Do you mean SS and AL fasteners, or standard fasteners joining SS and AL?
What you really need is the coefficient of friction, which is difficult to estimate even with "normal" steel fasteners. All of the table you see on the net are based on assumed coefficients of friction. If this is a critical application your only choice it to measure this on a per case basis.
I think we'd all like a fastener torque chart on the wall just to look up the required torque but that's just not how it works...and no one wants to take the liability for putting out said chart.
I am working on the chart in Manufacturing instruction to tell assembler what torque to use. We are using Stainless steel and plastic fastener that goes into aluminum or stainless steel thread. I don't want to make scientific project out of it. I am sure every company that assembles something hase some kind of assembly instructions with torque table and I thought it would not be a big problem to find this info on web.
Thank you,
Boris.
I used a spreadsheet to build a screw torque table.
Build a spreadsheet. Add all your screw sizes. You can find charts that show the stress areas. If you have Bickford and Nassar's Handbook of Bolts and Bolted Joints you will find formulae for stress area that accounts for the possibility of UNJ and MJ series screws.
On the spreadsheet, list all the assumptions you made. What is the yield or proof stress of your screw material? This is not a simple question for stainless steel. How is your joint lubricated? Are your screws tapped deep enough that they will fail in tension? What percentage of proof stress are you using to calculate force?
Quite a few years ago, I ordered a torque wrench that came with a manual which included torques for cap screws. I worked everything out, and I determined that the torques were for unlubricated joints at 90% of proof stress.
Drawoh,
If it is not proprietary, can I get a copy of your spreadsheet? As I mensioned before, it is for manufacturing instruction, and general numbers will be OK.
Thank you in advance.
Boris.