566 



THE INDIA RUBBER WORLD 



[July 1, 1916. 



METHODS OF TESTING COTTON FABRICS AND 

 RUBBER PRODUCTS. 



COMMITTEE D-13 of the American Society for Testing 

 Materials presented tentative methods of tests for con- 

 sideration at the annual meeting held at Atlantic City, New 

 Jersey. June 27-30. 



TESTING COTTON FABRICS. 

 The tentative tests for automobile tire fabrics submitted last 

 year by the committee have been amended and continued as 

 "Tentative General Methods for Testing Cotton Fabrics." 

 The new features included are : 



1. Definition of "Dry Condition" and "Standard Condition" 

 with respect to moisture. 



2. Method of determining the thickness of the fabric. 



3. Two alternate methods, designated as "grip" and "grab," 

 for determination of tensile strength. 



DEFINITION OF MOISTURE. 



Dry Condition. The dry condition of cotton material shall 

 be understood to be absolute dryness obtained by material 

 placed in a ventilated drying oven maintained at a temperature 

 of 221 to 230 degrees F., and dried to constant weight as deter- 

 mined by two consecutive weighings not less than ten minutes 

 apart, and showing a further loss of not more than 0.1 per cent 

 of the previous weighing. 



Standard Condition. The standard condition of cotton mate- 

 rial shall be understood to be the condition in which it contains 

 8.5 per cent of its dry weight of moisture. 



THICKNESS OF FABRIC. 



The thickness shall be measured by an automatic spring mi- 

 crometer which presses upon at least 0.5 square inch of the 

 fabric with a uniform constant pressure, and which is so 

 mounted as to make measurements 6 inches from the selvage. 



At least 10 measurements at different portions of the roll or 

 piece shall be made, and the average shall be the thickness of 

 the fabric. 



TENSILE STRENGTH TESTS. 



Strip Method of Test. The test pieces of fabric are taken 

 as shown in The India Rubber World (August, 1915, page 612), 

 and are ravelled to the specified threads per inch. 



Grip Method of Test. The test specimens shall be taken as 

 follows: Starting at a line in the center, warpwise, lay ofif 



h2'\ \<- S" 



Location of Test Specimens, Grab Method. 



adjacent to this line five specimens on one side, parallel to the 

 line (warp) and five specimens on the other side perpendicular 

 to the line (filling). The test specimens shall be cut 5 inches 

 long by 2 inches wide. The specimens are not reduced in width 

 by ravelling, but are broken in a clamp that grips 1 inch width. 



Where material requires special treatment, the committee in- 

 tends to prescribe specific methods and tests which will be given 

 precedence over the general methods. Two such tests have 

 been prepared, one for automobile tire fabrics and the other for 

 hose and belting duck. 



AUTOMOBILE TIRE FABRICS. 



The count per inch is determined by aid of the count scale 



shown in The India Rubber World (August, 1915, page 612), 

 and the strength determined by the "Strip Method" in the "Dry 

 Condition" mentioned above. 



FABRICS FOR HOSE AND BELTING. 



The use of the "General Tentative Methods" is required, with 



the special requirement that the strength shall be determined by 



the "Grab Method," and the specimens, when tested, shall be at 



standard condition as defined above. 



Fig.3. 



RUBBEE EXPANSION MOLD IN METAL SHAPING. 



The elasticity of rubber is utilized in shaping sheet metal 

 objects in the die press. The operation of drawing or form- 

 ing is a simple matter where the shape of the piece is such 

 that it will clear the dies, and may be readily removed after 



forming. Many 

 styles of brass 

 bed ornaments, 

 alarm clock 

 and cheap 

 watch eases, 

 parts of gas 

 and electric 

 fixtures, how- 

 ever, are of 

 such shape 

 that the open- 

 ing is smaller 

 than the main 

 diameter of the 

 piece. Such 



articles are first drawn in the form of a shell, and then shaped 

 by an expanding portion, made of rubber. Such an operation 

 is here illustrated. Figure 1 shows a shell of metal. Figure 

 2 shows the same shell, after being expanded in the dies 

 shown in Figure 3. 



The shell is placed in the die surrounding the upper plunger 

 a, the rubber washer b, and the upper part of the 

 lower plunger c. The punch, or upper die d is then brought 

 down by the action of the press. The lower plunger c descends 

 against the pressure of the two coiled springs until it strikes 

 the bed plate and can go no further. As the descent of the 

 punch d continues beyond this point, the plunger a is forced 

 down against the rubber cushion b. This action causes the 

 cushion to expand laterally, thus forcing the shell to fill the 

 annular space formed when the punch d has descended to e. 



Upon the rising of the punch the coiled springs and rubber 

 washer resume their original form, and the finished piece. Fig- 

 ure 2, is removed. 



The rubber for this work must be of a quality which will stand 

 a very considerable distortion without breaking, but sufficiently 

 tough so as not to wear out too rapidly. 



BRAKE LINING CTITTER. 



This is a small, compact, hand-operated machine of 

 strength, constructed to accurately cut brake linings with 

 and despatch. The eccen- 

 tric device that operates 

 the shear blade requires 

 very little effort to cut f^ x 3 inch 

 lining with one stroke of the lever. 



The machine is compact, weighing 

 only 17 pounds. The measurements 

 are : Length of blades, 3Vs inches ; 

 length of bed, W/z inches; height of 

 bed, 6Vz inches; length over all, including lever, 18 inches 

 intended to be attached to a bench or convenient table. 

 Peck Stow & Wilcox Co., Cleveland, Ohio.) 



great 

 ease 



[The 



