Planned ... obsolensence
August 1, 2011 2:06 AM Subscribe
Numerous front load washers die in a few years due to hidden corrosion of a structural part made of aluminum. Frigidaire, GE, Whirlpool, Kenmore, Electrolux. Examples. Why do they use aluminum when it will be submerged in the presence chemicals and steel?
1) Aluminum actually resists corrosion in exactly the same way that stainless steel does, i.e. instead of corrosion eating away at the metal like a cancer the way it does normal iron, the oxidized metal forms a tough barrier on the surface of the metal which prevents further corrosion. So using steel wouldn't necessarily help there.
2) Steel is a lot heavier than aluminum, and the pieces you're looking at aren't small, so weight may be a factor in their choice of material. That seems to be the main drum you're looking at, which is the main moving part in the machine, so replacing steel with aluminum would not only enable them to use a smaller motor but would significantly reduce power consumption.
posted by valkyryn at 3:21 AM on August 1, 2011
2) Steel is a lot heavier than aluminum, and the pieces you're looking at aren't small, so weight may be a factor in their choice of material. That seems to be the main drum you're looking at, which is the main moving part in the machine, so replacing steel with aluminum would not only enable them to use a smaller motor but would significantly reduce power consumption.
posted by valkyryn at 3:21 AM on August 1, 2011
Best answer: Just bad design. It's easy to argue 'planned obsolescence', but a manufacturer doesn't really design a major appliance to fall apart after a couple of years. Brand loyalty is an important factor, and if your appliances gain a reputation for early failure, you'll lose business. The fact that appliances don't just keep rolling on forever is largely a consequence of what consumers are willing to pay.
posted by le morte de bea arthur at 3:32 AM on August 1, 2011 [3 favorites]
posted by le morte de bea arthur at 3:32 AM on August 1, 2011 [3 favorites]
Best answer: Aluminum actually resists corrosion in exactly the same way that stainless steel does...
Actually, no. If aluminum is in contact with steel, particularly in the presence of water and chemicals, galvanic corrosion is a likely result. It doesn't stop at the surface the way normal oxidation of aluminum does.
This is a bad design. Probably why these washers typically have a one-year warranty.
posted by Kirth Gerson at 3:43 AM on August 1, 2011
Actually, no. If aluminum is in contact with steel, particularly in the presence of water and chemicals, galvanic corrosion is a likely result. It doesn't stop at the surface the way normal oxidation of aluminum does.
This is a bad design. Probably why these washers typically have a one-year warranty.
posted by Kirth Gerson at 3:43 AM on August 1, 2011
1- The first picture in the link shows a steel part.
2- Planned obsolescence is not really the reason. Nobody is saying "lets make sure these things will only last three years". More likely, they design the things for whatever their design lifetime is, which is more like 10 or 15 years, and just screwed up.
3- The design of those "spiders" is just awful. My suspicion is that the corrosion is not the cause of the failures, just a side-issue or perhaps accelerated the failure by a few months. There is just no way a more or less flat piece of metal is going to withstand the kind of stress an unbalanced drum full of water and clothes would put on it.
4- Also, many appliance brands use the same manufacturer(s) to produce their products. It isn't necessarily a "Kenmore is always LG" sort of thing, because they switch off. But if you go to the showrooms, you can see that the same product is sold under different names.
posted by gjc at 4:40 AM on August 1, 2011
2- Planned obsolescence is not really the reason. Nobody is saying "lets make sure these things will only last three years". More likely, they design the things for whatever their design lifetime is, which is more like 10 or 15 years, and just screwed up.
3- The design of those "spiders" is just awful. My suspicion is that the corrosion is not the cause of the failures, just a side-issue or perhaps accelerated the failure by a few months. There is just no way a more or less flat piece of metal is going to withstand the kind of stress an unbalanced drum full of water and clothes would put on it.
4- Also, many appliance brands use the same manufacturer(s) to produce their products. It isn't necessarily a "Kenmore is always LG" sort of thing, because they switch off. But if you go to the showrooms, you can see that the same product is sold under different names.
posted by gjc at 4:40 AM on August 1, 2011
coffeefilter: "Numerous front load washers die in a few years due to hidden corrosion of a structural part made of aluminum."
Do you have anything to back up this statement other than a couple random pictures of dishwasher parts of indeterminate age and origin?
posted by mkultra at 5:15 AM on August 1, 2011 [1 favorite]
Do you have anything to back up this statement other than a couple random pictures of dishwasher parts of indeterminate age and origin?
posted by mkultra at 5:15 AM on August 1, 2011 [1 favorite]
Following on from gjc it is probably the fatigue life of the part that is critical here. The cyclic loading and unloading under varying amounts of washing , both frequency and load size , is the indeterminate failure mechanisn. Fatigue failure has never been a strong point of most designs and this would look like a prime case. It is a major failure mode for car jacks as well although no one thinks it. A compromise for better fatigue life would probably add material , reducing the drum volume and raising the cost so there is little that can be done to maintain price/performance.
The mass hanging off the shaft with the uneven loading is ideal fatigue failure mode and is how the original tests were done on railway wheel shafts over a hundred years ago. An upright top loader features less of this direct cyclic loading. Using fatigue life prediction software on finite element models in the early 90's looked like magic to most engineers and i doubt many more use it now.
posted by stuartmm at 5:30 AM on August 1, 2011
The mass hanging off the shaft with the uneven loading is ideal fatigue failure mode and is how the original tests were done on railway wheel shafts over a hundred years ago. An upright top loader features less of this direct cyclic loading. Using fatigue life prediction software on finite element models in the early 90's looked like magic to most engineers and i doubt many more use it now.
posted by stuartmm at 5:30 AM on August 1, 2011
The first picture in the link shows a steel part.
How do you reach that conclusion? The text for that photo says "The drum is stainless steel and the spider is aluminum," and includes a discussion of galvanic corrosion.
My suspicion is that the corrosion is not the cause of the failures, just a side-issue or perhaps accelerated the failure by a few months.
Those photos all show severe corrosion.
posted by Kirth Gerson at 6:21 AM on August 1, 2011
How do you reach that conclusion? The text for that photo says "The drum is stainless steel and the spider is aluminum," and includes a discussion of galvanic corrosion.
My suspicion is that the corrosion is not the cause of the failures, just a side-issue or perhaps accelerated the failure by a few months.
Those photos all show severe corrosion.
posted by Kirth Gerson at 6:21 AM on August 1, 2011
The protective oxide coating of aluminum dissolves away at pH values below 4 and above 9.
There is a bit of a fad right now for the use of washing soda, and washing soda can produce a pH of 11.
My guess would be that the people who owned these washers were using washing soda.
posted by jamjam at 5:59 PM on August 1, 2011
There is a bit of a fad right now for the use of washing soda, and washing soda can produce a pH of 11.
My guess would be that the people who owned these washers were using washing soda.
posted by jamjam at 5:59 PM on August 1, 2011
The first picture in the link shows a steel part.
How do you reach that conclusion? The text for that photo says "The drum is stainless steel and the spider is aluminum," and includes a discussion of galvanic corrosion.
My suspicion is that the corrosion is not the cause of the failures, just a side-issue or perhaps accelerated the failure by a few months.
Those photos all show severe corrosion.
posted by Kirth Gerson at 6:21 AM on August 1 [+] [!]
1- Because it is stamped, which is not how aluminum parts like that are made. And because it is rusty.
2- They HAVE corrosion, but my contention is that it wasn't the cause of the failure. They failed because they were being loaded with too much stress, developed stress cracks and the corrosion got into the cracks after they began. The corrosion may well have accelerated the failure, but those parts were going to fail regardless. Is what my contention is.
posted by gjc at 6:43 PM on August 1, 2011
How do you reach that conclusion? The text for that photo says "The drum is stainless steel and the spider is aluminum," and includes a discussion of galvanic corrosion.
My suspicion is that the corrosion is not the cause of the failures, just a side-issue or perhaps accelerated the failure by a few months.
Those photos all show severe corrosion.
posted by Kirth Gerson at 6:21 AM on August 1 [+] [!]
1- Because it is stamped, which is not how aluminum parts like that are made. And because it is rusty.
2- They HAVE corrosion, but my contention is that it wasn't the cause of the failure. They failed because they were being loaded with too much stress, developed stress cracks and the corrosion got into the cracks after they began. The corrosion may well have accelerated the failure, but those parts were going to fail regardless. Is what my contention is.
posted by gjc at 6:43 PM on August 1, 2011
1- Because it is stamped, which is not how aluminum parts like that are made. And because it is rusty.
It looks like a casting to me. The "rust" color is probably an artifact of the picture-taking, or of some remnant of an anodized finish.
They HAVE corrosion, but my contention is that it wasn't the cause of the failure. They failed because they were being loaded with too much stress...
Too much stress for a corroded part, sure. I don't thing we're arguing about that, really.
I do wonder why you insist that the guy who was there, and took the picture, and (presumably) replaced the part is wrong about it being aluminum. Here is the complete text accompanying that photo:
It looks like a casting to me. The "rust" color is probably an artifact of the picture-taking, or of some remnant of an anodized finish.
They HAVE corrosion, but my contention is that it wasn't the cause of the failure. They failed because they were being loaded with too much stress...
Too much stress for a corroded part, sure. I don't thing we're arguing about that, really.
I do wonder why you insist that the guy who was there, and took the picture, and (presumably) replaced the part is wrong about it being aluminum. Here is the complete text accompanying that photo:
The drum support spider in this Frigidaire washer had corroded so much that the hub and drive shaft actually broke off. Note the pitting in the metal. That's from galvanic corrosion. It weakened the spider structural strength so much that it failed during use.posted by Kirth Gerson at 5:07 AM on August 2, 2011
Whence cometh galvanic corrosion? Most likely because of dissimilar metals between the spider assembly and the drum setting up a galvanic reaction. The drum is stainless steel and the spider is aluminum. In the wet environment, the aluminum acts as a sacrificial anode, like the zinc rod in a water heater. Some combinations of detergents, fabric softeners, and water quality conditions may set up or exacerbate this galavanic condition inside the washer.
Response by poster: afterword: communication with the mfr leads one to infer that it was a design oversight, that it went on for some years, and newer ones should be steel against steel.
If you have one, you can email the mfr the date of manufacture, model, serial number, and they should be able to tell you what's inside.
posted by coffeefilter at 5:46 PM on August 22, 2011
If you have one, you can email the mfr the date of manufacture, model, serial number, and they should be able to tell you what's inside.
posted by coffeefilter at 5:46 PM on August 22, 2011
This thread is closed to new comments.
posted by rodgerd at 3:04 AM on August 1, 2011 [4 favorites]