yang686526

torque callouts
is there a particular standard that gives the requirements for calling out torque values on the drawing? when i worked for a military contractor, we used a table with roman numerals and their corresponding torque values. where i am now just calls the torques out next to the fastener callout. please help.
as far as i know, you just call it out in the notes using whatever units you use.
chris
systems analyst, i.s.
solidworks/pdmworks 05
autocad 06
i've done it by creating a table and placing the values in notes. i think notes give a little more room for an explanation on the preparation before the bolt is torque. for example, clean threads before applying anti-galling lubricants (molybdenum disulfide). but then i've also called out assembly procedures in notes. i would say follow your company's drawing format but cover all aspects of the assembly process
best regards,
heckler
sr. mechanical engineer
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never argue with an idiot. they'll bring you down to their level and beat you with experience every time.
right now, we don't have a set drawing standard. i'm trying to get one started by using the asme standards as guides.
thanks for all of the input.
starchief-
don't forget to provide reasonable tolerances on the torque values!
tunalover
so if the drawing call-out states "torque to 45 to 55 lb ft", what does the technician set the wrench to?
mintjulep raises an important issue.
a target torque should be identified. this is what an operator would use.
a torque range can be specified for quality control purposes. another person in qc would use this range to inspect the process.
the relationship between target and inspection limits should be developed with actual data from actual parts.
regards,
cory
just like any other tolerance, "torque to 45 to 55 lb ft" would be set at 50 while qc would inspect 45-55. always shoot for the nom.
chris
systems analyst, i.s.
solidworks/pdmworks 05
autocad 06
we place the torque call out on the fastener right next to the balloon on the drawing. this makes it easy, as someone looking at the drawing and assembling the product does not have to leave that area on the drawing and locate another table to get the torque info. some of our drawings can be quite large and span mulitple sheets. also, regarding torque tolerances, keep in mind that a typical torque wrench is only accurate to within +/- 30 to 35%. its best to place a torue value on the fastener that is safe for the tool that is intended to tighten the fastener. other methods of more accurate tightening of a fastener can be used, but are generally more costly. i like the approach of designing in an acceptable range so that the least expensive method can utilized and still have a quality design. of course, this is different for every company's products and the environment they operate in.
pete
ok, so assuming a micrometer-adjustmet type torque wrench, the wrench setting can be set to the desired "nominal" value of 50 lb ft every time. so the guy pulling the wrench has no need for a tolerance, he needs to know what to set the wrench to. why make him do math?
the concept of a qc torque check on an already tightend fastener is rediculous.
so, the only possible use for a torque range on an assembly drawing is to qc check the calibration of the torque wrench.
the range on the dwg has nothing to do with qc checking the wrench calibration. if you don't want a tol specified...good luck to you.
chris
systems analyst, i.s.
solidworks/pdmworks 05
autocad 06