source/standard that can provide torque values 3

[janeku]

I am interested in a source/standard that can provide torque values for this kind of connections:
Bakelite-Steel
Brass-Steel
Plastic-Steel
Bakelite-Bakelite
Plastic-Bakelite
Brass-Bakelite
Plastic-Plastic
Brass-Brass
Steel-Steel

for responsible and non responsible connections.
Thanx in advance

 

[drawoh]

Janeku,

Are you talking about screw torques?

Any time I see a sheet with screw torques, I re-do the calculations myself. I want to know what assumptions they made when they did it.

-What yield and proof stresses did they use? Stress values for 18-8 stainless steel are all over the place, for example.
-What percentage of proof stress did they use to get the clamping force?
-Did they lubricate or not? (Loctite 242 is a lubricant)
-The screw equations assume that the screw fractures in tension. How deep must the screw penetrate into soft materials like plastic, to ensure this tensile failure?

If you want screw torque tables, you can do it easily with a spreadsheet, once you have collected the information above. Once you have done this, you know were all the information on your table came from.

JHG

 

[CoryPad]

Loctite Product 242 is a thread adhesive, not a lubricant. When used on a screw, it may lower friction coefficient, but that is not its purpose.

 

[MASSEY]

Loctite 242 may not be a lubricant, but if it lowers the coefficient of friction - it must be treated as one. Not because "Loctite 242" was used, but because the coefficient of friction has been decreased which obviously tremoundously affects screw torque values.

 

[janeku]

Thanx for a advice Mechanical. I weas hoping that there are some tables that gives requested values. This screw connections are for screws M3 to M6 PZ, PH, and normal head.
They are used in contactor assembly procedures. Now, it is recomended that we should use torques defined with steel-steel connections (for ex. M4 - we must use 1,6 Nm for bakelite-steel connection) but I think it is not valid for this kind of assembly.