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Spaenaur Catalog 14 - Digital Flipping Catalog
CATALOG 14 B P : 1-800-265-8772 F : 1-888-252-6380 www. .com Inch Pouce Torque Data - 1960 Series B177 B *These tightening torque values are 75% of the torque required to yield the screw, and apply only for the conditions listed below. Different percentages of torque-to-yield values are also commonly used for special conditions. TENSION INDUCED IN SCREWS BASIC TORQUED AS RECOMMENDED RECOMMENDED TIGHTENING TORQUE *).SBL/HCNI( ).SBL( WERCS LANIMON SIZE DIAMETER UNRC UNRF UNRC UNRF 0 0.0600 – 190 – 2.6 1 0.0730 280 290 4.5 4.8 2 0.0860 390 410 7.5 8.0 3 0.0990 510 550 11.0 12.0 4 0.1120 630 690 16.0 18.0 5 0.1250 830 870 24.0 24.0 6 0.1380 950 1,070 30.0 34.0 8 0.1640 1,460 1,550 55.0 58.0 10 0.1900 1,840 2,100 79.0 90.0 1/4" 0.2500 3,530 4,040 200.0 230.0 5/16" 0.3125 5,820 6,450 415.0 460.0 3/8" 0.3750 8,620 9,770 740.0 845.0 7/16" 0.4375 11,830 13,180 1,190.0 1,305.0 1/2" 0.500 15,760 17,800 1,800.0 2,065.0 5/8" 0.6250 23,740 26,890 3,400.0 3,800.0 3/4" 0.7500 35,080 39,150 6,000.0 6,750.0 7/8" 0.8750 41,590 45,830 8,250.0 9,200.0 1" 1.0000 54,350 59,662 12,500.0 13,000.0 1-1/4" 1.2500 87,225 96,600 25,000.0 27,750.0 1-1/2" 1.5000 126,450 142,280 43,500.0 49,000.0 NOTES FOR CHART These are average values for standard Holo-Krome 1960 Series Alloy Steel Socket Cap Screws with black finish, tested with hardened steel plates, and hardened nuts with the threads and bearing areas lubricated with plain, medium viscosity machine oil. The relationship between the torque and the induced tension (preload) can be expressed by the empirical formula T= KDP, in which T is the tightening torque in inch pounds; D is the nominal diameter of the screw; P is the tension (in pounds) induced in the screw; and K is the torque coefficient. The torque coefficient is not constant but varies with the material, surface finish and lubricity of the threads and head bearing area of the screws and parts fastened. For the conditions shown above (standard alloy steel black finished screws clamping hardened steel parts), K will range from 0.19 to 0.25. For cadmium plated screws with steel parts, K will usually fall between 0.13 and 0.17. For zinc plated screws K may fall between 0.30 and 0.34. When the thread and head bearing surfaces are covered with certain types of lubricants, or with anti-seize compounds, K can drop as low as 0.05. At the other extreme, combinations of certain materials, such as austenitic stainless steel screws and parts not lubricated or coated, can result in K values as high as 0.35, or more. Because the induced tension can vary considerably from one type of assembly to another for any given torque, the above data should be used with caution – particularly in applications where the control of preload is critical and must be obtained by the torque wrench method. For such applications, the relationship between torque and induced tension should be determined experimentally for the actual parts and lubrication practice involved. TIGHTENING TORQUES. At the tightening torques listed standard Holo-Krome alloy steel 1960 Series screws, used under the conditions described, will be preloaded to approximately 75% of the tension induced at yield. The bearing stress under the head at these preloads will be approximately 80,000 psi, so indentation should not occur when the parts clamped are of steel or cast iron with a hardness equal to or in excess of Rockwell B 85. With softer materials, washers may be required under the heads of the screws to avoid indentation. In applications where screws are subject to fatigue from dynamic loading, the importance of proper preloading during assembly cannot be overemphasized. The proper preload is especially important for rigid-type (metal-to-metal) joints, where it has been found that the use of a preload greater than the external load will usually eliminate the possibility of fatigue failure. For this reason, the preferred practice for such assemblies is to preload to 75% of the induced tension at yield. FOR FLEXIBLE TYPE JOINTS, HOWEVER, AND FOR ASSEMBLIES EXPOSED TO ELEVATED TEMPERATURES, MUCH LOWER PRELOADS MAY BE REQUIRED. No general recommendations are possible for such assemblies or service conditions. Each application must be analysed individually, because the preload requirements may vary considerably from one application to another. Users who desire suggestions for the preload or tightening torque to be used for a specific application are invited to contact your Spaenaur Sales Representative. TORQUE-TENSION TIGHTENING TORQUE DATA SOCKET HEAD CAP SCREWS - TORQUE DATA - 1960 SERIES ® 23 JAN 2018 Valeurs de serrage – série 1960 F : 1- 8-252-6380 service@spaenaur. © 2018 Spaenaur Inc. All rights reserved. Catalog may not be reproduced, in whole or in part, without the written permission of Spaenaur Inc. Subject to Catalog Terms and Conditions of Use available at Spaenaur.com and on page TC2 and TC3 at the back of this catalog. © 2018 Spaenaur Inc. Tous droits réservés. Le catalogue ne peut être reproduit, en tout ou en partie, sans l’autorisation écrite de Spaenaur Inc. L’utilisation est soumise aux Conditions d’utilisation du Catalogue disponibles sur Spaenaur.com et à la page TC4 et TC5 à la fin de ce catalogue.