warped aluminum mold

[farmbif]

was just looking though s&s and saw one seller claims is a warped noe aluminum mold.
is this a common occurrence
caused by using hotplate to preheat maybe
the noe alum mold I use most is his copy of 35-200 4 cavity and it works great, never a problem and I never used a hotplate

[Targa]

If he warped the mold it’s user error by either dropping it or heating it to high on a hot plate.

[243winxb]

The maximum operating temperature should be limited to 400 degrees with the absolute maximum of 450 degrees, for a maximum of 30 minutes. At 450 degrees the pins will turn a pale straw-yellow. Any temperature above this will excessively reduce the tensile strength of the aluminum block by annealing. Once this overheating occurs, the only option is to send it in for replacement.

The aluminum molds will not overheat by simply casting but can be overheated by preheating with a hot plate, torch, setting on top of the pot to heat up or immersing in molten alloy for an excessive amount of time. https://support.leeprecision.net/en/knowledgebase/article/alignment-pins-fall-out-overheating-double-cavity-mold

This includes Iron Molds also.

[45DUDE]

I have clamped aluminum molds and heated to remove warp. Let cool naturally. You may have to do more than once but keep tightening. Hold it up to a light. You can tell when the warp is gone.

[uscra112]

All this time I've never known you could warp an aluminum mould.

[deltaenterprizes]

I have a 10 cavity H&G #50 38 wadcutter mold that is warped. It came from a prison where the inmates cast boolits for training!
I have been working on it a little at a time but I think it will become a core mold for 44s or 45s!

[uscra112]

A long time ago I watched a skilled machine tool mechanic straighten a bent leadscrew with an acetylene torch. He knew just how much heat to apply and where to warp it straight. Incredible. 'Course that was steel, not cast iron.

[45DUDE]

I have a 10 cavity H&G #50 38 wadcutter mold that is warped. It came from a prison where the inmates cast boolits for training!
I have been working on it a little at a time but I think it will become a core mold for 44s or 45s!

Have you thought about Putting several clamps on and put in an oven? Let it cool and tighten and do it again? --Just a thought. I have a 6 cavity and it makes me tired. You have a chunk of iron.