ballen
Diamond
- Joined
- Sep 25, 2011
- Location
- Garbsen, Germany
200 mm AO grinding wheels, 10 and 16mm thick
60 mm center hole
Clamping surface under the blotter is an annulus ID 80mm OD 100mm
Flange clamped with 3 standard M6 cylindrical screws
My question: what is the correct torque for the screws? I'm tired of "tight enough" and want a repeatable process. That's what my torque wrench is for.
In principle a good designer would size/rate the screws appropriately. These are grade 8.8 M6 SHCS, normal tightening torque is 8 Nm = 6 ft-lbs, which generates about 2200 N of force. Since there are three screws, this would provide 6600N of force compressing the flange. That force is spread over an annulus of area 2,800 square mm. So the pressure compressing the grinding wheel would be about 2.3N per square mm. For comparison the compressive strength of glass is about 1000N per square mm.
Is the answer just "look up the normal tightening torque for the flange screws"?
60 mm center hole
Clamping surface under the blotter is an annulus ID 80mm OD 100mm
Flange clamped with 3 standard M6 cylindrical screws
My question: what is the correct torque for the screws? I'm tired of "tight enough" and want a repeatable process. That's what my torque wrench is for.
In principle a good designer would size/rate the screws appropriately. These are grade 8.8 M6 SHCS, normal tightening torque is 8 Nm = 6 ft-lbs, which generates about 2200 N of force. Since there are three screws, this would provide 6600N of force compressing the flange. That force is spread over an annulus of area 2,800 square mm. So the pressure compressing the grinding wheel would be about 2.3N per square mm. For comparison the compressive strength of glass is about 1000N per square mm.
Is the answer just "look up the normal tightening torque for the flange screws"?