Lubricated Bolts and Reduced Torque
Lubrication effect on bolt tension and torque.
www.engineeringtoolbox.com
Bruce
Reduced Torque with Lubricated Bolts
- Thread starter bcp
- Start date
- Views: 3442
www.engineeringtoolbox.com
Bruce
BravoXray
Elite Member
- Joined
- Dec 17, 2019
- Messages
- 2,593
- Location
- Nothern Indiana
- Tractor
- Kubota BX2230, John Deere 430 Diesel
What about anti-seize?
grsthegreat
Super Star Member
Anti seize also changes torque ratings.
jeff9366
Super Star Member
- Joined
- Jan 14, 2011
- Messages
- 12,777
- Tractor
- Kubota Tractor Loader L3560 HST+ ~~~~~~~~~~~~~ 3,700 pounds bare tractor, 5,400 pounds operating weight, 37 horsepower
Use fine thread bolts and nuts in lieu of coarse thread bolts and nuts.
Streetcar
Veteran Member
Torque is indirect method to determine tension in bolt. Any lubricant will lower torque for given tension on other hand dirt or damage to thread will increase torque for given tension
chim
Elite Member
dadohead
Silver Member
You can find most everything on the internet. The chart above should have been left where it was found though.
I'm a retired tractor engineer and one of my first training assignments was running the bolt lab for our construction machine division. A sign was in the lab: "torque is what we do; tension is what we want." We also want consistency. On the assembly line, every bolted joint is set to a specification. That spec is determined in the lab; MANY bolted joints were torqued to "proof".... meaning: it is the torque (and tension) of a bolt at its yield point. The torque set on the line is then backed off by the plus tolerance of the wrenching system. Consistancy is everything. If a new shipment of bolts differ (supplier, plating, etc) bolts start breaking on the line.
Every kind of bolt finish imaginable is tested: raw, phos & oil, electro plate, mechanical plate, etc. Oiled bolts can be the most inconsistent of the bunch! Most consistent by far: dry mechanical plated.
Do NOT oil any bolt (on purpose) that a manufacturer has published a spec for. Fine threads don't offer any tension advantage either (any advantage is eaten up in additional thread friction)... because of that, they excel in high vibrational applications. Hope this helps.
I'm a retired tractor engineer and one of my first training assignments was running the bolt lab for our construction machine division. A sign was in the lab: "torque is what we do; tension is what we want." We also want consistency. On the assembly line, every bolted joint is set to a specification. That spec is determined in the lab; MANY bolted joints were torqued to "proof".... meaning: it is the torque (and tension) of a bolt at its yield point. The torque set on the line is then backed off by the plus tolerance of the wrenching system. Consistancy is everything. If a new shipment of bolts differ (supplier, plating, etc) bolts start breaking on the line.
Every kind of bolt finish imaginable is tested: raw, phos & oil, electro plate, mechanical plate, etc. Oiled bolts can be the most inconsistent of the bunch! Most consistent by far: dry mechanical plated.
Do NOT oil any bolt (on purpose) that a manufacturer has published a spec for. Fine threads don't offer any tension advantage either (any advantage is eaten up in additional thread friction)... because of that, they excel in high vibrational applications. Hope this helps.
chim
Elite Member
Yup. The chart was probably developed by a guy living in his mom's basement. Perhaps some dude with delusions of adequacy. Or mebbe not:
Allied Systems Company
Allied Systems Company designs and manufactures specialized heavy lift and material handling equipment such as cranes and log loaders to winches and balers.
gsganzer
Elite Member
- Joined
- Jun 11, 2003
- Messages
- 3,093
- Location
- Denton, TX
- Tractor
- L3800 w/FEL and BH77, BX 2200 w/FEL and MMM
I agree with that on a manufactured device. But it's very common in many industries like oil/gas, chemical and power generation that bolts/studs get coated with anti-seize compounds to prevent corrosion and facilitate future disassembly. Although I've always preferred the Xylan (Flouropolymer) coated studs for these applications.
In the instances where anti-sieze is used, there are charts that give the appropriate torque reduction. It's also important to note that the contact surface of the nut should also receive the coating.
Paystar
Elite Member
What I find interesting is all the commercial tire dealers around here, when I'd had tires done on my class 8 trucks they ALL oil the threads when they re-install.
