idgara73612
Mechanical
I do a lot of sheet metal design, and so inevitably, I have a lot of cases where I cannot meet both the strength req's AND bend radius limits with a certain material. For example, I have an .063 AL 6061-T6 part with a .06 bend radius. That BR is too small for -T6, but can be hit with 6061-O. In this case, I generally define both the initial and final condition (temper) of the material. We have gotten into some discussions lately regarding which of these should be placed in the drawing title block.
My view is that I want to define the FINAL condition in the material spec field. Others say that field should contain the INITIAL condition.
My reasoning for FINAL is that I don't care how you want to achieve it, but at the end of the day I need a part in-hand that meets the dimensions and material spec. In this case, I put the FINAL condition in the mat'l spec field (i.e. 6061-T6 per AMS 4027), and will include a drawing note saying something similar to "Make from 6061-O. After forming, heat treat to final condition shown." I consider this note to be more of a courtesy to the shop guys, but not req'd. If they think they can hit the bend radius with -T6 right off the bat, then go right ahead. If they feel they need to form it in -O then heat treat, go right ahead. Again, as long as it's -T6 when it's finished, I don't care how it gets there.
The shop guys are saying that the INITIAL condition should be the one in the title block, and the notes should identify what the final condition is. They say this more for procurement purposes, so they know to order -O, as opposed to ordering -T6.
Strictly in terms of the drawing, this is about where the discussion ends - but in terms of modeling, it is also beneficial to define the FINAL condition, so that any analyses are done using the correct mat'l properties. And our drawings pull the material directly from the model... so, another point for FINAL condition.
I'm interested in your opinions on this, and if there is any spec anywhere which touches on this. I haven't been able to find one.
My view is that I want to define the FINAL condition in the material spec field. Others say that field should contain the INITIAL condition.
My reasoning for FINAL is that I don't care how you want to achieve it, but at the end of the day I need a part in-hand that meets the dimensions and material spec. In this case, I put the FINAL condition in the mat'l spec field (i.e. 6061-T6 per AMS 4027), and will include a drawing note saying something similar to "Make from 6061-O. After forming, heat treat to final condition shown." I consider this note to be more of a courtesy to the shop guys, but not req'd. If they think they can hit the bend radius with -T6 right off the bat, then go right ahead. If they feel they need to form it in -O then heat treat, go right ahead. Again, as long as it's -T6 when it's finished, I don't care how it gets there.
The shop guys are saying that the INITIAL condition should be the one in the title block, and the notes should identify what the final condition is. They say this more for procurement purposes, so they know to order -O, as opposed to ordering -T6.
Strictly in terms of the drawing, this is about where the discussion ends - but in terms of modeling, it is also beneficial to define the FINAL condition, so that any analyses are done using the correct mat'l properties. And our drawings pull the material directly from the model... so, another point for FINAL condition.
I'm interested in your opinions on this, and if there is any spec anywhere which touches on this. I haven't been able to find one.