Old foreman in Cleveland proved me wrong about riser placement

I always thought risers should go right at the thickest part of the casting... but a guy named Dave with 30 years in showed me a spot 3 inches off center that fed better and cut my scrap rate in half on a 500lb ductile iron job last month. Has anyone else had luck breaking the usual rules on riser placement?

4 comments

4 Comments

rowan_ross1mo ago

Read in a foundry engineering newsletter that a guy in Ohio shifted his risers to what they called the "hot spot offset" and dropped his scrap from 12% down to under 3% on a 400lb casting. Something about the natural flow path and where the last pocket of liquid metal actually collects, which is rarely the absolute thickest section. Makes sense when you think about it, a lot of those old rules were made for smaller parts or different alloys. Ductile iron especially seems to do weird things if you just follow the textbook.

skyler_johnson321mo ago

Put a thermocouple in the riser neck next time you pour one of those 400 pounders. You'll see exactly when the last bit of liquid metal actually moves, and it's never where you think it will be. @rowan_ross that Ohio guy probably saved you a lot of trial and error.

the_laura16d ago

That 12% down to under 3% is wild. I had to read that number twice. A 9% scrap reduction on a 400lb casting means you're saving something like 36lbs of metal per pour minimum, not counting the labor and energy wasted on bad pours. I've seen guys chase that last 2-3% for years with gating tweaks and never get close to that kind of jump. Did that newsletter mention what kind of ductile iron grade they were running, or if they had to change their pouring temperature at all to match the new riser location?

thomas.river1mo ago

That 3 inch offset thing lines up with what I've noticed about a lot of "hard rules" in life - the obvious answer is usually close but not quite right, and the real sweet spot comes from watching what actually happens a few times.