THE INDIA RUBBER WORLD 



[January 1, 1919. 



Vulcanization Control. 



THE interest of every practical rubber worker centers in 

 the process of vulcanization because it is the basic opera- 

 tion on which the value of his output depends. Vulcani- 

 zation, or the chemical union of sulphur and rubber as made 

 known by Goodyear, Hancock and Parkes in the last century, 

 came under scientific control only within recent years. 



The work of the heater-man in charge of the operation of the 

 vulcanizer formerly constituted a very imperfect means of con- 

 trol. The human operator cannot be relied upon, no matter 

 how skilled and conscientious, just because he is human. He 

 forgets, becomes fatigued, has his attention distracted and 

 makes mistakes. It is unnecessary to emphasize the importance 

 of exact control of any manufacturing process, because it is, in 

 fact, a.xiomatic. Without control uniformity of product is im- 

 possible. 

 IMPORTANCE OF UNIFORM TEMPERATURE AND DRY STEAM. 



Mention may be made of certain points which emphasize the 

 value of vulcanization control in eliminating defective product. 

 The effect of too long continuation of the heat of vulcanization 

 is "overcured" or "burned" product resulting in such defects as 

 excess hardness, lack of elasticity and rapid deterioration with 

 age. Too short continuation of the cure leaves the goods 

 "undercured," soft, tacky, or porous, and practically without 

 elastic efifect. 



Curing in wet steam is undesirable because it results in un- 

 even distribution of heat in the goods, hence irregularity of cure 

 and tendency to undercure. Dry steam circulation in the heater 

 and constant elimination of condensation are essential to uni- 

 form heat distribution, either in a boiler or press cure vulcani- 

 zation. 

 THE NECESSITY OF GRADUAL INCREASE IN TEMPERATURE. 



It is always desirable in vulcanizing rubber goods in large 

 masses, as, for example, thousands of feet of hose on poles or 

 solid tires in molds, to raise the heat gradually over a given 

 period to allow for heating the hose poles or molds to the point 

 where they will not cause loss of heat by condensation, and thus 

 allow the rubber to attain the vulcanizing temperature of the 

 steam. Sometimes this result is obtained by raising the tem- 

 perature of the heater gradually and sometimes by raising it in 

 a series of steps. The object is to ensure the application of the 

 vulcanization temperature to the goods for a prescribed length 

 of time. 



Having determined a suitable plan of conducting the heat 

 progressively, these conditions may be positively reproduced at 

 will by mechanical means. By hand-regulation the rise of heat 

 from stage to stage lacks uniformity and the vulcanizing tem- 

 perature never remains constant, but fluctuates seriously. 



These irregularities have a marked influence on the perfection 

 and uniformity of cure and frequently are the cause of perplex- 

 ing freak conditions very baffling to eliminate. 



AUTOMATIC CONTROL OF VULCANIZATION. 



The introduction of automic control of time, temperature and 

 exhaust has made possible perfect vulcanization, a condition 

 vitally essential to a guaranteed product. The development of 

 automatic control of vulcanization has been perfected and ex- 

 tensively adopted in American practice. The system necessi- 

 tates special instruments and system of piping, but is not subject 

 to disarrangement and is positive and reliable in operation. 

 STEAM CONTROL. 



The principle on which steam control is regulated is the trans- 

 mission and multiplication of the motion of a capsular spring 

 which expands and contracts with changes in temperature and 



consequent change in steam pressure. A ball valve is thus 

 operated, which allows more or less air pressure to open or 

 close a diaphragm-motor steam valve to a greater or less extent. 

 Compressed air affords an instant, flexible and effective means 

 for doing any amount of work required, especially when the 

 steam temperature shows only a slight tendency to change, and 

 when, therefore, the capsular spring moves only an infinitesimal 

 extent. 



For the operation of a tire-vulcanizing press a compound 

 controller is frequently used. One of these controllers main- 

 tains a uniform steam temperature within the press, while the 

 other takes care of the exhaust at the bottom of the press by 

 periodically relieving the heater of the water of condensation 

 and the super-saturated steam. An automatic time control in- 

 strument is set to regulate progressive increase of temperature 

 and the duration of the cure, at which point it promptly shuts off 

 the steam supply and opens the exhaust. It can also be arranged 

 to turn on cold water for flooding and cooling the contents of the 

 vulcanizer. 



CHARTING THE CURE. 

 In the system of vulcanization control is usually included a 

 recording thermometer which produces on a chart a graphic 

 record of just what the controllers have accomplished in main- 

 taining uniform temperature and time and serves as a perma- 

 nent record. Examination of the charted records shows the 

 perfect exactness with which it is possible to control the time 

 and heat of the vulcanizing operation. 



OPPORTUNITIES FOR SOUTH AMERICAN TRADE. 



John B. Maus, export manager of The Fisk Rubber Co., 

 Chicopee Falls, Massachusetts, whose portrait appeared in our 

 issue of September 1, 1918, has just returned from a lS,00O-mile 

 trip through South .'\merica. On the evening of December 17, 

 1918, he addressed the Chamber of Commerce, Springfield, 

 Massachusetts, on the various aspects of trade in the future 

 with South America. About lOO were present at the meeting. 



Mr. Maus emphasized the following needs for successful 

 commercial relations v/ith our sister republics : concentration 

 on the South American market; learning to know the South 

 American people ; adequate knowledge of the Spanish language ; 

 comprehensive knowledge of geography and familiarity with 

 the financial and business relations of the world ; the sending 

 of trained men to South America to study credits and com- 

 petition ; the arrangement by our banks to extend loans to 

 South Americans and establish branches in their country. 



Incidentally, Mr. Maus cited the fact that in 1913 British ships 

 cleared the Argentine with 1,843,328 tons of merchandise, while 

 ships flying the American flag cleared only 27,190 tons. He 

 advocated a great merchant marine composed of fast vessels 

 manned by crews under merchantmen's pay, to be picked from 

 our Navy. 



THE RUBBER MARKET AT SINGAPORE. 

 There seems to be considerable doubt as to the eflfect on 

 the price of rubber by the present weekly Singapore auction 

 sales, which last two days. On the other four days there are 

 private sales between parties meeting in each other's offices. 

 There seems to be a general feeling in favor of the establish- 

 ment of a rubber exchange, in which sellers could exhibit 

 their samples, and where buyers and sellers could meet for 

 about two hours every morning. The exchange would, at 

 first, only supplement the weekly auctions. 



