Tightening torque for socket head countersunk screws

[MANUSEYMOUR]

Hi, we are having trouble with M2.5 socket head countersunk screws grade 10.9. I cant seem to find any literature that applies directly to countersink, can find all the info on bolts, self tapping and pozi-pan head but no where can I find info on the tightening torque to be applied to countersunk screws.

I have contacted suppliers directly and they also cant find this info.

We are having hug trouble with these just rounding off when we are inserting these into our product so assume I am applying the wrong torque but as said earlier I cant find info to give me the correct value anywhere.

Thanks in advance for your help.

[Kelly_Bramble]

See the following:

Countersunk Screws Torque Table Metric, ISO

This is a recommended torque per DIN 7991 and ISO 10642 for Countersunk screws.

[MANUSEYMOUR]

Came across this already but if you notice the standard does not go down to M2.5.

[Kelly_Bramble]

Came across this already but if you notice the standard does not go down to M2.5.

So, from the table did you extrapolate the torque for a 2.5? Here's a link to other fastener torque design equations.

Engineering Fastener Torque Specifications


Usually torque fro static load applications is based on 90% utilization of minimum yield of the material.