In the engine world
aviation and otherwise, fasteners that need full tension will use lubricated threads for the torque. If the tension is not adequate to keep the fastener from coming loose, then locking washers are used. On no other application than aero engines have I seen locking washers. It was proven that with high strength fasteners, that lock washers provide less, not more, security of the bolted joint. circa 1980
To get maximum (and consistent) tension in a bolt lubrication is necessary to get consistent thread friction and lower torsional stresses in the shank.
Some large engines stress the bolt/stud so much that they use hydraulic cylinders to stretch the head bolts all together and then thread a sleeve down by hand with a 1/4" dia rod.
Actually, I was surprised to find that most aircraft fasteners are torqued dry. I learned that they are sized for taking loads in shear. Nearly all engine fasteners rely on tension and contact force to prevent shear movement.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
|
Linear Mode
