Maximum tightening torque for metric self tapping screws

Hi all,

Can someone help me to find out the maximum tightening torque for metric self tapping screws.

Actually I am using M3, M4 and M5 ST screws for fixing the plastic parts together.

Now I am going to prepare assembly guideline document for each SKU, So there I need to mention the tightening torque of each screw which is used in assembly. But I am not getting the direct values of torque.

I got the analytical calculations to find out the require tightening torque when clamping force is known but I am interested in maximum tightening torque which can be applied on screw.

Have a great time...

Thanks,

Navy