Had a defective mold box that jacked up 40 castings before I found the flaw

I ran into this problem at the shop last month where our green sand molds kept coming out with this weird shift pattern on the cope side. First I blamed the pattern plate, then the flask pins, wasted like 2 full days chasing my tail. Turns out the mold box itself had a hairline crack along the matchplate that was throwing everything off by maybe 3 millimeters. I felt pretty dumb when I finally caught it, but nobody else on the crew spotted it either. Took me about 14 hours of staring at castings and measuring stuff to figure it out. What's the weirdest hidden defect you've ever found in your equipment lol? Has anyone else dealt with a similar issue where the problem was right in front of you the whole time?

3 comments

3 Comments

kai_ramirez383d ago

Bro I found a cracked squeeze board once that was only visible under a specific angle of shop light. Took me three shifts to realize it was flexing just enough to ruin my drag halves. Felt like a MORON when I finally spotted it.

zarag173d ago

Was it one of those aluminum ones or the older steel boards? I've had aluminum screens that hide cracks like nobody's business since the anodizing blends everything together. You check it with a straight edge and it looks fine, but the second you put tension on the mesh it starts creeping. What did you end up doing, replace the whole board or try to weld it? I'm always curious if people bother with repairs on those things or just toss them.

torres.riley3d ago

Dude I spent a whole afternoon once chasing a shift that turned out to be a burr the size of a grain of sand on the matchplate. Felt like a real genius when I finally ran my finger over it and there it was. 14 hours of staring at castings sounds about right for this kind of detective work. At least you found it, I've had molds that took me damn near a week to figure out because the crack was hiding under a layer of dried release agent.