Whoopsie

This can get a little technical, so I’ll try to keep it jargon-less. I had a little goof-up at work. Luckily, not too many people were involved before I cleared it up. It could have been a big mess if I had handled it differently.
We have a customer in Germany who buys our bearings. Years ago we sent them a batch that was heat treated badly, and they were failing. The customer sent everything back and stopped ordering from us for about 5 years. Shipping about 1600 pounds from Germany is expensive, so the owner here was not too pleased. As part of winning orders from them again, they required us to life test our parts before shipping them.
(Bearing primer: Two metals parts rubbing against each other create a lot of friction, which causes heat, which melts metal, which causes the motion stop, the friction to stop, the heat to dissipate, and the melted metal to cool back down as one solid lump. Not good. If you’ve known someone who never checked their engine oil and seized the engine, you have an idea… Putting little balls in between the two parts so that they roll against each other reduces the friction. Using a lazy-susan is SO much easier than sliding things around the table. The simplest bearing is two rings of metal with a little groove in them called raceways. This holds the balls in the right place, kind of like with toy slot-cars. The top ring will now spin quite easily on top of the balls. The bearings we make for Germany are just like this. You put a “jacket” over them to hold everything together. Fill it with grease - I trust you understand the Lube concept - and away you go. If you bake steel, you can make it harder. Harder rings are less likely to wear out, making the bearing last longer. Life testing means to put a bearing in a machine that puts a LOT of pressure on it, and spins it for several hours. The excess pressure makes it wear faster, so you approximate a longer life in a shorter time.)
I am in charge of running the life tests. When the parts come back from our heat treater, I wanted them tagged so people would Tell Me the parts were here. I was told this was a horrible idea, it’ll happen properly anyway. Well, I discovered two weeks ago that we had Thousands of parts in inventory from last October that were just put away with nobody telling me they were here. I was too angry for a proper “I told you so” response. But I started hunting down lot numbers, and testing parts.
Friday I put the last of the samples in the test machine. This morning I went up to take it out of the machine. The computer screen showed this one FAILED. I took the bearing apart and saw one ring was all chewed up and cracked. Not good. Worst case would have been that we shipped a whole batch of parts again that would fail, and it would be a repeat of the 5-years-ago situation. But I seemed to recall this batch showing up after we were done building bearings, and just going into inventory. The engineer suggested testing a second sample. I went to go take another piece. I couldn’t find them. Looked everywhere! Asked the material handler for help. Nothing.
I sent an email to the heat treat place asking for some info on the heat treat lot number. I wanted to verify that these were made after we finished the bearings, so there would be no chance of having sent them to Germany. He wrote back and said that lot was a completely different part number than what I was looking for. Uh oh. I took my one sample piece and measured it. He was right. I had the wrong part number. This part was larger, wasn’t supposed to be tested, and didn’t even fit right in the test. So, of course it failed! Grabbing the wrong part was all my fault, too. I thanked the heat treater guy for his help, told the material handler everything was OK, and then had to fess up to the engineer. Luckily his boss wasn’t in, so he hadn’t told anyone else. If the alarm had already been sounded, it could have started boiling a lot of hot water that nobody needed to be in. But mostly, it just made me feel (and look) like a dumb-ass!