Calculating Tightening Torque for M6 Metal Thread Insert in Plastic

[Analysis]

Dear all

I need to calculate the tightening torque for the metal thread insert in the plastic base material.
Is there any empherical relation avail?
M6 metal thread insert /10mm length in the plastic material.I asked to recommend the thread tightening torque..

I found relation referring one book (3.14*d^2)/2 *len*Shear stress of the plastic matl.
Shear stress recommendation 0.5 x Tensile strength(115n/mm^2-actual value got from testing) given in the same ref.book
I found that it is near to steel shear sress..i hope data given is wrong...
I think this torque is the maximum at which failure?

So i have to recommend less than this torque.

Result of the tightening torque found high...

I need suggestions & materials...

Prakash

 

[Achy47]

Dear Prakash,

Thank you for your inquiry about calculating the tightening torque for a metal thread insert in plastic base material. There are a few things to consider when determining the appropriate torque for this application.

Firstly, it is important to understand the purpose of the metal thread insert. Is it being used to strengthen the plastic material or to provide a more secure thread for fastening? This will affect the recommended torque value.

Secondly, the type of plastic material being used is also a crucial factor in determining the appropriate torque. Different plastics have different strength and stress properties, so it is important to know the specific type of plastic being used in order to make an accurate calculation.

In general, the recommended tightening torque for a metal thread insert in plastic material is based on the shear strength of the plastic. This is because the main concern is preventing the thread from pulling out of the plastic material, which would be a result of shear stress. The formula you mentioned (3.14*d^2)/2 *len*Shear stress of the plastic matl) is a good starting point, but it is important to ensure that the shear stress value being used is appropriate for the specific plastic material being used. The recommended torque should be less than the maximum shear stress value.

In addition to the shear stress, it is also important to consider the tensile strength of the plastic material. The torque should not exceed 50% of the tensile strength to avoid potential failure.

I recommend consulting with a materials engineer or using a torque calculator specifically designed for plastic materials to determine the appropriate tightening torque for your specific application. It may also be helpful to conduct some tests to confirm the recommended torque before implementing it in production.

I hope this information helps. Good luck with your project!