spread by the knife 

 or "doctor," which can be adjusted to regulate the thickness of 

 (he solution. The treated fabric then passes over other rollers 

 and is led to a winding apparatus. To wind up the spread cloth, 

 a windlass-rack is fitted to hold short lengths of pipe in its arms. 

 These short pipes are fed as fast as the cloth advances, and 

 this means the sticky fabric is kept from adhering to itself 

 as it is wound up, the windlass holding up to 600 feet of impreg- 

 nated cloth, which is thus air-dried. 



The fabric is spread thick on one side and thin on the other 

 and is then transferred to a grooving and cutting machine, to be 

 trimmed and cut to the required length and width. The ma- 

 terial is wound on a roller which has a brake, and from this it 



