I intend to make some bending fixtures for use in my 50 ton hydraulic press. The maximum i would be bending 3/8 x 6" hot roll plate. The stock i have on hand is 1144 and 4140. Any ideas on thee best choice of material for this project?
1144 stresspreoff is a delight to machine. Use it if you don't need exceptional poperties, like long die life.
4140 can be more durable if properly heat treated.
Strongest, machining either is not a problem. They will see limited use and no heat treating after machining. They will be used once in a while when i need to make a bracket etc. Saftey is my main concern, i don't want to encounter an unexpected failure and have steel flying around my shop.
Tool life is not a concern as these will be used maybe 4 times a year to make an odd bracket i need. Does the 5 times saftey factor apply to 1144? Say i want to bend 1/4" x 3" hot roll to 90 degrees will the punch and die have to be 1-1/4" width to be safe?
You're using the "that should be plenty strong" method. I'd go with that. I would cheet on the punch a bit if needed.
A whole pickup load of punches and dies fell in my son's pickup on his way home from work, about three feet each of every conceivable style. Happens to be the exact width of my hydraulic press. I'll never need to build one.
It depends on how and how much you're going to load it. 4140 is a lot stronger but the question is whether you need the strength.
Comparing them in the normalized condition, which is a common condition in which they're sold, 4140 has about 35% more tensile yield strength, a few percent more hardness, a few percent more elongation before it breaks, and about 20% - 25% more impact strength.
4140 is both tougher and stronger than 1144. Again, though, the question of which is "best" depends on whether you'll gain any practical advantage from the extra strength.
You're welcome, Tom. I've never bent anything as thick as 3/8" in a brake, but it's gotta be a load on the fixtures. It sounds safer to go with the 4140, not knowing what the loads actually are.
And if that doesn't handle it, you can get your second set heat-treated for a big boost in strength.
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