July 1, 1911.] 



THE INDIA RUBBER WORLD 



375 



REFORMING RUBBER; THE NEW PROCESSES. 



BY JOSEPH T. WICKS. 



/"CONSIDERING these new processes of treating rubber waste: 

 ^^ remanufacturing old rubber cab tires, wornout valves and 

 cuttings of cured sheet, making the same into cylindrical buffers 

 and other new moulded goods, for the market, by the process 

 known as reforming rubber, the reforming process is, in our 

 opinion, certainly not an improvement. 



The thing that first strikes us is that none of the men engaged 

 therein are india-rubber men. Neither, as a rule, do they employ 

 rubber men. Ask the managers what they have been ; a civil 

 engineer conducts one factory; a manufacturing chemist of drugs 

 and chemical manures heads another reforming rubber works. 

 It is the same with the workers ; they are drapers' assistants, 

 engineers, travelers, with a sprinkling of rubber workers. 



We fail to see how such heterogenous help can hope to make 

 a success of a new industry. One would think that men who 

 know what has been done in the manufacture during the past 

 sixty years ought rather be employed ; no, it seems to be a case 

 of "Fools rush in where angels fear to tread." 



It is our practical and expert opinion that this reforming, as 

 now conducted, cannot be made to pay; it is not a commercial 

 process; the whole thing is amateurish and would not be tolerated 

 by experienced rubber men. 



We consider that the cost of the expensive .steel molds used 

 in this reforming process is absolutely prohibitive. To prove 

 this assertion we will make some comparative tests. 



The rubber powder, or, as it is usually called, rubber crumb, 

 is prepared from good quahty cab tires. Old cab tires are ground 

 on a powerful two-roll grinder, reduced to fine crumb ; the crumb 

 is dried in an oven, and as wanted taken out of the oven in a 

 warm state, sprinkled lightly with petrol, and is then ready to 

 be placed in the steel moulds for pressing into the shape of the 

 required article. 



For instance, to make an air-pump valve for a steamship. In 

 the ordinary way we take a turned steel ring, six inches 

 diameter by one-half inch thick. Then we take a piece of com- 

 pounded rubber sheet and roughly trim it to the size of the steel 

 ring and place the rubber valve therein ; the valve is now ready 

 for pressing and curing. This process of making a valve for a 

 ship's pump is extremely simple and inexpensive. 



Now by the new reforming process, instead of this simplicity 

 the process is complicated and expensive. 



We use the steel valve ring, but as the rubber is in the state 

 of "crumb," being light and bulky, to get this crumb into the ring 

 a second or outer ring is required as a container of the crumb. 

 To make a valve one-half inch thick requires about lyi inches 

 of bulky crumb. Then you need a plunger to force and press 

 the crumb into the original valve ring. So that in place of one 

 ring, by the new process two rings and a powerful plunger are 

 required. The manufacture will not stand the cost of these 

 expensive additional tools. Consider the dozens of various sizes 

 of valves, all requiring tools. 



Such a valve made by the reforming process is cured for about 

 ten minutes at 160 pounds steam pressure. Here, again, is 

 another fault ; as rubber is a vegetable material it will not stand 

 160 pounds steam pressure. 



We know of a ship's engineer who was induced to put these 

 rubber crumb valves into his pumps. He could not get his ship 

 out of the West India Docks. London, before the valves broke 

 into pieces. That engineer was lost as a customer for reformed 

 rubber. 



This valve failure means that the material of which the air 

 pump valves were made was not homogeneous, there being insuf- 

 ficient cohesion between the particles of crumb. 



The same will apply in making round buffers for railway 

 trucks. .\ buffer two inches thick will require, say, five inches 



of crumb, to be pressed down to two inches; hence additional 

 tools to do the job by the new process. 



The reforming process is, moreover, very wasteful. For in- 

 stance, in moulding shoe-heel pads from steel plates 10 inches 

 square, six of the small plates on a larger plate, making 30 by 

 30 inches. Suppose the pads are S/16 inch thick ; to mould them 

 from crumb free from faults, the crumb is spread over the moulds 

 to the depth of nearly one inch. When pressed and cured there 

 is a complete sheet, giving 1/32 inch, or even more, thickness 

 of waste, besides the extra thickness of each of the numerous 

 pads. 



These heel pads are cured for about eight minutes at 160 

 pounds steam pressure. On account of excessive heat many 

 of these pads are "crusty" in a few weeks. 



The hydraulic presses are enormously powerful, giving 1,000 

 pounds per inch on the ram, for this light work of heel pad 

 moulding. 



Therefore nothing but steel moulds can be used under these 

 presses. It is well known that by the ordinary method there is 

 little or no waste in making heel pads. The disadvantages in 

 the new process are : 



( 1 ) Machiiury required is excessively powerful and too 

 expensive. 



(2) Costly and additional moulds. 



(3) Wasteful method, there being too much waste as cured 

 trimmings. 



(4) Goods imperfect and liable to perish. 



(5) Manufacture does not pay; no profits have been earned up 

 to date. 



One London company's shares, $5 when first issued, rose to 

 $20, but have now fallen to much under $5. 



The new men engaged in this new industry should adopt the 

 ordinary methods of manufacturing moulded rubber article^. 

 L'nless this change is made, and the new factories run on a com- 

 mercial basis, we shall in tvio or three years' time look in vain 

 for the present firms, as excessixe running expenses will destroy 

 them. It is folly to attempt the manufacture of rubber goods 

 without the aid of skilled mill managers and trained workmen. 



THE SHORE SCLEROSCOPE. 



THE invention of Albert F. Shore, this simple but ingenious 

 little instrument offered the first reliable means of making 

 a quick and accurate test of the hardness of metals. Its opera- 

 tion is based on hardness or resist- 

 ance to penetration, offered by the 

 metal or other material, as recorded 

 by the height to which a small 

 plunger hammer equipped with a 

 peculiarly shaped point, will rebound, 

 after being dropped on to its surface. 

 It is obvious that the harder the ma- 

 terial, the sharper the rebound will 

 be, a soft or comparatively non- 

 resistant substance tending to absorb 

 the shock of the impact. A scale 

 registers the extent of the rebound 

 and affords an accurate idea of the 

 hardness of the material under test. 

 In the details of its construction, to 

 allow of its use in conducting dif- 

 ferent tests, the instrument displays 

 more than ordinary mechanical in- 

 genuity, the elevation and release of 

 the plunger hammer being effected by 

 means of rubber bulbs. [The Shore 

 Instrument Manufacturing Co., New 

 The Shore Scllroscope. '^'ork, X. Y.I 



