How to calculate the tightening torque of bolt quora. The minimum length of engagement meffmax is calculated with rmmax, dmin and d2max or d2min and. So, when the clamping of a joint is critical, then it is best practice to add additional clamping force more bolts or if that isnt possible, then to study the torque to tighten vs. Maximum tightening torque for metric self tapping screws. Additionally, the bolts and flanges must be robust enough to prevent warpage, distortion or. Calculation of the torque mal and axial force fl on the thread. Approximate values for metric co threads vdi 2230 bossard group bolt torque chart pdf zenam vtngcf org iso bolt torque chart zenam vtngcf org approximate values for metric co threads vdi 2230 bossard group. Fc29 2 proper bolt axial tightening force and proper. Tightening the nut stretches the bolt, which increases the load on the gasket. As mentioned above, the tightening torque is for practical reasons the criteria normally used to specify the prestress in the screw. However, we usually measure the tightening torque, which is dynamic resistance. General information on torque specifications the amount of torque applied to a bolt or nut determines the clamp load. Pocket guide to tightening technique this booklet provides an introduction to the technique of using threaded fasteners for assembling components, the ap. This calculation is only to be submitted when requested by the society.
Proper torque and axial force for mild steel pieces tightened together by means of a hexagon socket head cap screw, m6strength class. Tightening torque retightening torque inspected by ctb model retightening by peak method a, c point retightening torque by bottom method b point the retightening torque first starts with the rotation of the head only, and then causes. Several factors affect how much tension occurs when a given amount of tightening torque is applied. A method for calculating plastic clamp force from tightening torque was presented by considering a bilinear model obtained from experimental tightening torque clamp force relationships. This graph is interpreted to determine the precise maximum driving and stripping torque. When a bolt is tightened, by applying a torque to the bolt head or nut, the bolt. T the purpose of tightening screws is to fix one object to another object. Generally, tightening torque means the c point method. This is due to its simplicity and its widespread understanding by all engineers. It is extremely important to realize that this tightening value is valid only so long as all of the aspects of the application remain constant. The tightening torque is the torque at which it is recommended the application be assembled. This presupposes that the torque wrenches required for this are subjected to a regular inspection.
Technical data suggested tightening torque1 values to produce corresponding bolt clamping loads notes. However, only about 10% of the torque applied is transferred into clamping force. Manager engineering 10 january 2007 uncontrolled on printing page 4 of 10 asnzs 2451. Physical properties nominal thread size stress area 5. Bolt tightening 2 bolt tightening 21 various tightening methods various tightening methods 34 22 screw and torque relation formula between screw and torque 35 23 torque coefficient 1 formula of torque coefficient 36 2 the torque coefficient is not stable 36 3 even when the torque is stable, axial tension may vary 36 24 method for determining tightening torque.
It is a measure of how much force acting on an object which causes that object to rotate. These figures represent an estimate of torque torque being the measurement of friction, not tension required to induce given preload clamp load in a bolt for noncritical. Tightening torque values are calculated from the formula t kdp, where t tightening torque, lbin k. Tightening torque mai nmm of the grub screw as per bossard t. A method for calculating plastic clamp force from tightening torque was presented by considering a bilinear model obtained from experimental tightening torqueclamp force relationships. Friction points should always be lubricated when using the torque tightening method. The threaded section of the bolt should extend past the nut for this method to succeed. A case study in torqueangle tightening bill eccles bolt science because of space restraints, a manufacturer of construction equipment found that it was not possible to achieve the performance requirements for a high performance joint by using torque tightening. Backtoback and facetoface bearing sets can be preloaded to adjust bearing rigidity. The gasket must do a number of different jobs well to function properly first, create an initial seal. Ratio between measuring torque and tightening torque approximate value obtained by experiment table 31. D nominal bolt diameter, in and p bolt clamping load developed by tightening. Rev 3409 torquetension relationship for astm a193 b7 bolts and studs tightening torque k 0. Mar 17, 2017 it is important to use the proper torque on your project to ensure safe, reliable joints.
May 16, 20 however, we usually measure the tightening torque, which is dynamic resistance. The remaining tightening force is consumed in friction in the screw joint 40% of the torque to overcome the friction in. The torque applied to a fastener with an antiseize compound pre. A method for calculation of fastener torque specifications which includes statistical tolerancing abstract. This method employs a hydraulic ram placed over the nut and a threaded puller which attaches to the ram. The final tightening sequence is achieved smoothly and slowly. Msa measurement loosening and tightening torque isixsigma. Tightening torque the tightening torque is the torque at which it is recommended the application be assembled. The following equation is the basic equation for the elastic resilience. Breakout torque cannot be accurately calculated, however, depending on conditions it can take up to 2 12 times the input torque to breakout. Tensioning loads and tightening torques chart and guide. A method for calculation of fastener torque specifications. It is important to use the proper torque on your project to ensure safe, reliable joints. Suggested tightening torque1 values to produce corresponding.
The relation between applied torque and axial force or load in a bolt can be calculated as. Apply suitable axial tension it is best to do axial tension control for tightening screw, but actually it is difficult to measure. The big problem is that the load on the gasket cannot be measured directly and easily during installation. If lubrication has been applied to the bolt andor the nut other than the normal protective oil film, multiply the recommended torque by the appropriate factor shown in the table. Suggested tightening torque1 values to produce corresponding bolt clamping loads notes. This is mainly due to corrosion and deformations in the bolt and nut threads.
Extreme caution should be used when using a formula for torquetension relationships. Say you have a 8 inch wrench and figure you are applying 4 pounds of force on the wrench centered at 6 inches from the center of the nut. Hexagon head bolts screws din 931933 metric series dimensions notes. Do not let the seat of a bolt or nut dent the contact area. Clamp load is also known as preload or initial load in tension on. The reason all applications should be evaluated to determine the optimum tightening torque is that the k factor in this formula is always an estimate.
To adopt 70% of the breaking torque as the tightening torque for screw joints. Bolt torque specs in foot pounds or inch pounds this table is based on a torque coefficient, k0. Tightening torque tightening torque tightening torque tightening torque bolt clamping force lbs. Alternatively,use the torque tension calculator on the norbar website which enables fastener and friction conditions to be modified. Pdf bolt torque tightening procedures mohammed mujahed. Maintaining specified tightening torques is vital for performing repair work to a professional standard. Add standard and customized parametric components like flange beams, lumbers, piping, stairs and more to your sketchup model with the engineering toolbox sketchup extension enabled for use with the amazing, fun and free sketchup make and sketchup pro. The calculation of the length of engagement is theoretical in accordance with vdi 2230 and must be checked in real life conditions. Engineering toolbox sketchup extension online 3d modeling. Methods for calculating appropriate tightening torque.
Approved torque testing equipment is listed in the catalogue of. Bolts, screws and nuts with british standard whitworth threads rationalized series. Torque control and torque angle control tightening methods using torque to indirectly control a bolts preload is by far the most popular controlled tightening method. Add the engineering toolbox extension to your sketchup from the. Torquetension relationship for astm a193 b7 bolts and studs. Pdf tightening torque calculation method for plastic. Pdf tightening torque calculation method for plastic clamp. If a screw is lubricated, the friction in the threads and under the head is decreased and the relation between tightening torque and clamping force is changed. The fatigue strength of bolt under repeated load should not exceed the specified tolerance. The monte carlo simulation method is applied to quantify the probability of exceeding the maximum desired bolt exploitation for fasteners tightened to a torque specification. For operation with misfiring, evidence for the acceptance of the loadings shall be proved by calculation.
Here i have come up with excel sheet, which will directly gives the values for tightening torque of self tapping screws. Bolt tensioning a bolt and nut are designed to act together as the internal threaded fastener nut is tightened onto the. Additionally, the bolts and flanges must be robust enough to prevent warpage, distortion or separation during service. Tightening torque values are calculated from the formula t kdp, where t tightening torque, lbin k torquefriction coefficient.
Proper bolt axial tightening force and proper tightening torque. Bolt suppliers sometimes have customers say that their bolts are no. Bolt tightening table table 14 table 15 figure 21 1. Qaxial tightening force for bolt and fatigue limit the proper axial tightening force for a bolt should be calculated within an elasticity range up to load 70% of the rated yield strength when the torque method is. Engineering fundamentals of threaded fastener design and analysis. Bolted joints bolt load and tightening torque when using bolts to fasten the sealing joint the bolts must be of suitable strength and quantity to compress the seal and withstand the maximum hydrostatic load. Bolt tightening technical data bolt tightening 2 bolt tightening 21 various tightening methods various tightening methods 34 22 screw and torque relation formula between screw and torque 35 23 torque coefficient 1 formula of torque coefficient 36 2 the torque coefficient is not stable 36. Torque control and torqueangle control tightening methods using torque to indirectly control a bolts preload is by far the most popular controlled tightening method. Methods for calculating appropriate tightening torque by bossard.
To view the full content, you will need to purchase the standard by clicking on the buy button. Qaxial tightening force for bolt and fatigue limit the proper axial tightening force for a bolt should be calculated within an elasticity range up to load 70% of the rated yield strength when the torque method is used. The tightening torque should be sufficiently high so as to fully drive the screw and generate clamp load, yet low enough to avoid stripping and long term boss damage. The relationship between torque, the turning force, axial bolt force and. Starting with this equation, which defines a linear relationship between torque and tension, you can develop models for the tightening process. Manager engineering 10 january 2007 uncontrolled on printing page 6 of 10 m12 m16 m20 m24 m27 m30 m33 m36 m39 m45. A case study in torqueangle tightening bolt science. Add the engineering toolbox extension to your sketchup from the sketchup. Tightening and loosening torque of the adjusting nut. The maximum axial load on the bearing must not exceed 10,000 n. Metric bolts tightening torques engineering toolbox.
If lubrication is to be applied to the nutbolt,multiply the recommended torque by the appropriate factor shown in the table on page 7. This clamp load is a determining factor in the performance of the assembly. Torque has been converted into ftlbs by dividing the result of the formula by 12 all calculations are for coarse thread series unc. The calculator below can be used to calculate the torque required to achieve a given axial bolt force or load. Coefficient 44 45 rs 3 tohnichi torque handbook vol. Approved torque testing equipment is listed in the catalogue of workshop equipment planning documents. It is required if the natural frequency calculation predicts important resonances within the operating speed range. Underover tightening of fasteners can result in costly equipment failure or personal injury. The application of preload to a fastener by the turning of the fasteners nut. Methods for calculating appropriate tightening torque bossard. Also the attached pdf having updated analytical calculations of required tightening torque of m3 self tapping screw. When loosening bolts a torque value higher than the tightening torque is normally required.