Shear resistance of the M16 bolt in the bench for the workshop press

Question

I made a hydraulic press. The actuator can push 70 tons. I wonder how many bolts should the M16 8.8 bolt table be mounted on. Currently, the table is on four screws (one for each corner of the table). How much can one M16 8.8 bolt withstand (I cannot mount the rod, there must be bolts)? Photo...

jalop · Accepted Answer

The shear capacity of an M16 class 10.9 bolt in the threaded section is 62.80 kN. You need these 6 screws, 3 on each side.

sanfran · Accepted Answer

If I count correctly, one M16 bolt with characteristic 10.9 has a shear strength of 120kN.
Assuming that the tensile strength is 1000 N / mm2 - 1000000000Pa (one billion Pascals), the active surface area is 200 mm2 (0.0002 m2) and the factor is 0.6.
Since the area of the threaded part may be slightly smaller, and you need to add a safety margin, I would suggest multiplying the result by 0.6, which will give us about 70kN per bolt.

Please check my arguments.

jalop · Accepted Answer

Depends on whether one bolt goes through and is sheared in two places? If so, you need 6 screws. If not, then you need twelve screws.

sanfran · Answer

Are there any features stamped on the screws or are they made of Chinese g ** nolite? There are formulas to calculate this, but you need to know the bolt feature.

liku025 · Answer

@sanfran. I bought such screws. There was no longer any stronger. As you can see, I have two types. Is anyone able to answer my question above?

liku025 · Answer

I am very grateful to you! Need 6 screws in total? Because I've already drilled a total of 12 3 for each of the four table legs

Anonymous · Answer

First of all, counting the screws, you take the core diameter, not the nominal size by adding the above funny comment ... it's a bit of a difference of 30% The second thing is that it is not pure shear, but bending with shear plus the Huber / Richard von Mises hypothesis and the choice of the safety factor ... These are trivialisms at the level of a mechanical technical school.

sanfran · Answer

Therefore, in the formula from post reference # 2 there is a factor of 0.6.
To compensate for the difference between the spindle and the thread, I also chose a factor of 0.6 - as you can see, my technical college news has not yet aired until the end.

Anonymous · Answer

In such a construction, bending dominates, not shear ... pure shear is only for tightly fitted bolts on a cylindrical surface ....

liku025 · Answer

the table fits quite closely to the frame, so I don't know. Will these 12 screws last?

Shear resistance of the M16 bolt in the bench for the workshop press

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