OK, the item in question is a dishwasher, supposedly under extended warranty, but this is a perfectly general engineering question that can be related to motor cars, which is why I haven't gone to IHAQ. Please don't let this turn into a dishwasher discussion...
My dishwasher has sprung a leak. Having sat, quiety and undisturbed, in a corner for two years, a leak has mysteriously appeared in the waste pipe, between where it leaves the machine and the trap. The hose looks as though it is made from several two-foot long sections, with some sort of a join between. The leak has appeared within one of these rubber jointing sections - not at the union, but within the joint itself.
So I called the extended warranty number, and was told that leaks in the waste pipe are not covered; all that is covered is mechanical or electrical failure. I was told that the pipe is not covered, as I could have damaged it myself (I didn't). There is no such exclusion in the contract - the chap on the end of the telephone helpfully read out all the exclusions to me (I could read them myself on my copy), including the one regarding lightning strikes or storms or civil disturbance.
Well, I've spent too long as a Material Scientist to agree with them. What constitutes mechanical failure? It quite simply refers to the breaking of something; however that failure may have been caused.
A quick google reveals an extraordinary resource called 'google books'.
Failure of Materials in Mechanical Design: Analysis, Prediction, Prevention by JA Collins
Chapter 2. In the first chapter it was suggested that mechanical failure might be defined as any change in the size, shape, or material properties of a structure, machine, or machine part that renders it incapable of satisfactorily perfoming its intended function.
The author goes on to discuss commonly observed modes of mechanical failure, and both abrasive and impact wear are included.
Is my (science based) understanding of mechanical failure at odds with the understanding of the man on the Clapham omnibus?
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What make of dishwasher is this ?
If it is only the waste pipe that is leaking,it will only cost you a few pounds to replace it and save you the stress of pursuing this further.
If you replace it get a Bosch as they are usually very long lasting and reliable.
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It's a Bosch. (And it had a replacement something or other under warranty two years ago that cost nearly £200 all done.)
No, I disagree about replacement being simple. The waste pipe is plumbed in inside the dishwasher. If I change the waste pipe, then I am a non-authorised person who has taken the cover off and messed about inside it, thus invalidating the extended warranty... Otherwise I would have done.
Hence the discussion about mechanical failure...
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'Is my (science based) understanding of mechanical failure at odds with the understanding of the man on the Clapham omnibus?...'
Yes, I think it's simply that.
Once , when I was a callow & cocky youth, a teacher asked me if Ihad done any 'work' in class.
- I replied, "Of course, Sir" ,
"No, Woodbines, all you've done this class is talk & cause nuisance" said teacher
"But Sir.." , said I (fresh from a previous physics tutorial) "..work is done when energy is used."
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Well it just goes to prove that there is always an exception to the rule.
I have fitted many many dishwashers in my time and can say honestly,that we have never had a problem with a Bosch dishwasher, so I am surprised.
If it had been of italian origin then I would understand.
Going back to your original question,I would agree with Bosch in that if the actual pipe is leaking through a fracture,then at some time it has been bent or kinked through incorrect installation.
The material that the pipe is manufactured from does not degrade and once in situ,has a very easy life.
I have removed my own Bosch dishwaser to fit to my new kitchen and although 16 years old is still in almost daily use and the pipework is fine.
Is this an integrated or free standing dishwaser ?
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Interesting point. It's not a scientific definition, but my take on it would be: if the whole of the substance forming the joint has chemically deteriorated and weakened, then that may be considered "ageing" [or some other imprecise terminology so beloved of warranty companies.]
If however, the joint material is still fundamentally as sound as it was when it was formed; then the leak is therefore a mechanical fracture.
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The point MM is making is that the warranty company seems to be implying that 'mechanical failure' is when part of the 'workings' breaks, not a static part like a hose. That is a different type of machanical failure, which is a scientific phrase rather than a loose term used by the public to define a breakdown.
As such, if the bushes on a motor wear causing it to fail, that is mechnical failure from the warranty perspective.
Not that I agree with it....
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How do you know where leak is from if you have not removed cover to look?
If its inside the machine casing and has not been tampered with then my understanding would be mechanicval failure because it is inside the case of the appliance.
B ut you may have shot yourself in the foot if you have identified the cause of the fault and its inside.
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Warranty "Mechanical failure" applies to the three parts inside the machine that never ever fail.
"Wear and Tear" applies to all parts that do fail and are called "consumables".
Not only are extended warranties a ripoff in price, the cover is useless in general.
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You needn't care about the fine print of the warranty: if a part of the machine has failed so soon, its up to the retailer to fix or replace it. SOGA. We had a machine (Zannussi i think) where the steel inner drum rusted after about 4 years. Not good enough we said: Currys agreed, and replaced the machine. The SS inner drum which you fondly imagine is replicated throughout is but tinsel: the outer drum was the bit that rots. If you haven't fiddled with it, its down to the seller to fix. Bosch can repay them later, if its a manucfturing failure.
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SOGA won't help me, as it came from Powerhouse, who are in administrative receivership. I should have to add my name to the list of creditors and see if there's anything left after BDO's fees.
It is not inside the machine. It is the waste hose that comes out of the machine. Around 18 inches from the machine. As I mentioned in my original post. It is not a conventional hose that looks like a long length of concertina (and so is very vulnerable to damage as it is made of rubbish). It is instead made up of three two-foot long lengths of this concertina hose, and there is some sort of a joint between each section - it therefore looks like an earthworm with a saddle. The joint appears to have been plastic welded to the hose at each end, and the failure is in the middle of the joint. The joint has several corners. As any fule kno, cracks propogate from corners - although I cannot understand why this has been under stress.
Here is an illustration. The concertina bit is represented by the ^^^, the joint by the dashes and underscores, which neatly show the ups and downs in the joint.
^^^^^^^^^^^^^^^--__--__--^^^^^^^^^^^^^^
And here is where the failure is - 'x' marks the spot.
^^^^^^^^^^^^^^^--__--__x--^^^^^^^^^^^^^^
Anyway, back to my original question. What the dickens does mechanical failure mean, then?
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I see now, so SOGA no use for this. Pity. Another line of thought: metal fractures due to many failure possibilities: stress concentrations etc, as you say. Pipelines fail due to say, innappropriate materials or fabrication or design, and they could suffer what is described as mechanical failure, e.g, section of pipe incorporating bellows at Flixborough. Different scale, but plastic pipe you describe has arguably had a mechanical failure, possibly due to manufacturing defect.
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I would think that 'mechanical failure' means it's broken and won't work. Your machine still works so it hasn't failed.
Some suggestions:
1) Call the warranty company again and insist it has failed - stress that the machine will have to be opened up to replace the part.
2) Cut the joint open and repair it with some suitable pipe and a couple of Jubilee clips.
3) Get someone in to do and send the warranty company the bill (the bill should state 'muchanical failure'!). If they won't pay it then issue a claim using MoneyClaimonline.
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I should have to add my name to the list of creditors and see if there's anything left after BDO's fees.
Really hope that was TIC - this is not in any way a pop at that firm in particular, but if there's a surplus after sorting the bank out, a liquidator will be put in to, ahem, deal with it. I'd be pretty surprised if that didn't happen.
The joint has several corners. As any fule kno, cracks propogate from corners - although I cannot understand why this has been under stress.
Only thing I (a non-scientist) can think is that something in the plastic has not enjoyed regular contact with warm/hot water mixed with dishwasher tablet residue and a manufacturing flaw on the inner part of the joint has been progressively weakened by it. That would suggest a manufacturing defect - is such a thing covered?
Anyway, back to my original question. What the dickens does mechanical failure mean, then?
In this context, it will have whatever meaning the warranty company chooses to place on it that will allow them to avoid paying your claim.
Facetiousness aside, I can't really help with the sort of definition you're after, but I can offer the following suggestions which you will probably have already considered anyway:
1) Duck-tape the joint to within an inch of its life and see if this seals it and stops further irrigation of the floor
2) Ring the monkey at the call centre again, explain what you said about having to take the back off the thing to replace the part and ask if, on the basis that they are refusing to entertain a claim for this, you therefore have their permission to repair it yourself, and can you have that in writing, please, with the letter actually being SIGNED by a person and not just having "Customer Services" printed at the bottom.
3) Get in touch with Bosch and see if they have any helpful suggestions about this, i.e. is this part known to be prone to failure etc.
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In this context mechanical failure replies to the method and type of failure not to the type of part concerned
Thus to pick a motoring example an alternator might fail electrically (blown diode etc) or mechanically (siezed bearing etc) but either may be caused by a mechanical agent.
With a waste pipe the chances are that the fracture is caused by vibration, especially as it is at the joint between the reinforcement and the (more) flexible length of hose itself. Fatigue fractures of this type are hard to identify and in this case will be more to do with the specific installation than any manufaturing defect.
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My initial reaction is that "mechanical" implies a moving part or parts. However that does seem a little restricted. How does the dictionary define "mechanical"? Don't laugh, if this went to court the dictionary is the first place the judge would look!
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I started in the dictionary - Concise Oxford (1995)
Mechanical: 'of or relating to machines or mechanisms'.
Machine: 'an apparatus using or applying mechanical power, having several parts each with a definite function and together performing certain kinds of work'.
Failure: 'breaking down or ceasing to function'.
Unfortunately, this dictionary does not include a definition of the phrase 'mechanical failure' which has a very precise (or indeed very broad) meaning to an engineer.
Currently, btw, a combination of araldite, bicycle patches and duck tape seem to be holding body and soul together.
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If the waste pipe is leaking / fractured outside the machine then just cut it and the join it together with whatever is easier for you.A piece of external pipe of the correct diameter and some silicone will do the job.Then wrap insulation tape,tightly wound along the join and a couple of inches either side.This will sort it.
Then you can maybe stop worrying about such trivia and move on with the more important things in life !
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Sorry...this will go to IHAQ if you can't get it off dishwashers and onto motoring by sometime tomorrow.
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PG,
I think it's a fair discussion bearing in mind the wording of many extended warranties for cars.
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