Haven't had time to post here much, because ... life. So, I work as an engineer for a living. An assembly that I inherited many years ago, from a colleague, uses a stack of Belleville washers to preload some parts on a shaft. The Bellevilles were chosen from a large national shop that had something in stock that was "close enough". Except they aren't/weren't - when you do the tolerance stack analysis, you end up needing to put either 3 or 4 of them in an assembly, which requires a lot of futzing around in the production shop. And recently, the Belleville shop had a problem getting the parts heat treated, and so the parts have been delayed, for over a month now, which is holding up an order.
So, I spent some time looking for alternatives. Doing the math from the Roark's formulas, we want a stainless washer, somewhere between 0.03 and 0.04 thick, with a 1.53 i.d. and a 2.1 to 2.4 o.d. with about a .120 overall height. And we don't really need to heat treat them, standard 300 series stainless should work. But regardless, these new design springs are going to be custom, because nobody makes them in anything close to those sizes. And the tooling charges, plus minimum order quantities, puts the cost up over $1500 for 50 to 100 pieces (roughly a 1 year supply for us).
So, yesterday and today, I spent some lathe time making a stamping die. Found a scrap chunk of 4140 that was big enough, and cut a 15 degree cone on the mating faces (photos 1 and 2 below), which ended up being too shallow. A second try at 25 degree cone angle ended up giving slightly more dish than we wanted when I stamped a blank I hand-punched out of some .031 full hard 302ss shim stock. But then a quick load test with the arbor press (using a cylinder and pressure gage as a load cell) showed a load profile pretty close to what we wanted - the washer flattened out a bit to end up right in the target dish height, and its gives the right load profile. Success! Now we need to get our local waterjet shop to cut the blanks for us, and we can get back to making shipments.
I think I credit this forum, and its clever engineers and machinists, for inspiring me to give this a try. Hope somebody can make use of the information someday, but bottom line: stamping a Belleville washer is pretty easy, you might make a couple of iterations to get the cone angle right, but then you are in business.
