Luke Rickert
Hot Rolled
- Joined
- Oct 24, 2007
- Location
- OSLO
Hi I am working on product (a small coffee roaster) that uses a stainless steel drum around 300mm in diameter and 150mm deep (that is 12 and 6 inches) made from 2mm 304 stainless steel. It is not a complete ring but rather 3/4ths of a circle or a C shape if that makes sense and it is supported on both sides with welded tabs. There are number of cutout, holes etc in the part and what I would like to figure out is what is the best production approach and with that approach what sort of tolerance is reasonable. The the dimensions of interest are basically how round it is as we use a paddle inside that rotates and stirs the beans. The challenge is we want to lip of the paddle close to the outside without hitting and if that surface is all over the place that isn't easy and the temperatures are too high to use any normal flexible material on the ends of the paddles. Also this thing is has a good bit of hot air blown into it so there is going to be some amount of movement from the heating (The air enters at around 400C and brings the beans up to a bit over 200C.)
We have had a few different prototypes made and most of them use a series of bends (ever few degrees) but this is not ideal as there is a section with many small holes so these turn into a bit of a cheese grater with the distinct bends. We also have a version that was rolled and while the curve is smoother it seems to be really inaccurate in terms of roundness and straightness. (radially I see a difference on the order of 4mm as you go around and side to side) These samples were made by a rather poor quality supplier so I am not sure if these results are representative or not.
The other methods I have considered are things like spinning and deep drawing but I think spinning isn't well suited and for deep drawing and other forming processes (hydro forming, super plastic forming, the tooling costs are far too high for the projected volume (400 per year and prices that real people, rather than the military are going to buy).
My preference would be to redesign and make everything out of cast and machined iron but that isn't likely to happen.
I can share some pictures etc directly but would rather not post them online.
thanks
Luke
We have had a few different prototypes made and most of them use a series of bends (ever few degrees) but this is not ideal as there is a section with many small holes so these turn into a bit of a cheese grater with the distinct bends. We also have a version that was rolled and while the curve is smoother it seems to be really inaccurate in terms of roundness and straightness. (radially I see a difference on the order of 4mm as you go around and side to side) These samples were made by a rather poor quality supplier so I am not sure if these results are representative or not.
The other methods I have considered are things like spinning and deep drawing but I think spinning isn't well suited and for deep drawing and other forming processes (hydro forming, super plastic forming, the tooling costs are far too high for the projected volume (400 per year and prices that real people, rather than the military are going to buy).
My preference would be to redesign and make everything out of cast and machined iron but that isn't likely to happen.
I can share some pictures etc directly but would rather not post them online.
thanks
Luke