Weld fillet size suggestions

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Ok so basically we have 16mm(5/8") steel plate welded onto PFC channel with a wall thickness of 10mm(3/8").  The part will have to endure large forces.My boss and I have different opinions on this so id like to see what others sayUsing a MIG welder what would people say should be the leg length of the fillet welds?
Reply:Following what I learned here in university the correct size would be Where a is leg size and t is thickness of the metal. So a leg size of 7mm is actually the biggest that is recommended. And a minimum of 3.5mm is as small as possible. That being said I'm no welder I'm studying engineering. Hope it helps Phil
Reply:Originally Posted by porkncheeseOk so basically we have 16mm(5/8") steel plate welded onto PFC channel with a wall thickness of 10mm(3/8").  The part will have to endure large forces.My boss and I have different opinions on this so id like to see what others sayUsing a MIG welder what would people say should be the leg length of the fillet welds?
Reply:Can't really answer without more specific info on loading.  "large" forces doesn't help.  That said, the weld won't be any stronger than the thinner of the two members.  So making the weld size larger than 10mm does no good.  Unless you've got more info, I suggest making the weld size 10mm, and moving on.  If you are welding a large number of these parts, and the size of the weld will have a big effect on the labor and material costs, then it makes sense to refine the design for the smallest weld that will provide the necessary strength.  To make this calculation you need to know the forces applied to the joint, the strength of the base metal, the strength of the filler metal, the size and thickness of the base materials, and the geometry of the weldment. Originally Posted by porkncheeseOk so basically we have 16mm(5/8") steel plate welded onto PFC channel with a wall thickness of 10mm(3/8").  The part will have to endure large forces.My boss and I have different opinions on this so id like to see what others sayUsing a MIG welder what would people say should be the leg length of the fillet welds?
Reply:Originally Posted by A_DAB_will_doCan't really answer without more specific info on loading.  "large" forces doesn't help.
Reply:Sorry guys. There is a lot of detail which I didn't wan to get into. Rather just wanted peoples initial thoughts.Thank you "A DAB will do" for your very helpful response.The boss specified 6mm welds. I didn't say anything but I was thinking they should be 10mm welds because it is some kind of tow hitch assembly for trucks. There are 30 of these which makes your point valid. My only concern was it failing and causing a catastrophe. My boss has obviously taken into account profitability along with many other factors and details of the tow hitch operation loads, forces, etc. He is a smart man. That's why he is boss.Thanks again for not being rude and helping me see it from a business point of view.