14 



THE INDIA RUBBER WORLD 



[October 1, 1920. 



and the market was soon in a strongly competitive condition and 

 flooded with rubber heels made after the new ideas. 

 NAIUNG MACHINES PROVE SUCCESSFUL 



There were a number of enterprising shoe manufacturers who 

 at once installed these nailing attachments for their regular heel- 

 ing machines and tried out the new process. It was soon dem- 

 onstrated that the greater driving and clinching force of the 

 machine driver aggravated the defects in the flat-backed heels and 

 that whereas some manufacturers had continued to use them by 

 adopting careful hand nailing methods, they were now impos- 

 sible. Those who had not already changed their molds in this 

 respect found that it was necessary to do so and so they remade 

 their back plates so as to give the heel a slight concavity. The 

 real aim, of course, was to give the heel enough concavity to 

 make it offset the spring at the edge. 



Hardly had this been done before an avalanche of reports poured 

 in that the rubber heel nail-holes did not fit the driving fingers 

 of the driving head. Careful measurements and comparisons were 

 made with the key template and mold but no variations appeared. 

 It was evident that the mold makers had done their work well, 

 for almost no variation was found in thousands of cavities, but 

 all had overlooked the fact that when the rubber heel was re- 

 moved from the molds while hot, it shrunk when cool. This 

 shrinkage varied with different compounds but it was found to be 

 sufficient in most cases to pull the nail-holes out of line although 

 the molds had originally conformed with the template measure- 

 ments. 



TROUBLESOME WASHERS 



It must be understood that a modern shoe factory is a most 

 sensitive organization and a single rack of shoes that does not 

 proceed in its orderly and regular manner through the various 

 rooms may cause no end of trouble and actual productive loss. 

 The machine operations are so swift that a single heel jamming 

 in a nailing machine may easily tie up a macjiine for a number 

 of hours. Or the shoe itself may be spoiled, causing a loss quite 

 out of proportion with the loss of the heel itself. This misaline- 

 ment of nail-holes called for quick action on both sides and it 

 was soon discovered that the only way to remedy this defect was 

 to correctly determine the amount of shrinkage in a given stock 

 and allow that much variation when placing the nail-hole posts or 

 studs in the molds. A wide range of heel stocks had been the 

 fashion, but this discovery resulted in cutting down the number 

 of different compounds considerably and rubber manufacturers 

 who had been making their compounds in a more or less hit-or- 

 miss fashion out of every available kind of scrap now came to 

 realize the desirability of standardization in compound as far as 

 possible. The matter of stock shrinkage now became another 

 definite factor to be reckoned with when compounding heel stocks, 

 as also did the different properties of black, tan and white com- 

 pounds. Some of these compound problems might have been very 

 much more difficult had if not been for the invention of the conical 

 washer or burr. 



THE CONICAL WASHER INTRODUCED 



Undoubtedly, the success of the machine nailing process for 

 rubber heels would have I)een considcraibly delayed had it not been 

 for the introduction of the conical washer. It was found that 

 with the flat washer, a very slight variation was sufficient to jam 

 the heel in the machine, and even though the driving fingers were 

 purposely made of long springy steel wire construction to adjust 

 themselves slightly to inequalities in the positions of the nail holes 

 they very often did not function properly if the nail holes were 

 the least bit out of line. On the contrary, it was found that with 

 the conical washer some inequalities might exist and still fail to 

 interrupt the successful operation of the nailing machine. The 

 theory of this conical washer was that its sloping sides served as 

 a guide for the driving fingers and that by taking advantage of 

 the spring in these driving fingers, the conical washers permitted 

 the nailing of heels which would be impossible were they con- 

 structed with flat washers. This theory proved entirely sound in 



practice and the conical washers were soon adopted as standard 

 by the leading manufacturers of rubber heels. 



Production was somewhat disturbed by the discovery that while 

 an operator might rapidly place the flat washers on the studs or 

 washer pins without any particular care or attention, the same 

 operator must proceed much more slowly if he were to apply 

 conical washers, as they all had to be applied right side up. A 

 single conical washer inverted meant the undoing of all that had 

 been done in a constructive way, as it made a heap of trouble in 

 the shoe factory even though it was not discoverable after the 

 heels were molded. This operation of molding heels was mostly 

 a piece-work operation and the price scale was necessarily ad- 

 justed to suit the new requirements. In spite of the increased 

 wage schedule, the production figures were lower and in some 

 places the work was handled by two men working together, or a 

 man and a girl. The one applied the washers to the washer-pins 

 and dusted the molds, and the other handled the presses and re- 

 moved the contents ready for the refill. This plan resulted in 

 more contented workers but did not bring the production figures 

 back to where they were under the flat washer plan. 



Some idea of the number of washers handled in a single day 

 may be gained from the following. A single workman often han- 

 dled five presses, molding twenty heats a day on each, and carry- 

 ing three 20-cavity molds to each heat for each press. Theoret- 

 ically, this meant a grand total of 3,000 pairs of heels per day 

 for one man and a total of 30,000 washers to be placed right side 

 up with care, counting five washers to a heel. Some accuracy 

 was required to have every one of them properly placed. There 

 were those who thought to divide their production by using coni- 

 cal washers on heels for the shoe manufacturing trade and flat 

 washers for the shoe repair trade. This was possible but hardly 

 practical, as the slightest mix-up meant an endless amount of 

 trouble. If the wrong kind should happen to get to the machine 

 nailer, a tie-up might result that would cost many dollars in lost 

 production. Thus it remained pretty near standard practice that 

 conical washers should be molded into all standard heels. There 

 are those who still believe that the flat washers can be satisfac- 

 torily used with the machine nailing attachments, but they are in 

 the minority and their product suffers by comparison on this point, 

 if in no other, when viewed by a cautious and far-seeing purchas- 

 ing agent. Even if the purchasing agent should procure heels 

 with flat washers, there are few heeling machine operators who 

 would take chances to tie up their day's earnings at piece-work 

 rates by using the flat washers, and you will see many an 

 operator starting to use a new heel for the day's run cut one open 

 with a knife in order to ascertain what style wa.sher has been 

 used. 



HIGHER COST LEATHER FAVORS RUBBER HEEL SALES 



While it is in every sense true that the jiublic have become 

 more kindly inclined towards rubber heels, it is true that they 

 have been quietly if unconsciously aided in changing their minds 

 by some rather interesting and unusual trade conditions. As we 

 have said in the foregoing, only the cheaper grades of leather 

 went into foplifts and heeling, and of course only the poorest kind 

 of wear resulted. This did not satisfy purchasers of footwear and 

 they soon learned that a good rubber heel would outwear several 

 pairs of poor leather or paper heels. .'Xbout this same time the 

 shoe manufacturer awakened to the fact that with his factory 

 properly organized and his heeling gang working harmoniously 

 by the machine nailing method, it was less costly to make shoes 

 with rubber heels. To appreciate this statement properly one 

 must understand the several processes and parts that go to make 

 up the heeling operation and the heels. 



A complete leather heel consists of several separate and distinct 

 parts known as a rand or "dutchman" (Fig. 1), a base (Fig. 2). 

 which goes on top of the rand, and a toplift (Fig. 3), which is 

 the topmost lift of the heel. Shoe manufacturers formerly made 

 their heels complete in their own factory but now they buy these 

 .several parts from as many different specialty manufacturers be- 



