It's hard to characterize in a single sentence, so I'll just break it down into its constituent parts.
The Beep
When the laundry cycle finishes it does the following:
- It beeps super loudly for 5 seconds
- If you don't run to switch it off, it will wait 30 more seconds and then continue to beep super loudly for 5 seconds
- If you switch it off whilst it's beeping, it will continue to finish its beeping
- There is no volume setting nor any way to switch this off.
The Door
When it's finished. It does not release. That beeping sound from earlier to tell you to come get your laundry? No no no, that was just the "come and watch me drain" alarm.
- Switching it off has no effect on the door release.
- It releases whenever it wants. It could be 5 minutes, it could be 20.
- When it does release, all you will get is a sound, so you better be around to hear it.
- If you miss this sound, it will lock itself again 10-15 minutes later and rotate your clothes.
- It will then repeat the release process.
HELP ME. HE-ELP ME.
Assumptions: For the size a bearing can handle load better, and can be a self lubricating material. Ball bearings are small contact points, and a lot of off center vibration of the machine might wreck the ball bearing. Especially if it gets warm and grease runs out. So they would need to have a much larger ballbearing race like you see on industrial machinery, and the cost probably doesn't justify it.
My dryer seals broke this year, in replacing them I could see why they wore through. The back of drum wheels are just bearings (no balls), the weight of drum had the wheel bearings wear a wide groove in the support shafts so it shifted everything. And front has no bearings it just rides on the seal. I rotated/swapped them all around so they start with a fresh wear face and replaced a wheel. It should support itself better. Maybe we will get 5 more years out of it.
I personally think it's down to cost and planned obsolescence. The bearing is so soft, it's clearly sacrificial. There's a lot of dust from the eroded part, and the spindle was still as new. Even though the part is cheap and fitting it is quick, most people wouldn't know how - and calling someone out to do it would cost more than half the price of a replacement dryer.
Can't be heat - ball bearings, even just steel ones, are fitted to engines and car wheels. A dryer gets hot, but not that hot - and even if it did, ceramics are available. Same with diameter - if it's too small you just increase the spinder size.
Yeah, main bearings on car, like crankshaft and cam are solid bearings and journals. Wheelbearings are a timpkin flat roller, I think, to support a lot of load and thrust. They are packed and sealed. But if it isn't heat, then I would say the part size just gets big when you need an inner race (around shaft), bearings , then outer race, housed in a bracket. Lot cheaper for just the sacrificial part, till the wear like you show starts affecting other parts.